This PDF file contains the front matter associated with SPIE Proceedings Volume 8424, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Excitation energy transfer (EET) in molecular systems is studied theoretically. Chromophore complexes are considered which are formed by a butanediamine dendrimer with four pheophorbide-a molecules. To achieve a description with an atomic resolution and to account for the effect of an ethanol solvent a mixed quantum classical methodology is utilized. Details of the EET and spectra of transient anisotropy showing signatures of EET are presented. A particular control of intermolecular EET is achieved by surface plasmons of nearby placed metal nanoparticles (MNP). To attain a quantum description of the molecule-MNP system a microscopic theory is introduced. As a particular application surface plasmon affected absorption spectra of molecular complexes placed in the proximity of a spherical MNP are discussed.

We rst report on design, fabrication and characterizations of thermally-controlled plasmonic routers relying on the interference of a plasmonic and a photonic mode supported by wide enough dielectric loaded waveguides. We show that, by owing a current through the gold lm on which the dielectric waveguides are deposited, the length of the beating created by the interference of the two modes can be controlled accurately. By operating such a plasmonic dual-mode interferometer switch, symmetric extinction ratio of 7dB are obtained at the output ports of a 2x2 router. Next, we demonstrate ber-to-ber characterizations of stand-alone dielectric loaded surface plasmon waveguide (DLSPPW) devices by using grating couplers. The couplers are comprised of dielectric loaded gratings with carefully chosen periods and duty-cycles close to 0.5. We show that insertion loss below 10dB per coupler can be achieved with optimized gratings. This coupling scheme is used to operate Bit-Error-Rate (BER) measurements for the transmission of a 10Gbits/s signal along a stand-alone straight DLSPPW. We show in particular that these waveguides introduce a rather small BER power penalty (below 1dB) demonstrating the suitability of this plasmonic waveguiding platform for high-bit rate transmission.

We demonstrate the surface plasmon grating coupled emission (SPGCE) from excited organic layer on metal grating in organic/metal structure. The emissions correspond to the resonant condition of SPPs modes on the Alq₃/Au interface and grating couple to the Au/air interface for the emission of light. In our experiments, we used different pitch sizes to control plasmonics band-gap which produced highly directional SPGCE with enhanced intensity. In our experiments, four different pitches, including 400 nm, 500 nm, 600 nm and 800 nm, were adopted for the one-dimensional lamellar grating devices. They were grating devices with 1-D pattern an exposure area of 1.2×1.2 mm² fabricated by Electron-Beam Lithography system. The experimeantal and theoretical results showed that SPGCE at different pitch can match a linear shifting of momentum (ΔK) of about 4.8 μm^-1 per 100 nm pitch size with 4 times enhanced intensity. We have to modify our experimental design of decreasing Au thin film thickness, it became more pronounced in the 20 nm Au film at the pitch of 600 nm structure. In this study, the emission filtering is enabled by evanescent wave coupling across the upper layer metal film. In this way, we can probe the response of the SPGCE system when the two modes are brought into resonance. In our experiments, we used different pitch sizes to control plasmonic band-gap which produced highly directional SPGCE with enhanced intensity. Based on our calculation, SPGCE showed a color change from yellowish green to orange at a certain viewing angle, while the concentration of contacting glucose was increased from 10 to 40%, corresponding to the refractive index change from 1.3484 to 1.3968. This indicated a potential application of low-cost, integrated, and disposable refractive-index sensor. It is proposed for the development of novel bio-devices, which is expected to improve the capability of electroluminescent bio-plasmonic devices in the future.

We present measurement and simulation results of local surface plasmon resonances on silver nanoantenna structures, fabricated with electron beam lithography. Such structures offer interesting possibilities to study strong coupling phenomena between surface plasmon polaritons (SPP) and, e.g., quantum dots, along the lines of our previous work on vacuum Rabi splitting for SPP and dye molecules.

We present a semiconductor quantum optics formalism to study the dynamics of a coherently-driven semiconductor quantum dot interacting with an acoustic phonon bath and a high Q microcavity. A quantum master equation is derived in the polaron frame, where multiphoton and multiphoton effects are included to all orders. As applications of the theory, we study the Mollow triplet of a driven quantum dot in the regime of semiconductor cavity-QED. Pronounced signatures of electron-phonon-photon scattering are observed through excitation-induced dephasing and off-resonant cavity coupling. We also present an effective phonon master in Lindblad form and show example quantum trajectory simulations that help one to understand the features in the Mollow triplet spectra.

Small optical microresonators are structures which confine light to volumes with dimensions on the order of one wavelength and provide an important means for controlling light-matter interaction in integrated optics. In this Paper, we would like to present our work on the study of the interaction of single quantum emitters or nanoparticles located in the confined optical field of a single-mode microresonator. The interaction possibilities between a general photonic system and a quantum system are discussed, with special focus on the effect of resonant microcavities. For the case of the optical microresonator used in our experiments, we present a model based on the transfer matrix method which can analytically describe the radiative enhancement of even complex resonator geometries. This allows not only the optimization of resonator geometries, but gives accurate information on the radiative processes occurring in the cavity, allowing the extraction of information normally inaccessible in optical measurements.

Silicon nitride (SiNx) is an important material for on-chip waveguides and resonators due to its tunable refractive index and low optical loss at the visible and near-infrared wavelengths. In this work, we report our results on second-harmonic generation from SiNx thin films at the fundamental wavelength of 1064 nm. The SiNx thin films with the thicknesses between 100 nm and 1500 nm were prepared on fused silica substrates by plasma enhanced chemical vapor deposition. Strong SHG signal was observed from SiNx films, with the absolute levels significantly higher than those from typical dielectric surfaces. The second-order properties of the samples were fully characterized by second-harmonic generation as a function of the state of polarization of the fundamental field. The polarization dependent SHG indicates that the SiNx films possess in-plane isotropy and polar order along the surface normal. The strong second-order nonlinear response from the SiNx films has great potential applications in the on-chip nanophotonic devices.

We investigate the quantum optical properties of an excited single photon emitter (quantum dot) near the surface of a finite-size metal nanoparticle using a photon Green function technique that rigorously quantizes the electromagnetic fields. We obtain Purcell factors of up to 5×10⁴ due to higher order plasmon modes for both a 7-nm and 20-nm radius metal nanoparticle, and show the failure of employing a dipole approximation in regimes where useful quantum optical interactions occur. We also calculate enormous photonic Lamb shifts of up to 40 meV giving a normalized frequency shift up to |Δω|_max/ω_d = 1.28×10^-2. Considering a small quantum-dot, positioned 2-nm from the metal nanoparticle surface, we demonstrate that the strong coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature and despite the non-propagating nature of the higher order modes. The vacuum Rabi doublet becomes a rich spectral quartet with two of the four peaks anticrossing, and surviving in spite of significant non-radiative decays. We also discuss the role of optical quenching and highlight the importance of accounting for photon transport from the dot to the detector. Our formalism is quite general and can easily be extended to include interactions between multiple quantum dots and multiple metal nanoparticles.

The rigorous analytical approach for the calculation of the spontaneous decay rate for an emitter located in a cylindrical cavity of arbitrary diameter and length is developed. The approach is based on the dyadic Green's function of the Helmholtz equation which is obtained by introducing the fictitious surface current sheets at both ends of the nanocavity. The Hertz vector potentials which describe the electromagnetic field in the system are found as Fourier integrals over the path in the complex plane of the propagation constant. The integral equation which determines the field Fourier transforms is derived. The Green's function is then used to calculate the field susceptibility and the spontaneous decay rate of an emitter located inside a nanocavity. The general theory is illustrated by the calculations for the system which models an InAs quantum dot embedded in a GaAs nanowire.

A theoretical approach, allowing analyzing the role of multipole modes in the extinction and scattering spectra of arbitrary shaped nanoparticles, is developed in the framework of the discrete dipole approximation. The proposed method can be used to control separately the positions of different multipole resonances as a function of nanoparticle sizes, shapes and irradiation conditions. The main attention is given to the first multipole modes including magnetic dipole and electric quadrupole moments. The magnetic quadrupole and electric octupole modes can also be involved in the consideration. The method is applied to nonspherical Si nanoparticles with multipole responses in the visible optical range, allowing a decomposition of single extinction (scattering) peaks into their constituting multipole contributions. The unique property of Si nanoparticles to support magnetic optical response opens new ways for the construction of novel nanooptical elements and can be particularly important for solving the problem of metamaterials with magnetic properties in the visible spectral range.

We present the design, implementation and characterization of an integrated surface plasmon resonance biosensor chip involving diffractive optical coupling elements avoiding the need of prism coupling. The integrated sensor chip uses the angular interrogation principle and includes two diffraction gratings and the SPR sensing zone. The theoretical design is presented as well as the fabrication procedure. Experimental results, using reference index fluids, are compared to theoretical predictions and prism coupling experimental results. We believe that this architecture is perfectly suitable for low cost and reproducible SPR biochemical sensor chips since the sensing zone can be functionalized as any other one.

A novel emerging technique for the label-free analysis of nanoparticles and biomolecules in liquid fluids using optical micro cavity resonance of whispering-gallery-type modes is being developed.A scheme based on polymer microspheres fixed by adhesive on the evanescence wave coupling element has been used. We demonstrated that the only spectral shift can't be used for identification of biological agents by developed approach. So neural network classifier for biological agents and micro/nano particles classification has been developed. The developed technique is the following. While tuning the laser wavelength images were recorded as avi-file. All sequences were broken into single frames and the location of the resonance was allocated in each frame. The image was filtered for noise reduction and integrated over two coordinates for evaluation of integrated energy of a measured signal. As input data normalized resonance shift of whispering-gallery modes and the relative efficiency of whispering-gallery modes excitation were used. Other parameters such as polarization of excited light, "center of gravity" of a resonance spectra etc. are also tested as input data for probabilistic neural network. After network designing and training we estimated the accuracy of classification. The classification of antibiotics such as penicillin and cephasolin have been performed with the accuracy of not less 97 %. Developed techniques can be used for lab-on-chip sensor based diagnostic tools as for identification of different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells and for dynamics of a delivery of medicines to bodies.

Surface plasmon resonance (SPR) biosensors have become a central tool for the study of biomolecular interactions, chemical detection, and immunoassays in various fields. SPR biosensors offer unparalleled advantages such as label-free and real-time analysis with very high sensitivity. To further push the limits of SPR capabilities, novel SPR structures and approaches are being actively investigated. Here we experimentally demonstrate a graphene-based SPR biosensor. By incorporating a graphene layer to the conventional gold thin film SPR structure, its biosensing sensitivity is significantly increased. This is shown in a typical affinity biosensing experiment to measure the real-time binding kinetics of biotin-streptavidin. In addition to higher sensitivity, we also obtain a much higher signal-to-noise ratio without the slightest modification of the usual measurement setup. This implies that a considerably lower limit of detection can be made possible with the novel structure. Moreover, our graphene-based SPR biosensors do not require sophisticated surface functionalization schemes as in conventional SPR in order to function. Previous reports have also suggested that graphene might effectively prevent non-specific binding of biomolecules on the sensor surface. With relatively simple fabrication methods and large scalability, these combined distinctive advantages can enable future generation of high-performance SPR biosensors.

Here, we demonstrate the total extinction of the reflectivity for a transverse magnetic polarized wave on a gold surface etched on a tiny portion of its area by both narrow and deep grooves. At the resonance, the incident energy is funneled towards the grooves aperture and is then dissipated on the grooves sidewalls. Thanks to the decomposition of the electromagnetic field into its propagative and evanescent parts, we unambiguously show that the funneling is not due to plasmonic waves flowing toward the grooves, but rather to the magnetoelectric interference of the incident wave with the evanescent field. This evanescent field is mainly due to the resonant wave escaping from the groove. These high aspect ratio metallic grooves were fabricated using a mold cast technique based on an electrolytic growth of gold. They exhibit a nearly total absorption due to a Fabry-Perot like resonance inside the grooves. We also evidence the incidence-invariance of their spectral response, which undoubtedly shows the localized nature of the resonances. These experimental results confirm the prediction of total funneling of light in very narrow grooves.

Noble metal nanoparticles exhibit tunable optical properties due to surface-plasmon resonances, which depend on the distribution, size and shape of the metallic nanoparticles. In order to handle the nanoparticles they have to be embedded e. g. into a polymer matrix. Here, the synthesis of silver nanoparticles within the polymer matrix is performed by thermal as well as photochemical decomposition of a silver precursor. This in situ synthesis offers the possibility to perform the particle formation before, during or after drying of the soluble polymer matrix. In detail, we focus on the particle generation after processing blends of the polymer and the silver precursor as thin films. A very broad range of mass fractions of nanoparticulate silver from 0.001 up to 0.3 was realized, which allows the adjustment of the surface-plasmon resonance. For low silver nanoparticle contents up to 1 wt.% the surface-plasmon resonance peak is typically observed in the blue spectral region, whereas higher silver amounts cause a high extinction in the visible and near infrared spectral range. As polymeric matrix poly(vinylidene fluoride-trifluoroethylene) was chosen und prepared in a thin-film geometry. On the long range the prepared nanocomposites represent multifunctional materials due to the expected ferroelectric properties of the polymer and the surface-plasmon resonance properties of the silver nanoparticles. In addition to the optical properties, the influence of the particle synthesis on the polymer matrix and morphology is studied. As a result, any degradation of the polymer is excluded.

In this work we report the use of the localized surface plasmon resonance dumping to achieve the detection of different organic molecules in liquid and in vapor phase. The all-optical sensor has been obtained by the development of noble metal nanoparticle/polymer nanocomposites. An interesting property of these nanocomposites is that their polymeric matrix is based on a photosensitive compound which allows ultra-violet (UV) lithography and hence they can be patterned with a resolution determined by the host. Positive and negative tone nanocomposites, containing silver or gold nanoparticles (NPs), have been developed. This fabrication technique is a fast, simple and non-expensive approach to the formation of extended polymer patterns with embedded silver nanoparticles. Moreover, the material constitutes a mechanism to position nanoscale particles in the range 5-40 nm with resolution limited by the UV lithography, which represents a useful tool for nanoscience. By using this nanostructured plasmonic material, the detection of amines and 2- mercaptoethanol molecules has been achieved, both in dilution in water and in vapor phase. The sensing mechanism is based on the plasmon signal dumping related to the binding of the organic molecules at the surface of the nanoparticles, which produces a color change that can be appreciated with the naked eye. This nanocomposite constitutes a platform for the fabrication of colorimetric arrays of bio/chemical sensors.

Scanning second harmonic generation (SHG) microscopy is becoming an important tool for characterizing nanopatterned metal surfaces and mapping plasmonic local field enhancements. Here we study G-shaped and mirror-G-shaped gold nanostructures and test the robustness of the experimental results versus the direction of scanning, the numerical aperture of the objective, the magnification, and the size of the laser spot on the sample. We find that none of these parameters has a significant influence on the experimental results.

A multilayered waveguide, which supports surface plasmon polaritons, is considered as an absorption modulator. The waveguide core consists of a silicon nitride layer and ultrathin layer with the varied carrier density embedded between two silver plates, which also serve as electrodes. Under applying voltage to electrodes the carrier density in the transparent conducting oxide layer (we study indium tin oxide - ITO) changes according to the Thomas-Fermi screening theory. We employ analytical solutions for a multilayered system as well as numerical simulations with the commercial software package CST Microwave Studio in the frequency domain. We explore different permittivities of the ITO layer, which can be achieved by utilizing different anneal conditions. To increase transmittance and enhance modulation depth or efficiency, we propose to pattern the continuous active layer. Dependence from the pattern size and filling factor of the active material are analyzed for tuned permittivity of the ITO layer. Direct simulation of the device functionality validates optimization design.

We present the experimental study of a new design of band-pass filter based on guided-mode resonances in a free-standing metal-dielectric structure with subwavelength gratings. Component consists of a subwavelength gold grating with narrow slits deposited on a silicon nitride membrane. High optical transmission is measured with up to 78% transmission at resonance. Experimental angularly resolved spectra are presented: they reveal the role of the diffracted orders and of the waveguide eigenmode in the resonance. Spectra have a typical profile of Fano resonances: we show that this profile is due to interferences between a direct transmission channel through the 0th order, and an indirect transmission channel which results from the excitation by the ±1 diffracted orders of a waveguide eigenmode.

We studied the near-field optical properties of colloidal gold nanocubes (GNCs) using a photochemical imaging method. This method is based on the vectorial molecular displacements, of photosensitive azo-dyes, which are sensitive to the polarization of the optical near-field of the GNCs. We analyzed the spatial confinement of both electromagnetic hot and "cold" spots with a spatial resolution up to 15nm (λ/35). The new concept of cold spot presents valuable and complementary electromagnetic information to the well known electromagnetic hot spot. We demonstrated that cold spots are highly sensitive to polarization and can be much more confined than hot spots enabling them to be applied in high resolution imaging and spectroscopy.

In 2011, a survey conducted all over the world says that more than 7 million humans around the world died of cancer. One in three women and one in two men developed cancer during their lifetime. About 15 percent of all deaths worldwide, was attributed to cancer. In some nations, cancer will surpass heart disease to become the most common cause of death. This thesis attempts to conquer this immortal illness. Here, we present a radical platform of cancer treatment based on silver nanoparticle-developed ''conglomerate'' photothermal vapour nanobubbles. These conglomerate plasmonic nanobubbles are capable of diagnosing (by optical scattering technique) and therapeutic action (by mechanical, nonthermal and selective annihilation of target cells) of cancerous cells without affecting adjoining normal cells. At first, theoretical simulation of optical fiber SPR sensors was carried out. Then these nanosensors were designed, fabricated and their sensitivities were measured experimentally. We introduce the nanosensors and describe how their sizes, environments, sensitivities, specificities, efficacies and selectivities can be harnessed to detect and treat cancerous cells. This paper has been written from the quest to launch something that can eradicate this disease from our bodies and societies forever.

Hybrid systems coupling gold nanoparticles to fluorophores have been realized, aiming to investigate the conditions to get two-photon fluorescence (TPF) enhancement effects through nanoantenna or Purcell effects. The use of gold nanorods (NR) was chosen : due to their anisotropic form they indeed exhibit two localized surface plasmon resonance (SPR) modes: one in the visible (associated to the transverse size of the NR) and another in the infrared (associated to the NR longitudinal size), one key point being the possibility to adjust these two resonances to the optical properties of the two-photon fluorophores to be further coupled to the NRs (emission λ_em and excitation λ_exc wavelengths). Detailed investigation of the intrinsic NR TPF signal dependence was first considered. Experiments were performed in aqueous solutions using a Ti-Sapphire laser source emitting 100 fs pulses in the 750-950 nm wavelength range. We observe that the maximum TPF signal is located at the NR surface plasmon resonance wavelength, pointing the role of field enhancement effects in the observation of the increased NR TPF. As a next step, the nanoparticles were immobilized onto previously treated indium tin oxide (ITO) coated glass substrates and a method to couple fluorescent molecules (a polyphenylene vinylene (PPV) derivative) to the previously immobilized NRs was then studied: the so-called layer-by-layer technique was more particularly investigated in order to control the realization of hybrid systems coupling the fluorescent PPV polymer and particles at varying distances. In order to perform joint optical and topographic characterizations, a stand-alone atomic force microscopy (AFM) platform was integrated to our TPF microscopy set-up. The influence of the number of spacing layers on the TPF of such hybrid systems was studied. First results seem to indicate the existence of a specific distance allowing TPF enhancement. A more detailed study considering the intensity and lifetime of such hybrid system is currently under way in order to fully quantify the signal enhancement origin.

We present here an alternative approach to local nanoscale light sources for excitation of surface plasmons based on second-harmonic generation (SHG) in inorganic crystalline nanowires. It is shown that the nanowires can serve as tunable coherent local source for surface plasmon polariton (SPP) excitation. Inorganic crystalline nanowires made of potassium niobate (KNbO₃) have previously been shown to have a large second-order optical non-linearity, which allows for efficient second-harmonic- and sum-frequency generation. It has also been demonstrated that the fields generated by scattering off nanfibers deposited on an air/metal interface can couple to SPP modes at the interface and thereby excite SPPs at the interface. We have combined SHG in nanowires with SPP excitation through scattering off nanowires deposited on thin silver and gold surfaces. To detect second-harmonic radiation that has been efficiently coupled into SPP modes at the air/metal interface, angular resolved leakage radiation spectroscopy was performed for pump wavelengths between 800 and 1300 nm.

This paper outlines the experimental methods and results obtained from the testing of asymmetric gold surface plasmon waveguide detectors on an epitaxial silicon structure at optical wavelengths of 1550 nm and 1310 nm. Using end-fire coupling, responsivities of up to 0.88 mA/W at a 100 mV reverse bias were measured. The photo-detection mechanism is based on the internal photoelectric effect. The simple and compact design allow for these devices to be integrated and densely populated with Si-based optoelectronics. The ability to detect wavelengths below the bandgap of Si is also appealing. 2D responsivity maps are generated using piezoelectric positioners controlled using Labview.

Surface plasmon polariton (SPP) excitation at a gold-vacuum interface via 800 nm light pulses mediated by a periodic array of gold ridges is probed at high lateral resolution by means of photoemission electron microscopy (PEEM). We directly monitor and quantify the coupling properties as a function of the number of grating ridges and compare the PEEM results with analytic calculations. An increase in the coupling efficiency of ≈ 3 is observed when increasing the number of ridges from 1 to 6. We observe, however, that a further addition of ridges is rather ineffective. This saturation behavior is assigned to the grazing incidence excitation geometry intrinsic to a conventional PEEM scheme and the limited propagation distance of the SPP modes at the gold-vacuum interface at the used wavelength.

We present a thorough numerical investigation of end-fire coupling between dielectric-loaded surface plasmon polariton (DLSPP) and compact rib/wire silicon-on-insulator (SOI) waveguides. Simulations are based on the three-dimensional vector finite element method. The interface geometrical parameters leading to optimum performance, i.e., maximum coupling efficiency or, equivalently, minimum insertion loss (IL), are identified. We show that coupling efficiencies as high as 85 % are possible. In addition, we quantify the fabrication tolerances about the optimum parameter values. In the same context, we assess the effect of a metallic stripe gap and that of a horizontal offset between waveguides on insertion loss. Finally, we demonstrate that by benefiting form the low-loss coupling between the two waveguides, hybrid silicon-plasmonic 2 x 2 thermo-optic switching elements can outperform their all-plasmonic counterparts in terms of IL. Specifically, we examine two hybrid SOI-DLSPP switching elements, namely, a Mach-Zehnder Interferometer (MZI) and a Multi-Mode-Interference (MMI) switch. In particular, in the MZI case the IL improvement compared to the all-plasmonic counterpart is 4.5 dB. Moreover, the proposed hybrid components maintain the high extinction ratio, small footprint, and efficient tuning traits of plasmonic technology.

The possibility to use the tip of a scanning tunneling microscope (STM) for the realization of a highly localized molecular light source is discussed. Since it is not limited by photodegradation or quenching effects, Second Harmonic Generation (SHG) appears as a valuable alternative to luminescence. In the case of dipolar approximation however, the existence of a noncentrosymmetry is mandatory to get a non-vanishing signal. We show that the static electric field present inside a scanning tunneling microscope (STM) junction can be used towards creating a very local noncentrosymmetry via molecular orientation under the tip. An experimental set-up was specifically designed consisting in the integration of a STM head to an inverted optical microscope, coupled to a femtosecond Ti-Saph laser excitation. The operation of this system has enabled to get the first images with a SHG contrast of a sample structured at the micron scale. The objective is now to improve resolution. To this respect, electromagnetic field engineering appears as a key point. One way consists in exploiting optical nano-antenna effects. In a first approach, the possibility to benefit from local electromagnetic field enhancement effects occurring in the presence of metallic nano-wires was studied. Extrapolation of these results shows that imaging with about 50 nm resolution should be within reach, which opens new perspectives in the field of optical local probe microscopy.

We use the nonlinear optical property of GaAs to directly visualize the path of the near infrared incident laser light coupled into individual nanowires. We fully illuminate with near infrared pulse laser untapered and tapered GaAs nanowires grown via the Au-assisted vapor-liquid-solid mechanism. We record second-harmonic generation (SHG) signals in the visible spectrum. In some nanowires, an interference pattern is observed and investigated in terms of distances between the maxima of the SHG signal taking into account the effective refractive index in such sub wavelength structures with radius below 90 nm. We propose a model to explain the periodicity of the maxima in the SHG interference pattern. The theoretical model includes the waveguiding and the Mie scattering theories for obtaining the 2π periodicity fitting well the experiments. Moreover, we also measure interferences in tapererd nanowires with a radius down to 76 nm. The possible effect of the gold in non radiative recombination and the presence of the gold particle at the tip of some nanowires are also discussed.

The synergy between photonics, nanotechnology and biotechnology is spawning the emerging fields of nano-biotechnology and nano-biophotonics. Photonic innovations already hurdle the diffraction barrier for imaging with nanoscopic resolutions. However, scientific hypothesis testing demands tools, not only for observing nanoscopic phenomena, but also for reaching into and manipulating nanoscale constituents in this domain. This report is two-fold desribing the new use of proprietary strongholds we currently are establishing at DTU Fotonik on new means of sculpting of both light and matter for bio-probing at the smallest scales.

Back-focal plane interferometry is typically used to determine displacements of a trapped bead which lead to trapping force measurements in optical tweezers. In most cases, intensity shifts of the back-scattered interference pattern due to displacements of the bead are measured by a position sensitive detector placed in the microscope back-focal plane. However, in intensity-based measurements, the axial displacement resolution is typically worse than the lateral resolution since for axial displacements, the inherent resolution of the position detector cannot be used. In this paper, we demonstrate that measurement of the phase of the back-scattered light yields high axial displacement resolution, and can also be used for lateral displacement measurement. In our experiments, we separate out the back-scattered light from the trapped bead and reflected light from the top surface of the sample chamber by a confocal arrangement consisting of a spatial filter used in combination with two apertures. We proceed to beat the two separated components in a Mach-Zehnder interferometer where we employ balanced detection to improve our fringe contrast, and thus the sensitivity of the phase measurement. For lateral displacement sensing, we match experimental results to within 10% with a theoretical simulation determining the shift of the overall phase contour of the back-scattered light due to a given lateral displacement by using plane wave decomposition in conjunction with Mie scattering theory. Our technique is also able to track the Brownian motion of trapped beads from the phase jitter so that, similar to intensity-based measurements, we can use it to determine the spring constant of the trap, and thus the trapping force. The sensitivity of our technique is limited by path drifts of the external interferometer which we have currently stabilized by locking it to a frequency stabilized diode laser to obtain displacement measurement resolution ~200 pm.

The exact theory of generating the "entangled photons" by excited motionless two level atom in one-dimensional high finesse nanocavity with a single resonance linearly polarized mode, decaying at the rate Γ, is presented. We have investigated the evolution of resonance emission out of the macromolecule-like system "nanocavity with resonance mode and excited atom" in area 0≤ Γ≤ 0.2g , where g is a coupling constant for electro-dipolar interaction. We have revealed that the source of arising of the entangled photons at the outlet of nanocavity is disintegration of metastable interference superpositional field structure, ejected through the partly transparent mirror out of the cavity. This structure is produced by the self-consistent AC Stark effect, created by electrical fields of rotating atomic dipole and resonance mode. The field splits atomic levels and radiation transitions between them, producing in the nanocavity pairs of anti-phase (ω_a ± g)- photons. Since the rate of mode damping Γ << g these photons form in the cavity metastable interference superposional structure consisting of resonance mode carring wave with amplitude modulated with frequency 2g. The profiles of (ω_a ± g )- components have identical form exp(-t Γ)t Γ, with average lifetime in the cavity being estimated as 4ln Γ/Γ.

In this work we show that the insertion of a dielectric layer in Au/Co/Au magnetoplasmonic nanodisks fabricated by hole mask colloidal lithography makes it possible to obtain systems that simultaneously exhibit large magneto-optical (MO) activity and low optical extinction. The physical mechanism underlying this effect is the internal EM field redistribution, in such a way to concentrate it in the MO active layer (Co) and, at the same time, reduce it in the non MO active elements. We have performed a systematic study of the optical and MO response upon the variation of the Co layer thickness within the nanodisk, finding an increase of the MO response with the increment of thickness, accompanied with a blue shift and broadening of the peaks associated with the plasmon excitations.

We investigate the contributions of the propagating and the evanescent waves associated to freely-propagating nonparaxial light beams whose transverse component at some plane is azimuthally polarized. In terms of the plane-wave angular spectrum of these fields, analytical expressions are given for determining both the spatial shape of the above components and their relative weight integrated over the whole transverse plane. The results are applied to a kind of doughnut-like beams with transverse azimuthal polarization.

Structurally coloured natural photonic crystals found in several insects are made of ordered porous chitin structures. In such photonic crystals, colour changes can be induced by relative gas/vapour concentration variations in a mixed atmosphere. For instance, when the composition of the atmosphere changes, the colour of Morpho sulkowskyi buttery is modied. Based on this eect, it is possible to identify closely related gases/vapours. In spite of increasing interests for such sensors, the fundamental mechanisms at the origin of the selective optical response are still not well understood. The point is that refractive index variations resulting from the introduction of a specic gas species in the atmosphere are too small to justify the dramatic changes observed in the optical response. Here, we demonstrate through numerical simulations that indeed gas/vapour-induced refractive index changes are too small to produce a signicant modication of the spectral reectance in a representative 3D periodic model of natural porous nanostructures. For this purpose, we used the rigorous coupled wave analysis (RCWA) method for modelling light scattering from inhomogeneous optical media. The origin of the reported colour changes has therefore to be found in modications of the porous material and their impact on the photonic response.

A new configuration of the one-dimensional reflective asymmetrical metallodielectric grating structure for unidirectional excitation of surface plasmon polaritons (SPPs) is proposed. The structure is embedded between two different dielectric media and composed of two 1D metallic gratings each of the two consisted of periodically placed rectangular metal stripes. The case of normal incidence is analysed. It is shown that even a small horizontal shift between these two layers or a change in dielectric contrast of the grating fillings, the structure may redirect an energy flow of the SPP in the near field. An explanation of this unidirectional SPP excitation is given. Besides the SPP excitation by a plane wave, the excitation by a finite-diameter 3D Gaussian beam is analysed as well, as the beam facilitates visualisation of the SPP finite propagation length and efficiency of the directivity switch. It is shown that the switching phenomenon exists together with a high concentration of the electromagnetic field at the structure, the feature especially desirable in techniques of subwavelength nanovisualisation. The configurations analysed may be also useful in designing optical devices as optical switches, VLSI devices, light harvesting photodetector structures or, in general, in any case where efficient control of energy propagation directivity is of primary importance.

Highly luminescent semiconductor nanocrystals or quantum dots (QDs) possess a number of interesting and important properties that are tunable thanks to their size-dependent discrete electronic spectra. In this work we studied the optical properties of a novel type of hybrid structures that combine CdTe QDs with organic dye molecules (Pseudocyanine iodide) in a J-aggregate state. Due to the excitonic nature of electronic excitations, J-aggregates have the narrowest absorption and luminescence bands among organic materials, large oscillator strengths and giant third-order nonlinear susceptibility. In developed structures optical energy harvested by the quantum dots as artificial antennas then transferred to J-aggregates to enhance the photostability and efficiency of the carriers recombination. To fabricate CdTe/J-aggregates hybrid nanostructures we have used an approach based on electrostatic interaction between the positively charged dye and CdTe QDs capped with thioglycolic acid and, thus, carrying a negative charge. In order to develop an efficient hybrid material operating in the FRET regime, we carefully selected the PL colors (diameters) of the QD to be optically coupled with absorption of J-aggregates. We took advantage of extremely thin ligand shell (~0.5 nm) of CdTe QDs, which insures high efficiency of energy transfer. Formed QD/J-aggregate FRET system shows the broadband absorption in the visible and the ultraviolet part of the spectrum typical of QDs, along with the narrow emission linewidths characteristic of J-band emitters (~15 nm full width at half-maximum). We use absorption and photoluminescence spectroscopy and photoluminescence lifetime studies to conclude that efficiency of energy transfer is 95%. Also we report on development of active whispering-gallery microcavities integrated with with hybrid QDs/J-aggregate shell. Results of micro-PL spectroscopy and PL lifetime imaging confirm strong quenching of QDs emission and multifold shortening of their photoluminescence lifetime, which is consistent with highly efficient FRET in hybrid organic/inorganic semiconductor nanostructures coupled to microcavity modes.

Various silver nanostructures, semi-ball, jungle, and dendritic, are demonstrated by an electrical deposition process. The formation of silver nanostructures with various morphologies is studied by the mechanism of the diffusion limited aggregation (DLA) model. A array pattern of silver nanostructures can be obtained when the conductive substrate was used in a uniform electrical filed. A thickness 500 nm of Alq3 thin-film was covered on the silver nanostructure by thermal evaporation method. The strongest intensity of Alq3 green emission was observed when the pattern-array dendritic silver nanostructure was covered by Alq3. It can be explained with the plasmonic coupling due to the Alq3 and dendritic nanostructure. The result can help us to further application the patterned-array silver dendritic nanostructure for advanced opto-electronic device.

Metallic wire-grid polarizers (WGP) transmit TM-polarized light (transverse magnetic) and reflect TE polarization (transverse electric) efficiently. They are compact, planar and compatible with integrated circuit (IC) fabrication, which simplifies their use as optical components in nanophotonic, fiber optic, display, and detector devices. In this work, Al bi-layer WGPs were designed and numerically simulated using finite element methods. Optical properties of the polarizers were analyzed in the deep-ultraviolet (DUV) to infrared (IR) regions. It was observed that Al bi-layer WGPs show broadband and high TM transmission and extinction ratio. A comparison of the performances of single and bi-layer WGPs show that the latter is highly advantageous over the former one. An extensive study of the dependence of the optical properties of single and bi-layer WGPs on structural parameters, such as period, metal thickness, and, duty cycle (DC), is provided. Optimal structural parameters are obtained within the feasible parameters in terms of nanofabrication. An Al bi-layer polarizer with a period of 80 nm and a metal layer thickness of 40 nm showed transmission up to 80% and extinction of 40 dB (10⁴) and broadband polarizing behavior down to a wavelength of 250 nm.

Nanometer-size colloidal semiconductor nanocrystals, or Quantum Dots (NQD), are very prospective active centers because their light emission is highly efficient and temperature-independent. Nanocomposites based on the incorporation of QDs inside a polymer matrix are very promising materials for application in future photonic devices because they combine the properties of QDs with the technological feasibility of polymers. In the present work some basic applications of these new materials have been studied. Firstly, the fabrication of planar and linear waveguides based on the incorporation of CdS, CdSe and CdTe in PMMA and SU-8 are demonstrated. As a result, photoluminescence (PL) of the QDs are coupled to a waveguide mode, being it able to obtain multicolor waveguiding. Secondly, nanocomposite films have been evaluated as photon energy down-shifting converters to improve the efficiency of solar cells.

We study decoupled and coupled types of surface plasmons in the near UV wavelength range (λ = 193, 365, 405nm) in circular metal film diaphragms composed of concentric sub wavelength nanoslit grooves.

We synthesized a mixture composed of gold nanoparticles of various shapes using the wet chemistry method. The final solution contained long nanorods, balls, disks and different spherical nanoparticles. To separate particles of individual shapes from the reaction mixture, the solution was centrifuged in a glucose density gradient. A distribution of nanoparticles based on their diameters was observed and each section was collected independently and each type of nanoobjects was characterised separately. Finally, the difference in nanoparticle shapes depending on the presence of Ag⁺ ions in the growth solution is reported and its influence on the separation is discussed.

Second-harmonic generation upon femto-second laser irradiation of nonlinearly optically active nanofibers grown from nonsymmetrically functionalized para-quarterphenylene (CNHP4) molecules is investigated. Following growth on mica templates, the nanofibers have been transferred onto lithography-defined regular arrays of gold square nanostructures. These nanostructure arrays induce local field enhancement, which significantly lowers the threshold for second harmonic generation in the nanofibers.

A theoretical scheme for laser cooling in Tm³⁺-doped oxy-fluoride glass ceramic (GC) is presented. It is shown that the unique combination of high chemical and mechanical stability of the oxide glass and low phonon energy of the fluoride nano-crystals, which trap a majority of Tm³⁺ ions, is beneficial for laser cooling of solids. The effective embedding of rare-earth ions in the crystalline phase with low phonon energy provides high quantum efficiency for the ³F₄ → ³H₆ transition involved in the cooling cycle in the Tm³⁺ ions, which is a key parameter for laser cooling of solids.

We study the electromagnetic behavior of a structure consisting of coupled aluminum nanodisks on a silicon waveguide at telecom wavelengths. Numerical simulations show that the fundamental TE-like waveguide mode excites a localized magnetic plasmon resonance between adjacent nanodisks with suitable dimensions, leading to transmission dips. For a sufficient number of disks (periodically distributed along the propagation direction), the structure supports a magnetic mode arising from a magneto-inductive coupling between neighboring nanodisks, as revealed by an Eigenmode analysis. The transmission response of the samples was measured for both polarizations through an end-fire set-up, confirming that the strong resonances are only present for TE polarization. Measurements and simulations are in good agreement, showing that the resonances strength is maximized for three coupled nanodisks.

In 2010, the existence of a zero of transmission at high wavelengths different from the Rayleigh Wood anomaly was highlighted when two identical subwavelength gratings are brought close enough. We recently revealed the origin of this transmission extinction and the mechanism is recalled here. Furthermore, we present an experimental setup to measure the amplitude of this extinction and study its spectral behavior when changing geometrical parameters which represent a real technological challenge. This way a new generation of tunable filters in the mid-infrared with perfect spectral shape control and high rejection efficiency can be designed with practical use to gas sensing applications.

We fabricated horizontal slot waveguides using two low temperature deposition techniques ensuring the full compatibility of the processes with CMOS technology. Slots width as thin as 45 nm with smooth slot surfaces can easily be fabricated with simple photolithographic steps. Fundamental TM-like slot mode in which the E-field is greatly enhanced within slot showed a 23.9 dB/cm and a 18 dB/cm in a PECVD SiC/SiO₂/SiC and a ALD TiO₂/Al2O₃/TiO₂ vertical slot waveguide, respectively.

In this study, we synthesized different types of ZnO samples (thin and nanostructured films) and investigated their potential application in biomedicine. The properties of ZnO films are strongly dependent on the synthesis process and the experimental conditions. Thus, the samples were prepared by pulsed laser deposition (PLD), which allows excellent control over the stoichiometry and surface morphology. Cell suspensions of the same concentration and volume (i.e. same number of cells) were seeded on each sample. The subjects of interest were 3T3 fibroblast, MCF-7 and HeLa cancer cells. The influence of the ZnO surface morphology on the viability of these three different cell cultures was studied. The cell type defines the appropriate surface morphology for cell culturing. The nanoscale morphology of the samples supports the HeLa cell viability, while only a small quantity of MCF-7 cells are able to adhere, spread and survive on them.

We study photoinduced molecular reorientation of the azobenzene derivative Disperse Red 1 embedded in poly(4-vinylpyridine) polymer matrix. Photoinduced axial order leading to birefringence and polar order leading to second-order nonlinear optical (NLO) response are induced by purely optical means. These two photoinduced properties are found to exhibit markedly different dependences on the chromophore concentration: the photoinduced second-order NLO response reaches its peak already at 23 wt. % concentration while the photoinduced birefringence increases up to 51 wt. % concentration. The results show that chromophore-chromophore intermolecular interactions work against polar order already at modest concentration. The axial order, on the other hand, is not as easily affected by such interactions.

This work presents a solvent-free and laser-assisted growth of gold nanoparticles (Au-NPs) within silica monoliths using both Au(III) and Au(I) precursors. The novelty of the synthesis method is that Au-NPs of about 20 nm in diameter were obtained well dispersed in the matrix with no need of either reducing or capping agents. Moreover, the laser-assisted synthetic procedure here described made it possible to obtain reproducible 2D and 3D patterns of Au-NPs. For this purpose, suitable Au(I) and Au(III) precursors, soluble in dichloromethane, were easily prepared following a well-known procedure. The mesoporous silica matrix was first loaded with the precursors via a simple impregnation and then irradiated using either a continuous laser (λ= 266 or 532 nm) or a pulsed laser (λ=800 nm; pulse: 120 fs; repetition rate: 1KHz). In all cases, a photothermal gold reduction was observed. The Au-NPs have been characterized using UV-vis absorption spectroscopy, x-ray diffraction and Transmission Electron Microscopy. Finally it is shown that the excess gold precursors can be removed after the Au-NP synthesis by a simple washing of the monolith with a few immersions in the pure solvent. The stability of the Au-NPs was further tested by a series of heat-treatments up to 500°C, showing that the silica monolith acts as an effective support to prevent the agglomeration of the nanoparticles.

Blue emitting CdSe/ZnS quantum dots (QDs) were encapsulated with the ligand 11-(N-carbazolyl) undecanoic acid (C11). Steady-state photoluminescence (PL) experiments show an enhancement of the QD emission upon the excitation of the carbazole ligand in solution compared to the situation where a solution with the same concentration of QDs capped with oleic acid (OA) were excited at the same wavelength. This suggests energy transfer from the carbazole moiety to the QD cores. When incorporating the QDs in a poly (N-vinylcarbazole) (PVK) matrix, a significant enhancement of the QD emission upon the excitation of PVK was also observed indicating an efficient energy transfer from PVK to the QDs in the case of C11 capped ligands. Confocal microscopy images of the doped PVK films show clearly better miscibility of PVK and QDs capped with C11 compared with those capped with OA. Nanosecond time-resolved PL experiment shows evidence of singlet transfer with Förster resonance energy transfer (FRET) efficiency of 39% for the QDs in solution, while the efficiency of this process amounted to 15.6% for a PVK film doped with 30 wt% of the QDs. The smaller efficiency of the singlet transfer compared to the overall efficiency of energy transfer, suggested by the stationary PL spectra suggests an important role for triplet energy transfer. Electroluminescent devices were prepared with the structure; ITO/PEDOT:PSS/doped PVK with C11 capped QDs/Butyl PBD/Aluminum. Upon applying voltage, the devices show pure blue electroluminescence at low concentration of QDs (10 wt%) with a turn on voltage close to 6V.

The optical properties of two-dimensional (2D) photonic crystal (PhC) slabs based on self-assembled monolayer of dielectric microspheres are studied. The in-plane transmission spectra of 2D array of dielectric spheres with triangular lattice are investigated using the finite-difference-time-domain (FDTD) method. The structures studied are monolayer of dielectric spheres infiltrated with air ('opals') and air spheres infiltrated with dielectric material ('inverse opals'), with glass substrate sustaining the monolayer of spheres. The transmission spectra are calculated for different values of refractive index contrasts between the spheres and the infiltrated material and for different values of filling fractions (compactness of the spheres). As the refractive index is varied, compact spheres are assumed; and as the filling fraction is varied, the refractive index of the dielectric spheres or the dielectric matrix is fixed to be 2.5. For compact opal structure on glass substrate, a narrow photonic band gap (PBG) is observed in the transmission spectra for dielectric spheres with refractive index higher than around 1.9. When the refractive index is fixed at 2.5, the PBG is observed for more compact spherical arrangement and disappears for more separated spheres. While for inverse opal structure on glass substrate, using non-compact spheres enlarges the width of PBG which is not observed for compact spherical arrangement. The application of the study is to realize organic PhC microcavity laser.

In this paper, a novel T-shaped plasmonic metal-insulator-metal (MIM) splitter with one input and two outputs is proposed, which uses simple stacked Bragg reflectors placed on both the left and right branches. Simulation results show that the resonance wavelengths of the surface plasmon polaritons (SPPs) can be effectively controlled and guided along the desired direction with high confinement by properly designing the parameters of the structure, such as the refractive index of the dielectric, the period and the number of dielectric modulations N. Moreover, the splitting ratio is found to be adjustable by tuning the value of N.

This paper is intended to demonstrate the effect of surface plasmon coupled emission (SPGCE) on the plasmonic response of lamellar grating in both Au-grating/Alq₃ and PR-grating/Alq₃ nanostructures. Recently, intriguing studies on an appropriate nanostructure of the corrugation allows the non-radiative SPP mode to be coupled out as light into the far field with direction determined by the grating diffraction condition. It has also been shown that surface plasmon coupled emissions (SPCE) from fluorescent molecules by incident wave excite an evanescent field near the periodic metallic structure, Kretschmann configuration and multilayer grating structure to increase the radiation efficiency. In this paper, we propose to use this technique of SPGCE has performed on the localized surface plasmon (LSP) and surface plasmon band gap (SPBG) characteristics of the lamellar grating nanostructure.

We investigate the femtosecond pulse propagation in medium with nanorods under the conditions of both changing the ellipticity (aspect ratio) of nanorods and dependence of TPA from aspect ratio of nanoparticles. The relation between the width of nanorods absorption spectrum and width of laser pulse spectrum as well as detuning of central frequency of absorption spectrum from carrier frequency of wave packet is taken into account at analyzing the laser pulse propagation. This detuning leads to appearance of phase grating which can essentially influence on the laser pulse propagation and compensate the action of pure amplitude grating caused by nonlinear absorption. We found that under certain conditions the distortion of laser pulse spectrum is really absent despite action of various nonlinearities. The second very important effect consists in substantial shift of maximal intensity in time domain due to spectrum self-modulation because of induced pure amplitude grating. This leads to light slowing-down. It should be emphasized that this effect is similar to spatial motion of maximal laser intensity at infrared optical radiation propagation in clouds.

Photoluminescence enhancement of CdSe/CdS/ZnS QDs by localized surface plasmon resonance of large Au-NPs has been investigated. The photoluminescence of the QDs with an emission wavelength at 620 nm in a PMMA matrix is enhanced by immobilized Au-NPs. By considering the lifetime and excitation dependent photoluminescence we realized that the emission and excitation rate enhancements both contributed to the total photoluminescence enhancement. PL measurements were carried out for different sizes of Au-NPs to find out their influences on the emission of QDs. The largest enhancement is achieved by applying 80 nm Au-NPs. Silanization method gives us the opportunity easily to prepare samples with different concentrations of Au-NPs. It is revealed that increasing the concentration of the Au-NPs layer provides higher scattering cross section which contributes in PL enhancement.

Semiconductor quantum dots (QDs) exhibit unique optical properties like size-tunable emission color, narrow emission peak, and high luminescence efficiency. QDs are therefore investigated towards their application in light-emitting devices (QLEDs), solar cells, and for bio-imaging purposes. In most cases QDs made from cadmium compounds like CdS, CdSe or CdTe are studied because of their facile and reliable synthesis. However, due to the toxicity of Cd compounds and the corresponding regulation (e.g. RoHS directive in Europe) these materials are not feasible for customer applications. Indium phosphide is considered to be the most promising alternative because of the similar band gap (InP 1.35 eV, CdSe 1.73 eV). InP QDs do not yet reach the quality of CdSe QDs, especially in terms of photoluminescence quantum yield and peak width. Typically, QDs are coated with another semiconductor material of wider band gap, often ZnS, to passivate surface defects and thus improve luminescence efficiency. Concerning CdSe QDs, multishell coatings like CdSe/CdS/ZnS or CdSe/ZnSe/ZnS have been shown to be advantageous due to the improved compatibility of lattice constants. Here we present a method to improve the luminescence efficiency of InP QDs by coating a ZnSe/ZnS multishell instead of a ZnS single shell. ZnSe exhibits an intermediate lattice constant of 5.67 Å between those of InP (5.87 Å) and ZnS (5.41 Å) and thus acts as a wetting layer. As a result, InP/ZnSe/ZnS is introduced as a new core-shell quantum dot material which shows improved photoluminescence quantum yield (up to 75 %) compared to the conventional InP/ZnS system.

Coupling surface plasmon resonance mode to waveguide mode(s) by simply forming a dielectric layer on top of the metallic layer can improve the sensor's response to molecular variations. In this study, optimization of Coupled Plasmon - Waveguide Resonance (CPWR) sensors' layers to enhance their sensitivities is investigated. Optimizations of wavelength and thicknesses for highest sensitivities of the angularly interrogated CPWR sensors are accomplished with Fresnel equations and the full width half maximum calculations. Sensitivities are determined for three different film layer configurations that consist of: (I) gold-alumina, (II) silver-alumina, and (III) gold-silver-alumina layers. Optimum thicknesses and wavelength combinations for highest sensitivities are calculated in four steps in the spectral and the physical domains. The sensitivities averaged for the biolayer refractive index varying in the range of 1.330-1.385 are mapped around the optimum point of thickness combination as function of metallic and dielectric layer thicknesses at optimum wavelength. Results from our parametric study show that there is approximately 60-fold improvement in the sensitivity for optimized sensor design by comparing with a typical plasmonic sensor. The highest sensor's sensitivity is obtained at λ = 600 nm with the gold-silver-alumina layer combination. This study develops a detailed understanding of how both the dimensional and the spectral parameters affect the sensitivity of the CPWR sensors.

The role played by surface plasmon in metal NPs-dye interaction is discussed. Importance of the optical spacer is addressed based on time resolved photoluminescence experiments. The potential application of metal NPs surface plasmon to organic light emitting diodes is highlighted.

Gold nano-cavity arrays supported on polydimethylsiloxane (PDMS) have been created using colloidal lithography. PDMS is cured on top of hexagonally close packed arrays of polystyrene spheres of diameter 820 nm resulting in a close packed sphere imprinted polymer block. The depth of the imprints is 200 nm, indicating the whole sphere is not entrapped in the polymer during curing. The spherical nature of the imprint can be deformed by stretching of the flexible polymer, thus creating cuboid shaped arrays. Finally, the arrays are coated with a 100 nm gold layer, which conforms to the polymer surface to create either spherical or cuboid shaped gold nano-cavities. Experiments show that the reflectance properties of the arrays are critically dependent on the shape of the cavity. Spherical shaped cavity arrays display diffuse reflectance peaks at wavelengths slightly shorter than the diameter of the templating sphere, which are absent in the cuboid arrays. Both spherical and cuboid arrays show reflectance which is strongly dependent on the angle of incidence, with the cuboid arrays showing differing spectra depending on the direction of the impinging light with relation to the axis of stretching. The changes in optical behavior between the spherical and cuboid cavity arrays is discussed with relation to the change of shape of the patterning feature at the interface.