MOEMS and Miniaturized Systems XXIV

Attoseconds: When intense light interacts with a gas of atoms (or a transparent solid), electron wave packets are released. Attosecond pulse formation exploits the correlated electrons and holes, forcing the electron to return. Without the plasma connection, two of the most important strong-field process that accompany attosecond pulse formation—hot electron formation (inverse Bremsstrahlung) and non-sequential double ionization (collisional ionization)—seemed mysterious. These plasma-like processes lead to laser induced electron diffraction and orbital tomography. THz generation: Terahertz pulse formation by ionization has a similar linage. Using PIC codes to describe azimuthally polarized l=4 mm and 2 mm light interacting with a 150 µm thick jet of helium, we calculate THz pulses reaching 8.5 Tesla. But 10 Tesla is not a limit. 30 THz azimuthally polarized beams can be amplified in high-pressure CO2 reaching isolated magnetic fields of 1-gigagauss.

In recent years, topological phenomena in photonic systems have attracted much attention, with their striking features arising from robust states in the energy gaps of spatially periodic media. However, light waves are entities that extend in space as well as time, such that one may ask whether topological effects can also occur in the temporal domain, or even space-time. Intuitively, systems that are periodic in time may be gapped in momentum, leading to topological states localized at time interfaces. However, time - in contrast to space - exhibits a unique unidirectionality often referred to as the “arrow of time”. Inspired by these features, I will present our most recent experiments on topological states residing at temporal interfaces. Moreover, I will discuss the formation of spacetime-topological events and demonstrate unique features such as their limited collapse under disorder and causality-suppressed coupling.

Quantum technologies promise a change of paradigm for many fields of application, for example in communication systems, in high-performance computing and simulation of quantum systems, as well as in sensor technology. However, the experimental realization of suitable system still poses considerable challenges. Current efforts in photonic quantum science target the implementation of practical devices and scalable systems, where the realization of quantum devices and controlled quantum network structures is key for envisioned future technologies. Here we present our progress on the engineering of integrated photonic systems, which can overcome current limitations for the realization of scalable photonic systems. Specifically, our research currently focuses on three different but complementary topics: integrated devices based on lithium niobate circuits, engineering and harnessing the temporal-spectral structure of quantum states of light, and photonic quantum computation.

We report on the development of a new 2D MEMS spatial light modulator for high-speed (250kHz) amplitude and phase modulation from UV to NIR. The Planar Light Valve (PLV) is a 32 x 256 pixel array with individually programmable 7-bit amplitude or phase control. The PLV is targeted at laser applications requiring high switching speed, high power handling and analog amplitude or phase control. We describe the primary technical challenges in realizing the PLV including: (a) materials selection & development, (b) MEMS process design, (c) MEMS electro-mechanics and (d) CMOS driver design. We present preliminary test results including stroke, linearity, efficiency, contrast, switching speed and cross-talk.

We present a MOEMS integrated photonic pressure sensor with an overall sensor footprint smaller than 500 x 500 µm2. We discuss (i) the design to allow recording pressures from millibars to several bar with 10 µm thick membranes; (ii) the fabrication process relying on substrate removal of a Photonic Integrated Circuit realized using multi-project wafer services and subsequent bonding to a fused silica interposer with laser-processed alignment marks and cavities onto which the membrane is suspended; (iii) the opto-mechanical characterization showing signal integrity and a more than 1 nm Bragg wavelength shift achieved for pressures up to 1 bar.

2x2 optical gates control power and phase in programmable silicon photonic circuits. However, state-of-the-art optical gates are power-hungry due to using heaters and large due to using Mach-Zehnder Interferometers. We demonstrate a compact, low-power 2x2 optical gate using a silicon photonic MEMS dual-drive directional coupler. The device includes a 50 μm long coupling section, two MEMS comb-drive actuators with nW static power consumption and was implemented on a silicon photonics foundry.

III/V semiconductors exhibit high carrier mobility, facilitating high-frequency operations. By combining the photodiode based on these semiconductors with silicon nitride (Si3N4) waveguide, a groundbreaking platform for photonic integrated circuits can be fabricated. This integration allows the superior electronic properties of III/V materials with the robust waveguide, enabling high frequency operation. In this paper, we present a detailed procedure for the integration of III-V optoelectronics with Si3N4 waveguides using the micro-transfer printing.

Depth-based eye tracking eliminates the need for multiple LEDs to triangulate cornea position, simplifying the ET system and improvising robustness. Time-of-flight (ToF) technology further enhances design by negating the need for baseline distance between illumination and detection, enabling compact, single-package designs. This paper presents a MEMS micromirror-based indirect ToF (iTOF) system using 5GHz RF modulation. The micromirror, sized 1.5mm x 1.5mm with a 600µm optical aperture, resonates at 17kHz and 31kHz, achieving fast Lissajous imaging over a 60x60 degree FOV. The iTOF system operates at 10fps, 0.2mm depth accuracy, and 100x100 resolution, enabling eye-tracking and other sensing applications.

Miniaturization of optical devices is crucial for modern technology, especially in VR/AR. Conventional optics face limitations when scaled down, but metasurfaces offer a solution. We demonstrate a near-eye VR display using metalenses, achieving wide field-of-view and compact form and 3D floating display using metalens arrays. Moreover, metalenses operate from UV to IR, enabling applications in photolithography and night vision. Metasurfaces allow precise light control, advancing holographic displays and LiDAR. In 3D imaging, metasurfaces enable 180° field-of-view projection. To overcome commercialization barriers, we introduce nanoparticle-embedded-resin (PER) for manufacturing metasurfaces. PER properties are tailored by varying nanoparticles. We develop TiO2 PER (visible), Si PER (IR), and ZrO2 PER (UV). We also propose a hybrid material for nanoimprint lithography. For patterning, we use ArF photolithography with wafer-scale nanoimprint lithography for scalable manufacturing. These advances promise to accelerate optical device miniaturization for real-world use.

Avian eyes have evolved a deep central fovea, enabling efficient refraction of light for magnified imaging and motion tracking. This adaptation is crucial for detecting and tracking objects in dynamic environments. Additionally, avian eyes can perceive a broad spectrum of light, including visible and ultraviolet wavelengths, aiding in differentiating target objects from complex backgrounds. Despite advancements in artificial vision systems inspired by animal vision, the exceptional object detection and targeting capabilities of avian eyes, utilizing foveated and multi-spectral imaging, remain underexplored. In this study, we present an artificial vision system leveraging these unique features of avian vision. Our system incorporates an artificial fovea and vertically-stacked perovskite photodetector arrays, optimized through simulations to demonstrate foveated and multi-spectral imaging. Our system successfully identifies colored and mixed-color objects and detects remote objects through foveated imaging. Furthermore, we discuss its potential applications in unmanned aerial vehicles requiring detection, tracking, and recognition of distant targets in dynamic environments.

A free-space propagation based optimization method is used to optically compute and design polychromatic diffractive optical elements (DOE) and meta-lenses using a phase spatial light modulator (SLM) in the visible range, subsequently demonstrating their encoding onto photoresist on glass using grayscale lithography. The iterative computational optimization procedure starts with a Gerchberg-Saxton computed initial phase for creating broad features on the SLM with switched RGB lasers. The near or far field hologram pattern is captured by a detector and the phase pattern is further optimized to refine the sharp features of the target intensity profile, adjusting for the chromatic phase responses of the SLM and the photoresist material. We experimentally encode the optimized phase profile onto a multilevel surface relief DOE with 7 bit grayscale lithography. The fabrication process is shown to be compatible with nano-imprint lithography for high volume manufacturing.

Self-written waveguides (SWWs) are well investigated and established to create low-loss connections between different optical components, i.e. waveguides, fibers, light sources or detectors by local photo-polymerization using near-UV light. We will present our recent investigation of this process used to fabricate customized micro-lenses on fiber tips without any required fiber alignment step which reduces the process time, i.e. compared to direct laser writing processes, significantly. We show results regarding the characterization of different materials and viscosities correlating with their contact angle and the optical behaviour compared to a corresponding simulation.

This work presents AlScN driven quasi-static MEMS scanners for the stabilization of a laser mode inside of an ion trap cavity. Quasi-statically, the MEMS scanners FoV surpasses 20° TOSA at ±105 V in x- and y-direction and 16° TOSA during spiral scanning. Driven in resonance, a scan angle of 100° TOSA at 550 Hz in a single axis and 50° in spiral scanning are measured. Additionally, the reflecting plane moves by more than 100 μm at ±5 V in z-direction in the resonant piston mode. This 3D movement can stabilize an optical resonator in an ion trap to promote the Purcell effect which drastically increases the read-out efficiency of the trapped ions quantum state. This addresses a significant scalability challenge in trapped ion quantum computing for systems exceeding 100 Qubits. Therefore, miniaturization and customization of the MEMS-scanners for further integration into the ion trap cavity are ongoing.

This talk will cover the proposed MEMS mirror-based SPAD LiDAR System, a key component enabling real-time safety monitoring in smart factories where workers and equipment collaborate. The designed LiDAR system includes 905 nm pulsed laser beam, double-convex lens based related optics, piezoelectric biaxial MEMS mirror, and SPAD detector featuring large region of interest and enhanced detection performance. The achieved field of illumination (FOI) of the developed system is 80°×60° and corresponding evaluation results including real-time human and object measurement will be provided.

We report a miniaturised structured light engine based on a single-axis MEMS torsion mirror illuminated by a visible laser diode with a collimator and Powell lens in the beam path. The system can illuminate a square-based-pyramidal field subtending angles of up to 30 degrees in both X and Y, and fringe patterns suitable for 3D image capture can be generated by applying appropriate modulation to the laser. The MEMS mirror is designed for a resonant frequency of 25 kHz and, using bespoke FPGA-based drive electronics, we can generate arbitrary sequences of binary fringe patterns, each with up to 652 fringes, at a rate of up to 50,000 frames per second. Alternatively, grey-scale fringes can be generated at lower frame rates using pulse-width modulation at pixel level. The system is expected to find applications in 3D image capture requiring high frame rate, for example production line inspection systems.

Monocrystalline silicon-based quasi-static 2D-MEMS vector scanners are classified as micro-opto-electro-mechanical systems (MOEMS). These controllable micromirrors are primarily utilized for the high dynamic and precise deflection of laser beams in applications such as light detection and ranging (LiDAR), optical coherence tomography (OCT), and compact therapeutic laser systems. While system integration can be difficult, the use of hybrid-integrated electromagnetic (EM) drives—including moving magnet types—yields higher energy densities and require lower driving voltages than those seen in conventional monolithically integrated electrostatic drives, thus facilitating innovative design options for MOEMS. However, this work presents an approach for the physical modeling and control of a quasi-static 2D-MEMS vector scanner with a gimbal-suspended, hybrid-integrated moving magnet drive. A general procedure for the static and dynamic characterization of the system is provided. Furthermore, the performance of the proposed control system is evaluated using a set of non-resonant vectorial scan trajectories.

Spectral analysis of light is at the heart of countless scientific discoveries, techniques and instruments. Miniaturized spectrometers have recently seen great advances, but combining low complexity with high performance remains challenging. We report a novel integrated photonic spectrometer that is based on imaging of light propagation patterns in multi-mode interference waveguides. Both broadband analysis of continuous spectra and classification of distinct wavelengths with suitable machine learning techniques is demonstrated. A spectral resolution of 0.05 nm and resolving power of 16,000 are demonstrated in the near-infrared range, along with integration of four spectrometers in a single chip-array and permanent attachment of optical input fiber for stable operation. Device performance is optimized by selective roughening of the MMI waveguide surface by plasma etching, resulting in high-fidelity operation down to picowatt levels. Canonical applications include astronomical instrumentation and seamless integration with optofluidic lab-on-chip sensors.

Portable Raman systems are highly promising due to their label-free detection, rapid analysis, and onsite capabilities. However, miniaturizing a spectrometer while maintaining high performance is challenging. This work reports a grism microspectrometer with high spectral resolution. The grism structure consists of two transmission gratings coupled with a prism, separated by an air gap. This configuration enhances spectral resolution using two transmission gratings while effectively eliminating stray light caused by the dual gratings through total internal reflection in the air gap. The grism microspectrometer demonstrates a high spectral resolution of ~1.5 nm and an operational range of 230 nm, covering up to 4000 cm-1 at 638 nm excitation wavelength. The grism microspectrometer will enable label-free, rapid, onsite diagnostics through its implementation into a portable Raman system.

Near-infrared (NIR) spectrometry, particularly in diffuse reflection mode, enables non-destructive measurement of material spectral response without specialized sample preparation. However, specular back reflection from windows introduces unwanted signals, causing non-linear photometric errors, especially in highly absorbing materials. This study models backreflection and proposes compensation by subtracting it from the measured spectrum. Validated with milk, a suitable candidate due to its high water content, the method reduces absorbance error from 0.5 AU to 0.05 AU. This advancement holds promise for precise material analysis in industrial, medical, mining, agriculture, and food applications.

A miniaturized tuneable light source using a white LED and the Fastie-Ebert configuration of a mini-spectrometer is demonstrated. In this setup, the CMOS sensor in this Fastie-Ebert configuration is replaced with a DLP2010 0.2 WVGA Digital Micromirror Device (DMD). Experimentally, 36 wavelengths within the range of 615 nm to 685 nm were tuned by changing the pattern on the DMD and activating 10 columns of mirrors. This resulted in narrow spectral lines with a FWHM between 3.24 nm and 5.85 nm. The demonstrated optical performance, both theoretically and experimentally, showcases a miniaturized broadband tunable light source based on a DMD.

For the large-scale intergration of MEMS micro mirrors Fraunhofer IPMS has realized a novel lever-type actuator facilitating a combined push-pull and tip-tilt operation at mechanical stroke of up to +/-1.5µm (3.0µm total) and +/- 2.0 deg tilt deflection. The design relies on four torsional actuator plates serving as levers, which are hinged to a common center plate forming the base for the mirror on top. Such architectures also have been implemented on active CMOS address circuits providing first devices of highly integrated 512 x 320 micro mirror arrays (MMA). Besides a description of the design architecture and the basic driving concept, we will present first characterization results on the mirrors’ static and dynamic deflection behavior, such as obtainable deflection ranges and surface profiles.

A high-resolution, wide-angle scanning micro-electro-mechanical-system (MEMS) mirror with a vertical-scanning linear actuator is realized. To achieve this characteristic, we overcome the tradeoff between resolution attributed to optical flatness and scanning angle. We found pairs of flexures from static deformation on mirror gives sub-peaks at a focused beam spot by diffraction phenomena and the sub-peaks degrades resolution quality. Our reinforcing ribs feature circular structure to omni-directionally disperse the sub-peaks. This mirror with circular ribs dramatically reduced the intensity of sub-peaks to less than 1/100 of the main-peak. Strehl ratio on reflected light from the mirror, indicating amount of aberration, is above 80% corresponding to diffraction limit, without degradation of driving performance of 40 degrees at 25V. As combined with our horizontal mirror, our laser-beam-scanning system has potential to achieve beyond 85 degrees of diagonal field of view and 2560×1440 pixels of resolution.

Waveguide-based broadband light sources in photonic integrated circuits are useful for applications ranging from device characterization to chemical sensing to absorption spectroscopy. This work demonstrates a waveguide-coupled optical source capable of broadband light emission and waveguide propagation from visible-to-infrared wavelengths. A foundry-processed SiN/SiO2 nanophotonic waveguide has two doped-Si microheater strip lines placed on either side of it. A bulk-micromachining trench undercut etch is performed in which the silicon substrate is isotropically-etched to suspend the Si/SiN/SiO2 structure enabling exceptional thermal isolation. A bias is applied to both doped-Si microheaters resulting in efficient Joule heating, and the resulting hot lattice thermal emission couples to and propagates down the SiN waveguide. Measurements show a broadband spectrum ranging from 875-1715 nm (limited by our instrumentation) consistent with a blackbody emission. This broadband thermal source has the potential for high efficiency via subsequent waveguide optimization.

This paper reports a new electromagnetic scanning mirror for wide-field coaxial LiDAR designs. The scanning mirror consists of an enlarged mirror plate supported by two torsional polymer hinges with high impact resistance. An indirect-driving mechanism was developed to achieve large tilting angle through mechanical amplification without sacrificing the resonance frequency. For demonstration, a prototype scanning mirror was designed, fabricated, and characterized. A Hall scan position sensor was integrated to monitor the pose of the mirror in real time. An experimental coaxial LiDAR setup was also built with the fabricated scanning mirror to evaluate its feasibility and imaging capability.

Optical Physical Unclonable Functions (PUFs) have been investigated as hardware-based encryption sources in the information era. With their inherent unpredictability and high complexity, innovative communication protocols are suggested, from simple authentication to encoded image exchange. To facilitate the development of these security platforms, retaining enormous space of challenge-response pairs (CRPs) (i.e., function input-output) is necessary for higher encoding capability. To expand the CRP space effectively, we construct an optical system employing a 4-λ laser diode, rotatable mirrors, and an adjustable aperture with a unique quartz PUF tag. PUF tag is fabricated through a sophisticated wet etching process, having tons of micro-pits on the surface. When illuminated, pits generate complicated speckle patterns resulting from a superposition of thousands of interferences. Each element consisting of the system can manipulate the incident light independently, resulting in many distinct images. The large CRP space serves as an infrastructure for the next-generation encryption primitives.

We report on an integrable electro-optic modulator (EOM), exploiting the advantages of substrate-free thin-film technology to achieve a small device footprint of less than 30 µm along the beam propagation direction. By integrating an active layer into a resonant Fabry-Pérot structure made of miniaturized, substrate-free thin-film elements, an EOM, which modulates the transmitted amplitude, is manufactured and characterized. We show results on electro-optically active polymers as the Fabry-Pérot cavity material, which have revealed an electro-optic coefficient in the three-digit pm/V range at near infrared wavelengths. Furthermore, we analyze applicability of piezoelectric zinc oxide as the active layer material. We explore enhancement of ZnO piezoelectricity by UV light due to inverse piezophototronic effect. When fabricated using microwave assisted magnetron sputtering under oblique angle deposition conditions, resulting porous inclined ZnO films have the potential to achieve a piezoelectric coefficient of over 100 pC/N.

We introduce an optomechanical vector scanner with integrated focusing functionality. Utilizing piezoelectric actuators, our device is lightweight and compact, weighing under 5 grams with dimensions of less than 40 mm × 40 mm × 6 mm. A compliant mechanism decouples the focusing and scanning functions, achieving non-resonant mechanical tilt angles of ±4 degrees and focal power tuning of ±17 diopters. Operating in reflection with a gold-coated glass surface, our device ensures high optical quality. Additionally, with a minor modification, it can achieve low-order wavefront correction, enhancing its versatility.

In this work we demonstrate the performance of the tunable large optical aperture silicon based Fabry-Perot interferometer (FPI) modules for mid-infrared (MIR) hyperspectral imaging. Large optical aperture and good signal-to-noise ratio of these FPIs brings added value for spectral imaging in the MIR range, thus improving material detection capabilities in areas like chemical imaging, industrial sorting and earth observation for example.

Standard Diffractive Optical Elements (DOEs) fabricated as structured surfaces on the scale of visible light wavelength are typically static and require demanding, burdensome, and irreversible lithographic processes. Here we report a maskless lithographic framework that only uses light to fabricate reprogrammable diffractive optical elements directly on the surface of a photo-morphable azopolymer film. Unlike standard photoresists, azopolymers develop surface reliefs directly in the irradiated area, producing phase-modulating masks immediately after illumination. Reprogrammable diffractive gratings, lenses and holograms are demonstrated to change shape and functionality according to dynamic optical surface remorphing, enabling on-demand operating miniaturized optical devices

Solid-phase synthesis is essential for manufacturing biological materials, including proteins and nucleic acids, and other organic compounds. It drives advancements in drug development, genetic engineering, and personalized medicine. This technique immobilizes reactants on solid supports, enabling stepwise reactions with precise molecular assembly. While advantageous for product isolation and reaction control, solid-phase synthesis faces challenges such as unexposed solid support surfaces and trapped impurities, leading to synthesis errors and high resource usage. Here, we introduce a microfluidic optoelectronic platform for solid-phase synthesis. Our device employs light-orchestrated microdroplet reactors to encapsulate and decapsulate individual solid supports (microbeads) with picoliter-volume reagent microdroplets. By ensuring complete and uniform reagent exposure, our platform significantly reduces synthesis errors and improves yields. We have successfully demonstrated on-chip enzymatic oligonucleotide coupling and are expanding to other reactions. Additionally, our platform cuts reagent consumption and waste by up to a million-fold compared to traditional methods,

Structural color arises from lightwave’s interaction with physical structures. It is gathering popularity rapidly for its durability and convenience. Conventional structural coloring schemes, however, rely heavily on high-index, nanoscale structures that are difficult and costly to realize. We demonstrate a new, multipole-based design which enables facilely tunable structural coloring in microscale meta-pixels made of low-index, soft lithography-compatible polymers, and verify the design with experiments and simulations.

Studies on trce-gas spectroscopy are intensifying considerably in recent years due to the great demand for reliable sensors in the quantification of gas concentrations in various fields, including environmental monitoring, medical sensors, early fire detection and security control. Among various approaches, photoacoustic spectroscopy (PAS) is promising due to wavelength independence, zero background and small investigating volumes. In this context, we report the realization and implementation of two new low-frequency, spring-like Micro Electro Mechanical System (MEMS) acting as microphones in a PAS setup. The MEMS behaviors were studied experimentally both in amplitude and frequency modulation, analyzing the figures of merit (FOM) of each approach. Finally, a comparison is reported in terms of detection performance with respect to the different geometric dimensions of the two MEMS investigated.

We present a novel fabrication process of glass-based micro opto electromechanical systems (MOEMS) for various applications, such as tunable optical filters and lenses, and highly transparent MEMS with integrated diffractive elements, showcasing the potential and advancements in glass- MOEMS technology. Our glass micro systems include optical components, highly flexible spring-structures, integrated actuators, and capacitive or piezo-electric sensing elements. They were fabricated using laser induced deep etching (LIDE) to create high aspect ratio structures (up to 50:1) with precise, defect-free features (<10 ±1 µm) using various glass types e.g., fused silica and borosilicate glass. All additional techniques are commonly used microsystem processes such as wet etching, thin-film deposition, and anodic bonding. Overall, we show that LIDE emerges as a potent solution, enabling scalability and effectively addressing the traditional fabrication challenges and that glass-based MOEMS hold significant promise for advancing microtechnology, providing a versatile platform for the next generation of miniaturized optical systems.

Planar SERS substrates are vital for sensing due to their ease of use, lab-on-chip compatibility, and superior reproducibility compared to metal nanoparticles, but their weak interaction with macromolecules and cells limits their adoption. To address this, we explored the impact of nanopatterned curvatures on SERS performance using a 3D-printed micromechanical bending structure i.e. microbender with a 150 µm long membrane and 30 µm rotating arms. Simulations showed that the nano-pillar height is crucial for enhancing field localization, with curved arrays achieving a 25-134% increase in localized field intensity. Printed arrays of various pillar heights and diameters on the microbender membranes demonstrated improved SERS intensity through Raman microscopy, with the 6 µm tall arrays showing a comparable performance to dense short nanostructures. The adaptable microbender technology can be applied to other optical components, suggesting that curved SERS substrates offer more sensitive and versatile sensing solutions compared to traditional dense nanostructures.

We demonstrate a custom-made light-sheet microscope based on tunable structured illumination (SI) frequencies using a grating light valve (GLV) for in-vivo cardiac organoid imaging. Furthermore, we also introduce three image processing techniques to characterize the beating patterns of sequential beating cardiac organoid images acquired by our custom-made light-sheet microscope.

Miniaturized beam steering mirrors are required in numerous applications like (i) LIDAR, or (ii) miniaturized therapeutic lasers. Recently, Fraunhofer IPMS developed a new type of electrostatic vectorial (2D quasi-static) MEMS scanning mirror. The vectorial MEMS scanner was specially optimized for the requirements of the new highly compact therapeutic medical laser system. This laser application requires a highly miniaturized MEMS scanning system for fast and precise vectorial beam positioning of the treatment laser with a positioning time of ≤ 5 ms. The quasi-static 2D drive of the vectorial MEMS scanner is based on vertical comb actuators in combination with a non-cardanic suspension of the 2.2 mm circular mirror, For high laser powers of > 1.5 W (CW) at 519 nm, highly reflective coatings based on enhanced (hybrid) Al with R ≥ 98 % are used. In this contribution we focus on the experimental investigation and optimization of the positioning dynamics of the vectorial MEMS scanning mirrors to achieve a fast and precise beam steering of the medical treatment laser. Furthermore, we discuss the packaging and system integration of the MEMS scanning mirrors in more detail.

Hyperspectral photodermography offers a promising approach to objective skin assessment. However, traditional instrumentation techniques often rely on fiber-optic components that pose challenges in reducing system size. Here, we present a compact, fiber-free optical module integrating multiple white LEDs and a high-resolution miniaturized spectrometer. The module captures characteristic reflection spectra from multiple source-detector separations for enhanced accuracy and sensitivity. The proposed design facilitates convenient multimodal skin analysis and holds the potential for advanced non-invasive assessment of various skin quality parameters.

This study presents a novel endoscopic device that addresses key limitations in current systems by integrating a fiber-optic piezoelectric MEMS hybrid scanner with a shape memory polymer (SMP) catheter. The MEMS scanner uses aerosol-jetted PZT bimorph push-pull actuators and nonlinear vibration to generate controlled circular and spiral scan patterns, enabling high-resolution imaging and an enhanced field of view (FOV). A tapered optical fiber reduces scattering and facilitates independent 2-axis scanning, improving imaging performance. The newly developed SMP catheter offers exceptional flexibility for navigating complex anatomical structures, with programmable multi-stage movements that enhance maneuverability. Experimental validation demonstrates a 60 μm spiral scan area at a 10 Hz frame rate, successfully reconstructing fine details such as 5 μm lines and Psychodidae wing structures. The catheter provides 360° bending, 540° twisting, and 30% extension. The system's versatility is further highlighted by its integration with micro-display technology using a field-programmable gate array (FPGA), significantly improving diagnostic accuracy and efficiency.

Acousto-optic modulator (AOM) is a key optical component functioning in a wide range of applications such as optical networks, internet of things (IOT) and quantum computing systems. AOMs compared to electro-optic modulators consume less power and have unique functionalities of narrow bandwidth and frequency modulation. Despite the maturity of silicon fabrication processes, silicon lacks the intrinsic photo-elasticity property required for optical modulation. Thin film lithium niobate (TFLN) has high photo-elasticity and piezoelectricity coefficients, enabling integration of AOM within a single material. Here we report on the simulation, fabrication and characterization of the acoustic actuators, as a key unit of an AOM, within a standard thin film LNOI PIC platform, applicable in an integrated gyroscope.

Surface-enhanced Raman scattering (SERS) nanoparticles (NPs) have been demonstrated in multiplexed molecular imaging with promising results. Recently, we have been developing a Raman spectrometer integrated with a MEMS scanner for manipulating 2D excitation laser on a sample. When the samples are incubated with SERS NPs, the proposed system can spatially go through the interest of region, acquire SERS signals, and quantitatively analyze the spectra using demultiplexing algorithm in 2D Raman images

Light Detection and Ranging (LiDAR) systems are essential for autonomous driving and drone robotics due to their high-density, accurate data clouds. The advancement of Micro-Electro-Mechanical Systems (MEMS) technology has significantly improved LiDAR, enhancing size, weight, power efficiency, and cost. This study introduces a novel single crystal silicon (SCS) MEMS mirror, with a 10 mm diameter, driven by electrostatic forces. The MEMS design incorporates thousands of comb drives, providing high electrostatic driving force for rapid, precise mirror movements and a large tilting angle. This results in high resolution, determined by the product of optical scanning angle and aperture diameter. On-chip capacitance sensing ensures robust closed-loop control, enhancing stability and settling time during dynamic operations. Our SCS MEMS mirror is manufactured through foundry using an 8-inch single crystal silicon wafer process, suitable for high-volume, low-cost production. Initial results show a field of view of 4° and a scanning frequency of 40 Hz, with ongoing developments aiming for a field of view over 60° and a resonant frequency above 300 Hz.

The colorimetric sensor, which transduces physical information into visible colors, is an intriguing sensor. The metal-hydrogel-metal (MHM) structure, based on the Fabry-Perot resonance, has been investigated as colorimetric humidity sensor due to its hygroscopic properties. However, conventional MHM shows low responsiveness because the superstrate metal barrier hinders water-hydrogel interaction. Additionally, the subtractive coloration limits color gamut. Here, we propose a nanostructured Fano resonator colorimetric sensor (nFRCS) that offers fast response and an ultra-wide color gamut through additive coloration. The Fano resonant optical coating, which couples the continuum state of a lossy medium with the discrete state of MHM, generates Lorentzian reflection spectrum. Nanohole arrays in nFRCS provide a direct pathway for water to reach the hydrogel layer and produce plasmonic resonances that suppress undesired color reflection. Roll-to-plate nanoimprint lithography is employed to finely transfer nanohole patterning. Consequently, nFRCS shows 141 % of the standard RGB and 105 % of Adobe RGB. In terms of responsiveness, it demonstrates response times in the millisecond range.

This work proposes a miniaturized liquid crystal (LC) based electro-optic (EO) scanner design to deflect for two dimensions. LC is an active material controlled by the electric field, eliminating the need for moving parts. This LC-based EO scanner is divided into two stages. The horizontal stage uses an offset electrode design to deflect the beam horizontally, and the vertical stage uses LC-based diffraction grating to deflect the beam vertically. The maximum horizontal and vertical deflection is 13° and 10.9° respectively. This low-cost and miniaturized can be used in augmented reality (AR), virtual reality (VR), or standalone micro-display applications.