This PDF file contains the front matter associated with SPIE Proceedings Volume 10825, including the Title Page, Copyright information, Table of Contents, Introduction, and Author and Conference Committee lists.

A precision patterning sub-nanometrology in a single quantum state such as a single electron, a single photon, a single atom, a single molecule, etc. leads an international technology roadmap for semiconductors (ITRS) to quantum noise limits, where quantum effects occur in a sub-nanometer (sub-nm) real space with ultra-fast time and frequency resolutions. Classical metrology technologies face challenges, due to failure to achieve such a transient resolution. In response to the cutting-edge issue, a precision patterning sub-nanometrology relied up a pico-meter quantum sensing approach was developed to satisfy a precision sub-nanometrology need, wherein a conducting atomic force microscopy (C-AFM) coupling a laser micro-photoluminescence (micro-PL) spectroscopy was a state-of-the art height-current-phase uncertainty correlation reproducible traceable precision sub-nanometrology technology with a powerful pico-meter (pm) spatial resolution associated with transient quantized pico-ample differential current-nominal voltage resolutions relied up a quantum electrical measurement triangle principle. A self-assembled vertical nanomedicine photoluminescence crystal array with an atomic interference effect was revealed in Figure 1 and a quantum regenerative amplification principle was discussed. It is concluded that a precision patterning sub-nanometrology relied up a pico-meter quantum sensing approach provides a new impetus for an integrated circuit scaling and paves a way towards developing quantumlevel self-alignment patterning technologies to support precision quantum sensing and metrological device innovations and beyond, which are important for quality-profit upgrades and global industry developments.

We investigate utilizing nonlinear metamaterials for generating entangled photons with expected characteristics. Metamaterials are artificial structures with unique properties which are not attainable with naturally existing materials. In recent years, owing to high designability and flexibility, metamaterials have been deeply investigated and utilized for constructing novel photonic devices. Through tailoring the nanostructures of metamaterials with feasible nonlinear optical character, we can control the PDC process inside the medium to generate desirable photon states. Various spatial perturbations of optical parameters with special distributions can be introduced in via suitable arraying of elements of metamaterials. The spatial properties of entangled photons such as orbital angular momentum can be flexibly engineered. The nonlinear metamaterial provides a flexible platform for steering photonic entanglement.

We present how nonclassicality and entanglement can be characterized and detected efficiently for continuous variable systems. Of particular interest is the use of homodyne detections to measure quadrature amplitudes at minimum level to confirm nonclassicality and entanglement beyond Gaussian states. We introduce a systematic method for a functional form of uncertainty relations, which can be efficiently employed to experimentally detect non-Gaussian states comprehensively. Our approach for quantum correlations unifies a framework for quantum entanglement and quantum steering, which include the known results for Gaussian states and provides a better tool for non-Gaussian states than existing methods, e.g. entropic uncertainty relations.

Single-photon frequency conversion for quantum interface plays an important role in quantum communications and networks, which is crucial for the realization of quantum memory, faithful entanglement swapping and quantum teleportation. In this talk, I will present our recent experiments about single-photon frequency conversion based on quadratic nonlinear processes. Firstly, we demonstrated spectrum compression of broadband single photons at the telecom wavelength to the near-visible window. A positively chirped single-photon-level laser pulse and a negatively chirped classical one are converted to a narrowband single-photon pulse, with a spectrum compression factor of 58, through sum-frequency generation (SFG), marking a critical step towards coherent photonic interface. Secondly, we demonstrated the nonlinear interaction between two chirped broadband single-photon-level coherent states. A high SFG efficiency of 1.06 × 10−7 is realized, which may be utilized to achieve heralding entanglement at a distance. Finally, we theoretically introduced and experimentally demonstrated single-photon frequency conversion in the telecom band, enabling switching of single photons between dense wavelength-division multiplexing channels. Using cascaded quasi-phase matched sum/difference frequency generation, the signal photon of a photon pair from spontaneous down-conversion is precisely shifted to identically match its counterpart, i.e. idler photon, in frequency to manifest a clear non-classical dip in the Hong-Ou-Mandel interference. Moreover, quantum entanglement between the photon pair is maintained after the frequency conversion. Our researches have realized three significant quantum interfaces via single-photon frequency conversion, which hold great promise for the development of quantum communications and networks.

We theoretically investigate the detachment of silver anions by a few-cycle linearly polarized laser pulse. The results show that the angular distributions of photoelectron obtained by the strong-field approximation model are in good agreement with the recent experimental result. The photoelectron angular distributions are not dependent of the volume effect of a focused laser beam. More interestingly, based on the saddle-point method, the interference patterns in the photodetachment from silver anions are clearly clarified in detail.

Soliton self-frequency shift (SSFS) is a phenomenon that Raman self-pumping continuously transfers energy from higher frequency components of optical pulse to its lower frequency components. It has been explored over the last decades, because it has many potential applications in the fields of all-optical wavelength conversion, ultra-fast all-optical switch, all-optical de-multiplexing and so on. In this paper, Firstly, using split-step Fourier method for numerical simulation, it has been found that the soliton self-frequency shift increases with the increase of soliton peak power and nonlinear coefficient of the transmission fiber, and decreases with the increase of soliton width and group velocity dispersion. At the same time, third order dispersion is taken into account, which has a significant inhibitory effect on soliton selffrequency shift. Secondly, according to the existing conditions in the laboratory, self-frequency shift in a 2-km-long single-mode fiber has been experimentally studied, especially the influences of soliton peak power and optical fiber dispersion. A continuously tunable self-frequency shift with central wavelength from 4.29 nm to 43.25 nm has been achieved by adjusting the peak power of the soliton. It has been shown that the soliton self-frequency shift can be effectively tuned by flexibly adjusting the related parameters, which provides guidance for many practical applications of soliton self-frequency shift.

The optical frequency combs (OFCs) with widely and precisely tunable frequency spacing have several unique applications such as generation of microwave to terahertz signals, high-precision phase-coherent wavelength conversion, coherent wireless and wavelength division-multiplexed (WDM) communications. In recent years, a number of approaches have been proposed for OFCs generation (OFCG). Mode-locked lasers and microresonator can generate OFCs with large bandwidth and high stability but suffer from poor tunability because of their fixed resonator. An OFCG based on an optoelectronic oscillator (OEO) can generate OFCs with good tunability but has a complex configuration. Another typical type of OFCG is based on modulators. It is a potential and economic method due to its advantages of simplicity, stability and tunability. In this paper, a novel approach to generating optical frequency combs with widely and precisely tunable frequency spacing based on a double quadrature phase shift key (DQPSK) modulator and highly nonlinear optical fibers (HNLFs) is proposed and experimentally demonstrated. A DFB-LD seed laser at 1550nm is modulated by the DQPSK modulator which is driven by RF signals. 5-line OFCs are generated as the seed OFCs at the output of DQPSK modulator and then sent into a segment of HNLFs. In this scheme, the frequency spacing of OFCs is directly decided by the RF signals’ frequency, which can be widely and precisely tuned. Four-wave mixing (FWM) effect in HNLFs can effectively increase the number of comb lines and expand bandwidth of the seed OFCs without influence on frequency spacing. The configuration is relatively simple and adjustable. The frequency spacing can be precisely tuned from 10 MHz to 20 GHz in our experiments. The typical 25-line OFCs are experimentally generated with 432 GHz bandwidth at 16 GHz frequency spacing.

We proposed a method for ultra-high group index slow light with high optical buffering performance based on photonic crystal waveguide coupled with a cavity. By introducing cavity analogous to rhombus shape in photonic crystal waveguide center, slow light properties and buffering performance are studied. Numerical results through plane-wave expansion method and model field distribution through finite-difference time domain method show that both the rhombus cavity radii and some discriminatory rods around rhombus cavity have a plentiful effect on slow light properties and buffering fulfillment. By adjusting the cavity rod radii, we obtained high group index of 5163 with buffering bit length L_bit about 17.968 μm and delay time T_s reaching to 51.967 ps through the waveguide-cavity length of 3.02 μm. Moreover, low group velocity dispersion can be achieved, with governable positive and negative values. To regulate the optimal parameters to increase the group index and demonstrate the delay time performance, some discriminatory rods around rhombus cavity are adjusted in the upper and lower edges confronting each other in the waveguide, and ultra-high group index as exceedingly large as 22350 is obtained that is extremely higher than previous studies. Simultaneously, the corresponding buffer bit length Lbit and delay time Ts reach respectively to 25.8279 μm and 225.7783 ps through the waveguide-cavity length of 3.0306 μm. We designed a simple structure but a more generalized that may contribute a requisite theoretical basis for potential industrial applications in the storage capacity properties of high group index for optical buffering and optical communication systems.

We investigate effect of atomic densities (N) on propagation and spectral property of large area femtosecond Gaussian pulse (the pulse area is larger than 2π) in a three-level Λ-type atomic medium by using the numerical solution of the full Maxwell-Bloch equations without the slowly varying envelope and the rotating-wave approximations, and the solution is obtained by PC-FDTD method. It is shown that, variation of value of the atomic density has considerable effect on propagation and spectral property and the effect is closely relative to size of the pulse area. For the pulse with area 4π, propagate in the dilute medium with smaller atomic density, clear pulse splitting doesn’t occur, slight pulse spectrum broadening appears, the strength of the spectral component with higher frequency increases with the distance increasing; when the pulse propagates in the dilute medium with larger atomic density and in the dense medium, the main pulse splits into two sub-pulses, and the spectrum broadening in the dilute medium with larger atomic density is much larger than that in the dense medium. For the pulse with larger area 8π, the case of the pulse propagates in the dilute medium with smaller atomic density is similar to that of the 4π pulse; but when the pulse propagates in the dilute medium with larger atomic density and in the dense medium, the case is considerably different from that for 4π pulse, the main pulse splits into three sub-pulses, and the spectrum broadening in the dilute medium with larger atomic density is much smaller than that in the dense medium.

The ultra-stable microwave (USM) based on ultra-stable laser (USL) and fiber optical frequency comb (OFC) is built at the National Institute of Metrology (NIM), China. The OFC is stabilized with USL by controlling the pumping current and piezoelectric transducer (PZT). Meanwhile, the error signal is send to the temperature control of the optical resonant cavity for the long term locking which enable a more than 30 days continuously running. The second stability is 4E-15. By controlling the driving frequency of the AOM, the long term stability of H master is transmitted to the USM. This USM will be applied as the local oscillator for NIM5 Cs fountain to improve its short term stability.

A compact and flexible dual-wavelength eye-safe intracavity optical parametric oscillator (IOPO) configuration driven by a coaxially end pumped laser was proposed. Two fundamental waves were provided by a coaxially end pumped Qswitched dual-wavelength laser with combined two laser crystals, and the OPO cavity was placed inside the laser cavity for efficient conversion. Theoretical simulations showed that the power ratio for each signal wave, as well as the time interval between two pulses at different wavelengths, were both tunable by tuning the pump focusing depth or pump wavelength. Experimental results were performed with combined laser crystals (Nd:YAG and a-cut Nd:YLF) and a nonlinear crystal (KTA), demonstrating coincident conclusions. The maximum OPO output power was 724 mW (388 mW at 1506 nm and 336 mW at 1535 nm) with the LD pump power of 10 W at 6 kHz, corresponding to the opticaloptical conversion efficiency of 7.24%. As there was no gain competition between two fundamental waves, stable signal output could be obtained. Moreover, various wavelength pairs can be generated by using different laser crystal combinations. It is believed that this is a promising method for simultaneously generating dual-wavelength eye-safe lasers pulses.

Propagation of dichromatic femtosecond laser pulses tuned respectively in single-photon resonances with the cascade three-level system is studied. The initial areas of the two pulses are both equal to 2π, which makes them respectively an optical soliton in ideal two-level systems. When the dichromatic solitons are synchronized into the medium, both the temporal shapes and the spectral distributions of the pulses are strongly distorted during propagation. The delay time between the dichromatic solitons plays an important role on the evolution of the fields.

In the current work we demonstrate mode-locked fiber laser with automatic adjustment a coherence degree of the output pulses. As a source of the pulses we used 8-figure fiber laser with two amplifying fibers inside both loops of the laser cavity. Such configuration provides various pulsed regimes that have different degree of coherence from fully mode-locked single scale pulses to partly mode-locked double scale pulses. To search a pulsed regime with defined parameters we applied automatic genetic algorithm. To prove the feasibility of the genetic algorithm we applied it to find double – scale pulsed regimes with a fixed envelope duration of 50 ps and the contrast of the coherence peak in range of 0.02 – 0.5.

This work reports the results of research into mode-locked fibre lasers with non-trivial and controllable distribution of the radiation intensity along the resonant cavity. It is shown that local minimisation of non-linear optical effects and chromatic dispersion enables stable mode locking in ultra-long cavities and allows higher output pulse energies. Different configurations of fibre laser cavities, which may be promising for achievement of uniquely high pulse energies are discussed and analysed.

Focusing on the underwater exploration potential of lidar and the limitations of physical limit on its detection sensitivity and detection accuracy, this paper focuses on modeling and analyzing the ultra-sensitive detection performance of entangled Fock state under seawater attenuation environment. Based on the LCMMS state, the entanglement detection model under seawater attenuation environment is established. The minimum phase error accuracy of LCMMS under the uniform distribution of photon number and the interference fringe contrast formula are derived. The simulation results show that the ultra-sensitive detection distance of the entangled Fock state under clear seawater can reach a distance of more than ten meters under water. The high photon number entangled state can make the distance higher; because LCMMS contains more high In the M and M' state of the photon number, the ultra-sensitive detection range of the quantum interferometric target detection of LCMMS under seawater loss is nearly 1.3 times that of the M and M' state.

A synthetic photonic lattice (SPL) is a suitable test-bed to study dynamics of one-dimensional photonic mesh lattices. Unlike other realizations of photonic lattices, SPL possesses easy and fast control of optical potential and lattice parameters. Here we consider disordered synthetic photonic lattice with random variation of coupling ratio between the fiber loops in time. We numerically study dynamics of synthetic photonic mesh lattices with the randomly varying coupling ratio and observe that the pulse train circulating within the loops becomes localized next to the initial pulse position, while amplitude distribution has exponential form consistent with Anderson localization theory.

Theoretical calculations of the output characteristics about the periodically poled crystals-based intra-cavity second harmonic generation of the resonant wave in the singly resonant optical parametric oscillator (IC-SHG-SRO) are presented. Under the collimated Gaussian beam approximation, simple models are set up and the outputs of the IC-SHGSRO are shown theoretically. The calculations based on the experimental parameters are in good agreement with the experimental results. The output characteristics of the 532 nm green laser pumped IC-SHG-SRO resonating at 795 nm and the 1064 nm infrared laser pumped IC-SHG-SRO resonating at 1590 nm are predicted. The calculations demonstrate that there exists the optimum length of SHG crystal to obtain the maximum SH output for the given experimental conditions. These calculations and the models provide guidelines for designing and optimizing the continuous-wave ICSHG- SRO.

Single-photon avalanche diodes (SPADs) are widely used for practical applications requiring single-photon detection. The readout circuit, or quenching electronics, plays an important role for the operations of SPADs. Sine wave gating (SWG) is one of the key techniques for synchronous single-photon detection that can easily operate SPADs with a gating frequency as high as GHz level. Here we present a monolithic readout circuit for 1.25 GHz SWG SPADs. The monolithic chip, including a low-noise amplifier and two low-pass filters inside, is designed for weak avalanche extraction in the SWG scheme and fabricated using the technology of low temperature co-fired ceramic with a size of 15 mm × 15 mm. We then apply the monolithic chip into an InGaAs/InP single-photon detector (SPD). After the characterization both on the monolithic chip and the InGaAs/InP SPD, the functionality of the monolithic readout circuit is effectively verified. Implementing the monolithic integration of readout circuit is a key step towards developing miniaturized InGaAs/InP SPDs.

Atomic coherence and interference play an important role in the study of the atom-photon interactions. Electromagnetically induced transparency (EIT) is an extensively studied two-photon coherence phenomenon theoretically as well as experimentally. EIT is mainly observed in three-level atomic systems which causes transparency by quenching absorption of the medium. In this paper, based on the lambda type three-level system including energy level |1>, |2> and |3>, a microwave driving field is introduced between the excited-state energy level |3> and another excited-state energy level |4> to form an inverted Y-type four-level system. We theoretically study the two- and three-photon coherence in this system. The results show that the coupling field makes the probing absorption intensity at the resonant frequency have a very narrow line-width depression, i.e., EIT. The microwave field causes a dynamic Stark splitting of the energy level |3> and induces the Aulter-Townes double peaks. Their frequency interval is exactly equal to the Rabi frequency of the microwave field. The presence of all three fields induces wide window of EIT at the line center owing to the enhanced depression results. The transient evolution is also discussed to understand the optical switching process in the system. Our theoretical study will be helpful to get a deeper insight into the three-photon effects in multilevel systems.