This PDF file contains the front matter associated with SPIE Proceedings Volume 11558, including the Title Page, Copyright information, and Table of Contents.

A Monte-Carlo simulation was performed on the efficiency of random quasi-phase matching (RQPM) nonlinear optical frequency conversion in polycrystalline materials to show the detailed influence of the statistical grain morphology properties. The simulation took second harmonic generation (SHG) for example and considered the parameters of beam size, beam distribution, fundamental wavelength variation, polycrystalline average grain size (mean), standard deviation (Std), etc. The results and conclusions could enrich the theory of RQPM and provide guidance for polycrystalline material processing and sample selection for specific nonlinear-optical experiments.

Optical tweezers have found applications in many areas, the nonlinear effects play a significant role in femtosecond laser trappings. Here, we demonstrated that the traps are determined by the longitudinal electric field component due to the Kerr effect in nonlinear optical tweezers. Furthermore, we used a linearly polarized femtosecond laser as the trapping source to study the intrinsic bistability effect in nonlinear optical tweezers. A bistable state is demonstrated where the critical value shows big difference in incident power up- and down- sweeping process, showing a novel prospective in future.

The control of optical properties by electric means is the key to optoelectronic applications. For atomically thin two-dimensional (2D) materials, the natural advantage lies in that the carrier doping could be readily controlled through the electric gating effect, possibly affecting the optical properties. By exploiting this advantage, we studied nonlinear optical responses from doped graphene, including both coherent nonlinear processes such as the second harmonic generation (SHG) and third harmonic generation (THG), and the incoherent ultrafast photoluminescence (PL). The demonstration of these broadband, electrically tunable nonlinear optical responses in graphene is promising for a host of nonlinear optical applications. [1] T. Jiang et al., Nat. Photon. 12, 430 (2018). [2] Y. Zhang et al., Phys. Rev. Lett. 112, 047401 (2019). [3] D. Huang et al., Nano Lett. 16, 7985 (201

Optical resonators with cubic nonlinearity were among the first simplest physical systems proposed for generation of squeezed states of light as well as for verification of quantum nondemolition measurement concept. These conventional squeezed states are characterized with Gaussian statistics and positive Wigner function and are frequently treated as semiclassical. In contrast, it is known that the quantum states resulting from the higher order self-phase modulation are characterized with negative Wigner function. Such states can be transformed to an imperfect Fock state via classical biasing. Using these known features, we have developed an experiment strategy for observation and characterization of the nonclassical state in a system based on a high-Q nonlinear optical microcavity. We discuss technical limitations for the state observation associated with the losses in the system and technical noise of the classical optical sources involved in the measurement.

The on-chip scale devices are an appealing technology for diverse application, such as all-optical signal processing, frequency metrology, spectroscopy and sensing as the advantages of low cost, compact size and reduced power consumption. By capitalizing the strong optical nonlinearity and reasonable dispersion control of the Ge₂₈Sb₁₂Se₆₀ chalcogenide waveguides, we demonstrate the process of the supercontinuum spectrum generation on the chip and obtain the mutual verification results with the numerical simulation, revealing insights into the soliton dynamics and providing critical device design guidelines. A home-built, palm-sized femtosecond laser centering at 1560nm wavelength was used as the pumping source. Therefore, our work can provide a reference template for future waveguide design and research, such as on-chip Raman soliton source and on-chip optical frequency comb.

Quantum measurement is inevitable to extract information from quantum systems. Exploring the power and limitation of quantum measurement has profound implications not only to foundational studies, but also to many practical applications. In most of these tasks, many identically prepared quantum systems are measured to acquire sufficient information. Although there is no entanglement or even no classical correlation among these identically systems, surprisingly, quantum collective measurements on them may extract more information than local measurements on individual systems, thereby leading to higher efficiency and precision in these tasks. Although the significance of collective measurements has been recognized for two decades, it is still very challenging to demonstrate their advantage in experiments. Here, we will introduce the first implementation of quantum collective measurement and it's applications on quantum orienting, reducing quantum backation of measurement, and so on.

In this talk, I shall discuss the recent developments on measurement-device-independent quantum key distribution, including the ones based on single detection. Meanwhile, I shall also present some of the experimental realizations.

Optical non-reciprocity for weak light field is particularly important for chip-based photonic and quantum information process. By adopting the strong nonlinearity associated with a few atoms in a strongly coupled cavity QED system and an asymmetric cavity configuration, we experimentally demonstrate the nonreciprocal transmission between two counterpropagating light fields with extremely low power. The system can be further manipulated to realize a non-reciprocal cavity polariton. Such that an optical isolation exceeds 30dB on single-quanta level and non-reciprocal non-classical statistics with coherent probe lights can be obtained, manifesting the quantum nature of the non-reciprocal polaritons.

We propose a scheme for realizing spatial Kramers-Kronig (KK) relation of probe susceptibility in a cold atomic sample driven by a linearly modulated control field. The sample is found to exhibit broken, transitional, and unbroken regimes, where the non-Hermitian KK relation is well satisfied, foreshortened, and fully destroyed in order. The unbroken and transitional regimes are of special interest because they allow unidirectional reflection at one and both sample ends, respectively. Bragg scattering can also be incorporated into spatial KK relation to largely enhance the nonzero reflectivity, leading thus to a high forward-backward reflectivity contrast.

This Conference Presentation, “Novel photonic quantum CNOT gates on the silicon chip,” was recorded for the Photonics Asia 2020 Digital Forum.

Privacy amplification (PA) is an essential process for high-speed and real-time implementation of a continuous-variable quantum key distribution (CV-QKD) system. This work focuses on the improvement of the performance of PA, and we realize PA with Toeplitz matrix and accelerate it using fast Fourier transform (FFT) on graphic processing unit (GPU). Based on the architectural feature of FFT, we adjust its form of input length and obtained an average speed of PA about 2Gbps with input length ranges from 1Mbits to 128Mbits, which is length-adaptable to satisfy various requirements of CV-QKD systems at different transmission distances. Furthermore, we test this work with different compress ratios of PA, which can also achieve a high implementation speed around 2Gbps. With the method used in this paper, the requirements of PA for the high-speed and real-time CV-QKD system can be entirely satisfied.

By the numerical analyzing and simulation, we investigate effect of carrier envelope phase on propagation of femtosecond chirped Gaussian laser pulse in a dense three-level Λ-type atomic medium. It is shown that, when the small area 2π negative chirped pulses (or the 2π positive chirped pulses) with different value of initial carrier envelope phase φ₀ propagate in the medium, splitting don’t occur and the chirped pulses evolve gradually to approximate normal Gaussian pulses with equal amplitude and group velocity, and the phase differences between them remain the same as the case of initial input pulses. When the 4π negative chirped pulses with different φ₀ propagate in the medium, the pulses will split into at least two sub-pulses and the amplitude of the first sub-pulse is far more than the second sub-pulse; These first sub-pulses have equal amplitudes and propagating with equal group velocity in the medium, and the phase differences between these first sub-pulses remain the same as the case of initial input pulses; The amplitudes of these second sub-pulses are not equal and don’t change monotonously with linearly increasing of φ₀ but take on a invert S-shaped pattern, and the phase differences between these second sub-pulses are different. The case of 4π positive chirped pulses is similar to the case of 4π negative chirped pulses, but the amplitudes of these second sub-pulses split off from the 4π positive chirped pulses have no obvious changes compared with the case of 4π negative chirped pulses.

The interference resonant propagation of two-color 4π-4π femtosecond Gaussian pulses in three-level Λ-type atomic medium with different values of the relative phase φ is investigated by using numerical solution, which is obtained by the finite-difference time domain (FDTD) method and the iterative predictor–corrector (PC) method for the full Maxwell-Bloch equations. It is found that, for a smaller value of the φ, the pulse splitting occurs, and when the value of the φ increases to a certain value, only the variation of pulse shape present but the pulse splitting no longer occurs; accordingly, their spectral strengths and frequency ranges of the two-color pulses decrease remarkably with the value of φ increasing; Moreover, the relative phase also has an obvious effect on population, different population evolutions can be achieved by adjusting the value of φ.

Rescattering induced by intense laser fields is one of the dominant processes in strong-field physics. It was usually described classically or semiclassically. In the present work, we show that the fanlike structures exist in photoelectron momentum distributions even though using the strong field approximation model with the short-range potential. We also investigate the dependence of fanlike structures on the laser intensity. We have performed the detailed analysis on the photoelectron momentum distributions through the quantum-orbit theory.

In this paper, a novel experimental preparation scheme of Gaussian modulated coherent state (GMCS) in continuous variable quantum key distribution (CVQKD) system is proposed based on dual-drive Mach-Zehnder modulator (DDMZM). The experimental implementation of the proposed GMCS preparation scheme only depends on a DDMZM instead of an AM and a PM in conventional CVQKD, which simplifies the experimental setup and reduces the costs of the CVQKD system. Moreover, the sum-difference signals of the Rayleigh distribution and uniform distribution are applied on two parallel electrodes of the DDMZM, respectively, getting rid of the accurate time-delay alignment between the AM and the PM in conventional Gaussian modulation scheme. Besides, the measurement method of the prepared GMCS is experimentally demonstrated based on heterodyne detection, and both quadrature (X and P) are simultaneously measured to verify the proposed GMCS preparation scheme.

For the first time demonstrated are possibilities of control over the duration of sub-pulses within nanosecond noise-like pulse bunches, from 1.4 ps to 170 fs, through spectral filtering of radiation. The proposed method is implemented on the basis of an actively mode-locked Yb fibre laser. Prospects of electronic control over sub-pulse duration are analysed and practical applications are further discussed, in which sub-pulse duration may be important.

This report analyses possible mechanisms of conversion of noise-like laser pulses into coherent ones with comparatively high efficiency. It is demonstrated that incoherent or partly coherent pulses can be promising for phase-insensitive pumping in processes where the structure of pumping pulses is not related to the structure of generated/transformed pulses. Among applications that leverage such processes may be mentioned, for example, passively mode-locked pulse generation, supercontinuum generation in a nonlinear amplifier, as well as some others. Efficient conversion of noise-like laser pulses into coherent solitons enables attractive prospects of application of localised noise-like wave objects capable of carrying relatively high energies.

Throughput of error correction is the bottleneck of the postprocessing for continuous-variable quantum key distribution system. In this paper, a shuffled iterative decoding method is proposed to reduce the number of iterations for error correction. For three typical code rate, i.e., 0.1, 0.05, 0.02, our results show that the maximum decoding speed is up to 72.86 Mbits/s, 53.96 Mbits/s and 42.45 Mbits/s, respectively, which significantly improves the real-time processing capacity of continuous-variable quantum key distribution system.

A hybrid mode-locked Er-doped fiber laser based on single-walled carbon nanotube saturable absorber and nonlinear amplifying loop mirror (NALM) is constructed. At 1564.5 nm, the mode-locked laser is self-started by carefully adjusting the polarization controller, with the repetition frequency of 16.24 MHz, 3-dB spectral width of 8.5 nm and pulse width of 302 fs. Compared with the laser only utilizing single-wall carbon nanotube saturable absorber or NALM mode-locked Er-doped fiber laser, the hybrid one has narrower output pulse width and the mode-locking state is more stable.

We build a new two-way fiber time transfer technique (TWFTT) simulation model, and simulate controllable asymmetric attack of delay and attenuation. Both asymmetric attacks can make the clock in the remote module slower by attacking the 1pps signal from local to remote side. Otherwise, the clock will be faster. In this paper, the asymmetric delay attack can linearly control the synchronization error from 0 to 300 ps. The asymmetric attenuation attack can adjust the synchronization error from 0 ~ 302.7 ps with the controllable attenuation from 0 to 2.8 dB. Moreover, we find that the time interval counter change greatly when the system is attacked. The research has a significant meaning in defense of such asymmetric attacks.

A new type of electro-optic crystal (PIN-PMN-PT) has been discovered. It has similar transmission wavelength range and transmittance with the traditional lithium niobate crystal. It has higher electro-optic coefficient and refractive index than lithium niobate crystal. We used this material to make a disk-shaped whispering gallery structure and studied it.