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This combination allows for a satisfactory tolerance to the initial guess in the pose tracking phase. The experimental results demonstrate the feasibility of the proposed method.Multifocal diffractive lenses are used widely in ophthalmology. This paper provides a general mathematical formula to summarize various multifocal diffractive lens designs and introduces a novel, design the subzonal multifocal diffractive (SMUD) lens. Analytical and numerical methods of SMUD lens design are elaborated in detail. A number of trifocal and quadrifocal SMUD lens designs of high diffraction efficiency are presented. Fresnel zone spacing factors are introduced to take into account the incidence of a converging or diverging beam and the curvature of the substrate on which the diffractive surface is created. Apodization and ophthalmic astigmatism correction related to diffractive lenses are also discussed.In this paper, one-dimensional (1D) photonic crystals (PCs) based on InSb and nonlinear materials are studied using the transmission matrix method. It is found that in the terahertz band, due to the magneto-optical characteristics of InSb, when the incident light propagates through such 1D PCs in two different directions (forward and backward propagation), an asymmetric optical bistable state can be obtained. Propagating from the forward direction, the bistable state is achieved. Spreading from the backward direction, the multistable state can be observed. Compared with the bistable threshold value for the case of forward incidence, the similar value that appeared in the multistable curve is significantly reduced. The polarization-sensitive features of the asymmetric optical bistability of the presented 1D PCs are also investigated under TM waves, which focuses on the tuning effects of incident angle, external magnetic field, temperature, and the thicknesses of the InSb and nonlinear dielectric layers on the asymmetric optical bistability. The results show that when the incident light enters from two different directions, the tailoring effects of the incident angle and thickness of the InSb layer on the bistable state are obviously different, but the tuning influences of the magnetic field, temperature, and the thickness of the nonlinear material layer on the bistable state are similar. The asymmetric optical bistability we made in this paper can be applied to multifunctional devices and nonreciprocal optical isolators.Improving the bit resolution is a major challenge for the photonic quantization schemes based on the phase shifting of modulation transfer functions of Mach-Zehnder modulators (MZMs), since their quantization levels are limited to be 2N, where N is the number of employed modulators or optical channels. selleck chemicals In this paper, we propose a novel, to the best of our knowledge, resolution-enhanced photonic quantization scheme, in which the input analog signals are quantized based on the intensity-weighted modulation transfer functions. By using N-wavelength sampling, 2N weighted modulation transfer functions and 2N+1 quantization levels can be obtained with only two MZMs. Hence, the proposed scheme can greatly improve the system bit resolution with a relatively simple configuration. A proof-of-concept experiment of a 17-level quantization system is carried out, which fully verifies the feasibility of the approach. Meanwhile, the performance degradation induced by the errors in the bias phase and the power deviation of sampling pulses is discussed. In addition, the performance limitation induced by the sampling source and dispersion-induced broadening is also investigated.The phase diversity (PD) algorithm is an image-based co-phasing error detection method for segmented mirror synthetic aperture optical systems. Particle swarm optimization (PSO) is suitable for PD for its fast convergence speed and simple structure. However, with the increase of the numbers of subapertures, optimization of cost function formed by the PD algorithm becomes a high-dimension non-linear optimization problem, which would lead PSO to result in a premature solution. Regarding the problem above, this paper presented a modified PSO in the PD algorithm to co-phase the segmented primary mirror, which overcame drawbacks of the traditional PSO, such as premature convergence and deactivation of particles, and enhanced the dig ability of the algorithm. Vast simulation results show that the modified PSO in the PD algorithm can effectively restore the segmented primary mirror, reducing the peak-to-valley (PV) value to 0.0012λ and the root mean square error to 0.0007λ, and raising the Strehl ratio to over 0.999. A comparison was also conducted to show that the modified PSO has advantages over two existing algorithms in higher accuracy and faster convergence speed.A laser diode (LD) pumped intracavity chemical vapor deposition (CVD) diamond cascade Raman laser is reported here. By rotating a Brewster plate (BP) in the laser resonator, the Raman laser with tunable output coupling rate is achieved. The highly compact diamond laser emitted 1240 nm and 1485 nm Stokes light simultaneously via optimization of the pumping direction. The slope efficiency of the intracavity diamond laser is improved by optimizing the output coupling rate and adjusting the repetition rate of the 1064 nm fundamental laser. Ultimately, the maximum slope efficiency of the first Stokes light (1240 nm) is 16.8%, and the corresponding output power is about 0.6 W. The maximum peak power is 2.5 kW when the power of 808 nm LD is 34.7 W.In this paper, a multipoint temperature measurement scheme based on Fabry-Perot interferometers (FPIs) multiplexing is proposed. The FPI sensor is constructed as a section of hollow-core fiber (HCF) partially filled with polydimethylsiloxane (PDMS) spliced to a single-mode fiber. An array-waveguide grating with 16 channels is used for the FPI sensors' multiplexing and demultiplexing, and a broadband source is used as the light source. The corresponding theoretical model was built for analysis of the scheme, and the simulation results shown the FPI working principle can be simplified as a dual-beam interference. Two channels connected to two FPI sensors were experimentally tested for the concept verification. The temperature sensitivities of the proposed two sensors are 1.090 dB/°C and 1.210 dB/°C from 30°C to 40°C, respectively. There is no interchannel cross talk observed. Hence, FPI temperature sensors can work simultaneously in this structure, proving the validity of the multipoint temperature measurement concept.