Noninvasive optical control of complex semiconductor laser dynamics

Time-delayed feedback control (TDFC) is transferred to the optical domain and applied to complex multisection semiconductor lasers as used in optical communication. Pyragas-type control is provided by purely optical feedback from an external Fabry-Pérot interferometer. This all-optical setup needs no time-consuming signal processing and, thus, has practically no speed limit. Proof-of-principle experiments demonstrate noninvasive stabilization of unstable steady states, chaos control, and suppression of noise-induced oscillations on picosecond time scales. A Lang-Kobayashi type model with optical TDFC is investigated taking into account the dynamic details of the device as well as all-optical time-delayed feedback. The parameter regimes that allow for stabilization of stationary emission are mapped out in good agreement with the experiments. Including noise, an analytical expression for the power spectral density is derived, which is confirmed by the experimental all-optical suppression of noise-induced relaxation oscillations.     

光学纳米测量方法及发展趋势

综述了光学方法中以频率跟踪方法、外差干涉仪、调频干涉仪、偏振干涉仪和光学光栅为代表的光学纳米测量方法。分析了它们的发展状况以及各自特点,指出建立适合于纳米测量的纳米环境是目前亟待解决的关键性问题,给出了光学纳米测量方法的发展方向和在设计测量系统时应该注意的问题     

Generation of optical vector beams with a diffractive optical element interferometer

We present a novel approach to generating radially and azimuthally polarized vector beams that utilize an interferometer constructed from two identical diffractive optical elements. The measured polarization properties of four vector beam states and their phase relationships are in good agreement with theoretical expectations. This interferometer is passively phase stable and robust, making it suitable for linear and nonlinear optical (superresolution) microscopy.     

光纤白光干涉仪等臂长技术研究

介绍了几种光纤干涉仪等臂长技术,比较了各自的优缺点和适用范围,对光纤干涉仪的平衡有较大的参考价值。     

“宋”望远镜夏克哈特曼光学系统设计

根据中国宋标准节点望远镜系统要求,设计了用于望远镜波前误差测量的夏克哈特曼（S-H）传感器光学系统。从望远镜衍射极限成像和观测星等要求出发,对S-H的采样点数选取和波面重建精度进行分析计算,根据所选微透镜阵列和宋望远镜光学参数进行S-H准直镜的消像差设计,采用两组双胶合透镜实现了480 nm~680 nm波长范围的系统衍射极限成像。设计的系统能够实现6等星的目标测量,测量精度0.05。根据设计结果搭建了实验系统,对主镜初始状态和校正之后的波前误差进行了测量,并将S-H测量结果与4D干涉仪测量结果进行了比较。实验结果表明:所设计S-H系统测量精度0.008 m（RMS）,能够满足宋望远镜的技术要求。     

关于光学元件面形评价参数峰谷值(PV)的分析

 光学元件的表面面形或波前质量一般采用数字指标峰谷值PV(表面最高点和最低点之差)来评价。而两点PV在高分辨率干涉仪的测量结果中具有很大不确定性。为了更准确地评价光学元件的表面面形或波前质量,讨论了针对两点PV进行改进后的评价方式PV20,PVr,PVq。通过模拟实验证明其可以描述真实波面,并在实验中证明其可以消除灰尘等杂点对测量结果带来的干扰,以及这几种评价方式对CCD分辩率的变化不敏感,并发现上述3种方式在测量重复性方面也有较好的表现。     

GRIN透镜干涉仪光学系统模型和分析

较完整地提出GRIN透镜干涉仪的数学模型,分析了光学系统处于六种不同模态下的特点,讨论了有关结构因素,特别是GRIN透镜长度对干涉仪工作性能的影响,有关分析和相关结论可作为GRIN透镜干涉仪系统设计和测量计算的依据。     

“宋”望远镜夏克哈特曼光学系统设计

 根据中国“宋”标准节点望远镜系统要求,设计了用于望远镜波前误差测量的夏克哈特曼（S-H）传感器光学系统。从望远镜衍射极限成像和观测星等要求出发,对S-H的采样点数选取和波面重建精度进行分析计算,根据所选微透镜阵列和“宋”望远镜光学参数进行S-H准直镜的消像差设计,采用两组双胶合透镜实现了480 nm~680 nm波长范围的系统衍射极限成像。设计的系统能够实现6等星的目标测量,测量精度0.05"。根据设计结果搭建了实验系统,对主镜初始状态和校正之后的波前误差进行了测量,并将S-H测量结果与4D干涉仪测量结果进行了比较。实验结果表明：所设计S-H系统测量精度0.008 μm（RMS）,能够满足“宋”望远镜的技术要求。     

Real-time phase-resolved functional optical coherence tomography by use of optical Hilbert transformation

We have developed a novel real-time phase-resolved functional optical coherence tomography system that uses optical Hilbert transformation. When we use a resonant scanner in the reference arm of the interferometer, with an axial scanning speed of 4 kHz, the frame rate of both structural and Doppler blood-flow imaging with a size of 100 by 100 pixels is 10 Hz. The system has high sensitivity and a larger dynamic range for measuring the Doppler frequency shift that is due to moving red blood cells. Real-time images of in vivo blood flow in human skin obtained with this interferometer are presented.     

An experimental investigation of the optical switching characteristics using an optical Sagnac interferometer incorporating one and two ring resonators

We present the use of a fiber optic Sagnac interferometer incorporating one and two fiber optic ring resonators to characterize experimentally the optical switching behaviors. These prototypes were formed by the Sagnac interferometer and serially connected to the ring resonators. The input optical signal was launched via one end of the interferometer, where the polarization control was employed to obtain the maximum optical transmission power. Results obtained have shown that the increasing in switching time (i.e. narrower spectral width) and power can be achieved.     

Optimal interferometer designs for optical coherence tomography

We introduce a family of power-conserving fiber-optic interferometer designs for low-coherence reflectometry that use optical circulators, unbalanced couplers, and (or) balanced heterodyne detection. Simple design equations for optimization of the signal-to-noise ratio of the interferometers are expressed in terms of relevant signal and noise sources and measurable system parameters. We use the equations to evaluate the expected performance of the new configurations compared with that of the standard Michelson interferometer that is commonly used in optical coherence tomography (OCT) systems. The analysis indicates that improved sensitivity is expected for all the new interferometer designs, compared with the sensitivity of the standard OCT interferometer, under high-speed imaging conditions.     

A novel optical subdivision method for dual-frequency interferometer

The theory of optical subdivision techniques of dual-frequency laser interferometers is stated. And a novel optical subdivision technique is proposed originally to enhance resolution of a commercial interferometer by adding some corner-cubes. Then the performance of the interferometer is tested. The interferometer resolution of 1.24 nm and the average error of below 2 nm are achieved by using the technique. The most novel of the optical subdivision technique is without λ/4 plates. It is less sensitive to environmental changes, it has prodigious potential to improve resolution farther and it can reduce polarization mixing error.     

Power-efficient Fourier domain optical coherence tomography setup for selection in the optical path difference sign using Talbot bands

A power-efficient Fourier domain optical coherence tomography fiber system is presented free of mirror terms. The object and reference beams from the interferometer are spatially separated to illuminate different parts of the diffraction grating in the spectrometer according to a method inspired from the use of Talbot bands. In this way, the system is made sensitive to only one sign of the optical path difference in the interferometer.     

干涉法测量Cymbal换能器的等效压电常量

在光学平板上用分立光学元件构建了迈克耳孙型分光束干涉仪,利用优化工艺制备的Cymbal换能器件作为核心单元,利用其在电场下的位移放大作用驱动平面反射镜,引起干涉图样的变化,实现了微位移及Cymbal换能器件等效压电常量的测定,并进行了非定域干涉图样变化的动态演示.     

Atomic Bloch-Zener oscillations and Stückelberg interferometry in optical lattices

We report on experiments investigating quantum transport and band interferometry of an atomic Bose-Einstein condensate in an optical lattice with a two-band miniband structure, realized with a Fourier-synthesized optical lattice potential. Bloch-Zener oscillations, the coherent superposition of Bloch oscillations and Landau-Zener tunneling between the two bands, are observed. When the relative phase between paths in different bands is varied, an interference signal is observed, demonstrating the coherence of the dynamics in the miniband system. Measured fringe patterns of this Stückelberg interferometer allow us to interferometrically map out the band structure of the optical lattice over the full Brillouin zone.     

从迈克耳孙干涉仪到光学相干层析术

介绍了迈克耳孙干涉仪在物理学发展史上的重要作用及生物医学成像技术的发展状况．从迈克耳孙干涉仪的发展过程出发,讨论了光学相干层析术的原理、特性及其在生物医学成像、物理学、材料科学中的应用,并将频谱光学相干层析术与傅里叶变换光谱术作了比较,最后讨论了它在教学上的意义．     

使用子孔径拼接法检测大口径光学元件

为了解决大口径光学元件检测过程中成本高、空间分辨率低这两个主要难点 ,提出了使用小口径、高精度干涉仪分次检测大口径元件 ,然后通过优化算法将检测结果进行拼接处理 ,最终得到原大口径元件波前信息的方法 ,并作了初步的拼接模拟实验 ,确认了这一方案的可行性。     

Soliton squeezing in a highly transmissive nonlinear optical loop mirror

A perturbation approach is used to study the quantum noise of optical solitons in an asymmetric fiber Sagnac interferometer (a highly transmissive nonlinear optical loop mirror). Analytical expressions for the three second-order quadrature correlators are derived and used to predict the amount of detectable amplitude squeezing along with the optimum power-splitting ratio of the Sagnac interferometer. We find that it is the number-phase correlation owing to the Kerr nonlinearity that is primarily responsible for the observable noise reduction. The group-velocity dispersion affecting the field in the nonsoliton arm of the fiber interferometer is shown to limit the minimum achievable Fano factor.     

Remote cure monitoring of epoxy materials using optical techniques

A remote all-optical technique for the generation and detection of ultrasonics in materials is described. This technique uses a robust wideband optical fiber interferometer for detection. Using this interferometer, non-contact measurements of ultrasonic propagation times in epoxy materials are reported throughout the complete cure cycle.     

System for measuring optical admittance of a thin film stack

A new method based on the polarization interferometer structure has been applied to measure the optical admittance, the refractive index and thickness of a thin film. The structure is a vibration insensitive optical system. There is one Twyman-Green interferometer part to induce a phase difference and one Fizeau interferometer part to induce the interference in the system. The intensities coming from four different polarizers were measured at the same time to prevent mechanical vibration influence. Using the polarization interferometer, the optical admittance, the refractive index and thickness of a single layer of Ta₂O₅ thin film has been measured. The measurement results were compared with the results obtained by ellipsometer. The results meet reasonable values in both refractive index and thickness.