Phase-shifting mask design for interference exposure of chirp blazed grating

An interference exposure system using a phase-shifting mask was proposed for generating periodic sawtooth optical intensity profile with chirp in period. Multiple space-harmonic waves are launched from the mask by diffraction, and the sawtooth optical intensity is formed by interference based on Fourier synthesis after propagation through an air gap. The design concept merely utilizing positive diffraction-order harmonics with tilt illumination of an exposure light and a design algorithm based on time-reversed configuration for calculating required phase shift amount were proposed and discussed. A phase-shifting mask for a blazed grating of very high chirp rate was designed to demonstrate its potential and feasibility. The grating period changes from 2.2 to 3.1 μm gradually within 0.3 mm length. Sawtooth-like optical intensity profile was confirmed by theoretical simulation as well as preliminary experimental results.     

红外多目标复合模拟器光学系统设计

详述了适用于3～5μm波段、长入瞳距多目标复合的投影光学系统设计。系统实现了干扰和目标发生器共用一个投影光学系统,入瞳距大于2000mm。原理上采用目标系统、干扰系统、主投影系统分开设计,并在主投影系统焦平面上放置中间像面实现目标和干扰的复合。给出了最后的设计结果,包括点列图、调制传递函数曲线。入瞳距2050mm,入瞳口径Φ75mm,视场±2°。     

A novel reconfigurable radio-over-fiber system based on flexible optical devices

In this paper, a reconfigurable Radio over Fiber system based on optical switches, optical multimode interference power splitter and tunable optical filters is designed, which can achieve quadrature phase shift keying wireless modulation in optical domain and switch carrier frequency between 30 and 60 GHz. The scheme can make good use of bandwidth resource and realize signal transmission in fiber within 10 km.     

Influence of Fano interference and incoherent processes on optical bistability in a four-level quantum dot nanostructure

Role of Fano interference and incoherent pumping field on optical bistability in a four-level designed In Ga N/Ga N quantum dot nanostructure embedded in a unidirectional ring cavity are analyzed. It is found that intensity threshold of optical bistability can be manipulated by Fano interference. It is shown that incoherent pumping fields make the threshold of optical bistability behave differently by Fano interference. Moreover, in the presence of Fano interference the medium becomes phase-dependent. Therefore, the relative phase of applied fields can affect the behaviors of optical bistability and intensity threshold can be controlled easily.     

光学玻璃弹性模量的自动化测量方法

针对现有光学玻璃弹性模量测量周期长、测量过程复杂等问题,提出了一种利用计算机图像处理技术快速测量小样品光学平板玻璃弹性模量的方法。基于接触力学理论和牛顿环干涉原理推导出测量光学玻璃弹性模量的解析式,利用图像处理技术的优势,通过摄像头拍摄牛顿环干涉图像,设计MFC监控与单张图片拍摄界面程序,自动测量牛顿环干涉图像中心黑斑半径,最后根据光学玻璃弹性模量与牛顿环干涉图像中心黑斑半径及牛顿环中心应力之间的关联关系,实现小样品光学玻璃弹性模量的快速测量。实验结果表明:在应力31.17 N～55.11 N范围内,光学玻璃弹性模量的测量相对误差不超过±8.8%;在应力55.11 N～71.07 N范围内,测量相对误差不超过±16%。     

High sensitivity micro-displacement homodyne interferometry北大核心CSCD

Interferometry is widely used in nano-scale micro-topography measurement. In order to improve its accuracy and sensitivity, a high-sensitivity homodyne interferometry based on white light interference and laser secondary interference was proposed. A high-sensitivity homodyne interferometry system was designed, and the zero point of the laser secondary interference was used to locate the dark striation of white light interference, so that it could reach the maximum slope when optical path difference was zero. The signals of white light and laser were analyzed by using the wave principle and intensity formula of interference fringes, and a sensitivity calculation method based on the combination of white light and laser interference signal was proposed. The system and its sensitivity were simulated. Finally, the optical path was built, and the white light interference fringes were adjusted to the dark striations position, so as to locate the zero position of laser secondary interference and carry out the data acquisition. It is showed that the sensitivity of the measurement method is at least 1 832 times higher than that of the laser secondary interference, and the corresponding measurement uncertainty is only ±0.288 7 mV. The measurement system can effectively solve the problem of large amount of calculation in traditional interferometry, and has high sensitivity, stability and reliability. Copyright ©2022 Journal of Applied Optics. All rights reserved.     

电光相位体调制器驱动电路

根据电光相位体调制器的结构特征,设计了一个驱动电路,该电路主要由OP37和PA84组成,具有结构简单、性能稳定的特点。经实验测定能够在0～280 kHz频率范围内实现峰-峰值200 V的电压输出。设计了对输出信号进行相位补偿的方法,完成了光相位调制实验。利用光电探测器,检测到了由电光相位体调制器驱动电压变化所引起的干涉条纹的变化。     

螺旋Blumlein脉冲形成线的放电分析

利用拉普拉斯方法严格求解双电报方程,得到了内外线传输时间不相同的螺旋Blumlein脉冲形成线在纯电阻负载上输出电压波形的解析表达式,分析并讨论了螺旋Blumlein脉冲形成线内线传输时间等于外线、小于外线和大于外线等3种情况下输出电压的特点,同时与波过程分析方法进行了比较,结果完全一致。研究结果表明,对于内外线非等传输时间的螺旋Blumlein脉冲形成线,与传统Blumlein脉冲形成线相比,具有其显著的特点。     

Diffractive interferometer for visualization and measurement of optical heterogeneities

New optical arrangements of the two beam diffractive interferometer with the inverted wave fronts and the combined optical branches based on zone plates are proposed. The special software is designed. The restitution of an interference pattern is performed; the skeleton of fringes is selected; the graphic visualization of optical heterogeneity of a sample is built in the computer-aided processing of interferograms. Proposed DI enable visualizing the optical thickness heterogeneities in the transparent sample, measuring them with accuracy ～0.05λ and can be used for research and quality surveillance of laser crystals and other optical materials.     

干涉条纹相位锁定系统分析及其控制

干涉条纹的相位变化与干涉条纹中某一固定点的光强密切相关,基于这一原理,通过对干涉场光强分析,提出并设计了一种用于干涉条纹相位锁定的控制系统.光电探测器检测干涉条纹中固定目标点的光强,并以该光强电压作为反馈控制信号,利用声光调制器对干涉系统中两束高斯光束中的一束进行实时频率调制,将光强电压控制在一个固定值,实现干涉条纹的相位锁定.构建了条纹锁定控制系统控制对象的理论模型,通过实验进行了验证,并基于该模型的特点设计了条纹锁定控制器.实验结果表明:在400Hz的控制频率下,干涉条纹相位漂移不超过±0.04个条纹周期,满足干涉光刻的曝光需求.     

Single-mode rib polymer waveguides and electro-optic polymer waveguide switches

Mode-matching and effective index methods are used to analyze single-mode operation of optical rib polymer waveguides. Their single-mode waveguiding conditions are determined. Single-mode rib waveguides fabricated from guest–host polyetherketone are presented. The estimated propagation loss of straight rib-waveguides is 0.7 dB/cm at 1.55 μm. Furthermore, by using the mode field-transfer matrix method, 2×2 and 4×4 polymer Mach–Zehnder interference switch operating at 1.55 μm wavelength has been designed based on optical multi-mode interference.     

基于弹光调制的红外光谱吸收法在室内VOC检测中的研究

为了保证静态干涉系统在气体定性定最分析方面稳定性高、抗干扰能力强的特点,设计了基于弹光调制实现光程静态扫描的干涉检测系统.系统由红外激光器、起偏器、弹光调制器、检偏器及CCD组成.通过弹光调制器使弹光晶体的主折射率随调制信号周期性的变化,从而产生周期性变化的光程差.通过对调制相位变化的计算,可知得到调制度随晶体长度、调...     

MGTI型光交错复用器的色散特性分析

基于多光束干涉和Michelson干涉的共同作用原理,设计了畸变最小,高信道隔离度,宽且平坦通带,高一致性的MGTI型50 GHz光交错复用器.由于G-T腔对光波相位的非线性调制,使该器件具有固有的相对其它同类器件大的色散,在分析器件的色散特性的基础上,提出了该类器件的色散补偿方案,经补偿后的器件能够满足实际高速系统要求.     

基于光干涉法的光学玻璃应力测量方法研究

以平板理论为基础,利用牛顿环应力变形导致干涉图样的微小变化,提出一种基于光干涉法测量玻璃体应力的无损测量方法。理论推导出牛顿环曲率半径与应力之间的变换关系,利用自行设计的可安装在牛顿环仪上的施压装置,实验研究了施加应力与干涉图样的变换关系,通过理论分析与实验比较,证明了用牛顿环干涉法测量应力的可行性。利用该装置及方法对光学玻璃试样的应力进行测量,测量结果与实际施加的应力进行比较,误差最小为0.8%。     

激光全息干涉法测量二元气体扩散系数

依据Mach-Zehnder干涉光路搭建了数字实时激光全息干涉实验台,设计加工了适用于测量二元气体扩散系数的扩散槽本体,详细介绍了根据物光相位的变化计算二元气体扩散系数的测量原理及图像处理方法。在此基础上测量了二元气体对H_2-Air、CH_4-Air和O_2-Air在273.15 K和0.1 MPa下的扩散系数,通过与文献值的比较验证了该实验方法的准确性,为后续二元气体扩散系数测量工作奠定了坚实的基础。     

实现微位移测量的非本征法布里-珀罗干涉型光纤传感器

从光纤耦合和多光束干涉的原理出发,建立了非本征型法布里_珀罗干涉仪光纤传感器的理论模型,得到了用光谱法进行绝对距离测量的公式。设计出了传感器探头的结构,并搭建了系统。用LED作为宽带光源所得到的反射光谱可用于实际样品的微位移测量。实验结果表明,该传感器理论模型的数值模拟结果与实验结果是一致的。对实验数据进行了误差分析,所得到的测量精度可达到1μm。     

干涉条纹密度的计算及其应用研究

采用光的干涉方法检测曲面光学表面的加工质量时,都需要事先设计好系统光路的最佳检测技术参数,并能对检测的难度进行有效的评估,从而确保检测的精度。该研究采用了一种计算干涉条纹密度的新方法,对任意光学曲面检测的难度进行评估,并用于确定球面参考光点光源的最佳位置。以非球面为例,计算了非球面的最接近球面的半径和最大非球面度以及非球面检测时球面参考光点光源的最佳位置,说明了计算干涉条纹密度方法在确定干涉检测系统光路调试最佳条件的优越性,可为各种干涉检测系统的设计以及优化调试过程提供理论依据和分析指导。     

基于多级微镜的傅里叶变换成像光谱仪干涉成像系统分析与设计

为了实现傅里叶变换成像光谱仪的静态化与高通量,提出一种基于多级微镜的时空混合调制成像光谱仪,其干涉系统是利用一个多级微镜代替迈克尔逊干涉仪中的平面镜,其显著特点是无运动部件和限制系统光通量的狭缝,可同时获得目标的干涉图与二维空间图像。该成像光谱仪利用前置成像系统将目标成像到干涉系统的平面镜与多级微镜上,利用多级微镜的结构特点对两成像光束的光程差进行调制,然后通过后置成像系统获得不同干涉级次的目标图像。首先通过对该成像光谱仪干涉系统光谱信噪比的分析,明确了光谱信噪比与图像信噪比之间的关系,确定了多级微镜的特征参数。为了确保每个阶梯面所对应光程差的恒定性,通过对前置成像系统成像过程的分析,确定了前置成像系统像方远心的光路结构;通过对系统视场角与光程差之间关系的分析和计算,确定了前置成像系统的设计指标并完成了光学设计。为了保证后置成像系统不引入额外的光程差,通过对后置成像系统成像特点的分析,确定了后置成像系统双远心的光路结构;通过对系统入射孔径角与阶梯级数之间关系的分析和计算,最终设计出满足系统性能需求的后置成像系统。通过对各单元系统的理论分析与光学设计,为静态化与高通量成像光谱仪的发展提供了一种新的思路。     

Probe frequency- and field intensity-sensitive coherent control effects in an EIT-based periodic layered medium

A periodic layered medium, with unit cells consisting of a dielectric and an electromagnetically-induced transparency (EIT)-based atomic vapor, is designed for light propagation manipulation. Considering that a destructive quantum interference relevant to a two-photon resonance emerges in EIT-based atoms interacting with both control and probe fields, an EIT-based periodic layered medium exhibits a flexible frequency-sensitive optical response, where a very small variation in the probe frequency can lead to a drastic variation in reflectance and transmittance. The present EIT-based periodic layered structure can result in controllable optical processes that depend sensitively on the external control field. The tunable and sensitive optical response induced by the quantum interference of a multi-level atomic system can be applied in the fabrication of new photonic and quantum optical devices. This material will also open a good perspective for the application of such designs in several new fields, including photonic microcircuits or integrated optical circuits.     

光学设计性实验研究

介绍PASCO实验平台在光学设计性实验中的应用。在PASCO实验平台上设计并完成了单缝衍射、双缝干涉和偏振等实验。用软件对数据采集处理,得出光强与位置关系曲线图。展示了PASCO平台在光学设计实验中的便捷与优势。