光纤低相干干涉测量法的光谱域处理技术

使用低相干、宽带光源可以让光纤传感器系统获得高分辨率和大动态范围.光谱域处理技术在具有这种特点的光源下应运而生.该技术的特点是除了使用传感干涉仪以外,还必须用第二个处理干涉仪来提取所需的条纹图样信息.使用交叉的梳状谱也是其特点之一.使用这种技术的光纤传感器系统可以实现多种物理量的测量,而且其结构简单、成本低廉.     

光程差倍增的纳米级精度激光干涉仪

介绍了一种新型的纳米级精度位移测量激光干涉仪。提出了耦合差动干涉的新方法。通过对光程差进行倍增 ,提高了干涉仪的分辨率和稳定性。该干涉仪结构简洁紧凑 ,光路布局对称性好 ,不存在死光程 ,容易装调 ,符合阿贝原则和结构变形最小原则 ,在 10 mm (可以扩展至 50 mm )测量范围内 ,获得了λ/16 0 0的分辨率和纳米级的测量精度。     

Spectrally stable Er-fiber laser for application in phase-sensitive optical time-domain reflectometry

A high degree of frequency stability in an Er-fiber laser with the Fabry-Perot configuration was achieved using a long (25-km) optical-feedback loop. The frequency-drift rate was determined to be <1 MHz/min by observing temporal fringes in an unbalanced Mach-Zehnder interferometer. Instantaneous linewidth measured with a delayed self-heterodyne interferometer was less than the 3-kHz resolution limit. The laser was utilized in an optical time-domain reflectometry experiment to detect and locate a time-varying phase perturbation applied to an optical fiber.     

Optical displacement measurement with GaAs/AlGaAs-basedmonolithically integrated Michelson interferometers

Two monolithically integrated optical displacement sensors fabricated in the GaAs/AlGaAs material system are reported. These single-chip microsystems are configured as Michelson interferometers and comprise a distributed Bragg reflector (DBR) laser, photodetectors, phase shifters, and waveguide couplers. While the use of a single Michelson interferometer allows measurement of displacement magnitude only, a double Michelson interferometer with two interferometer signals in phase quadrature also permits determination of movement direction. In addition, through the use of two 90° phase-shifted interferometer signals in the latter device, a phase interpolation of 2π/20 is possible, leading to a displacement resolution in the range of 20 nm. The integration of these complex optical functions could be realized with a relatively simple fabrication process     

Sagnac fiber interferometer with the population grating for fiber Bragg grating dynamic strain sensing

A Sagnac fiber interferometer with the population grating formed in saturable erbium-doped fiber (EDF) for fiber Bragg grating (FBG) dynamic strain sensing is proposed. In this configuration, a semiconductor optical amplifier (SOA)-based fiber ring laser with an FBG reflector is employed in the sensing part and a Sagnac interferometer based on transient two-wave mixing (TWM) via dynamic population gratings in single-mode polarization maintaining erbium-doped fiber (PM-EDF) is used in this detecting part. Experimental results show that the Sagnac fiber interferometer detection system can stably respond to dynamic strains at high frequencies. As an example of application, the response of the sensor system to continuous sinusoidal ultrasonic signals is presented. The proposed simple and robust configuration has an all-fiber design based on commercially available elements, which makes it promising for applications in fiber optic ultrasonic sensors.     

光栅多普勒纳米干涉仪

用横向塞曼激光作光源构成的 Dammann光栅多普勒干涉仪有利于降低热膨胀影响 ,测量过程中干涉臂长不变、便于克服折射率漂移 ,具有 0 .7nm分辨率。分析了光栅退偏效应的影响 ,与差动双频激光干涉仪进行了比对。实验结果表明 ,光栅间距光学 8细分等间隔 ,当光栅栅距为 2 0μm时其测量非线性误差不超过 2 5nm。     

A novel electronically scanned white-light interferometer using aMach-Zehnder approach

A theoretical analysis and experimental evaluation of a novel Mach-Zehnder interferometer (MZI), used as a recovery interferometer in an electronically scanned white-light interferometer is reported. This modified version of a MZI has the advantages of being very simple and compact, with high stability and does not introduce any spatial “misoverlapping” of the beams. In addition, since only one beamsplitter is employed in the interferometer (instead of the usual two used in a conventional MZI), the system is relatively easy to implement and at low cost. Furthermore, this configuration can be simply set to cover a wide range of optical path difference values by simply changing the angle and position of one of the mirrors. This gives the interferometer the advantage of being easily adapted far a range of different measurement applications     

Application of a fiber Fourier transform spectrometer to thedetection of wavelength-encoded signals from Bragg grating sensors

We describe an all-fiber Fourier transform spectrometer for decoding the wavelength shifts from a series of Bragg grating sensors. The system described uses an optical fiber Michelson interferometer with one arm wrapped on a piezoelectric driven stretcher capable of inducing a ~10 cm fiber length change. Passive polarization compensation is utilized which eliminates the possibility of random polarization fading in the interferometer causing apodization of the interferogram. This permits an all-fiber design without the need for speciality optical fiber or external polarization adjustments. A reference Nd:YAG laser is used to stabilize the interferometric scan in a phase-locked loop configuration by way of slow and fast feedback correction elements. A spectral resolution of <0.07 cm^-1 was obtained, which corresponds to a Bragg wavelength shift of ~0.015 nm in the 1.55 μm region. The simultaneous wavelength determination capacity of the device also permits it to be used in a variety of other applications for analysis of optical spectra     

光纤Mach-Zehnder干涉仪系统的研究

介绍了光纤Mach-Zehnder(MZ)干涉仪系统的结构,阐述了该系统中信号光与参考光的干涉原理以及影响干涉光强的因素,分析了光纤耦合器的交叉耦合和PZT的作用,描述了光纤偏振控制器的结构、工作原理及其对光纤Mach-Zehnder干涉仪系统传感臂偏振态的控制,最后介绍了光纤Mach-Zehnder干涉仪系统的应用。     

基于法布里-珀罗低相干干涉的绝对距离测量系统

提出了一种基于光纤法布里-珀罗低相干干涉的 绝对距离测量系统,不仅能对绝对距离进行测 量,而且还能对温度、压力、应力等量进行绝对测量。系统利用闪耀光栅将来自法布里-珀 罗干涉仪的低相 干干涉信号进行散射,使不同波长的干涉信号由线阵CCD 不同的像元探测。利用CCD探测到 的干涉信号 相邻波谷的波数差得到法布里-珀罗干涉仪的腔长,从而实现绝对距离测量。与其它低相干 干涉测量系统相 比,此系统无需扫描干涉仪的光程,一次成像即实现测量。测量系统简单,测量速度快,对 静态物理量和 动态物理量都能进行测量。系统的光纤结构使得它还能进行远程测量。实验结果表明系统对 绝对距离测量的分辨率可达3.317 nm,10次重 复测量的标准差为10.7 nm。     

单次曝光显微剪切全息干涉仪

本文所介绍的干涉仪具有全息记录光路简单、自动保证基本等光程、所记录的波前可以在不同的参考背景中复现等项特点,适用于有很高时空分辨要求的干涉测量.     

632.8nm高精度移相菲佐干涉仪测量误差分析

为了满足高精度光学系统对光学元件纳米级的检测精度要求,提出了一种理论可实现纳米级测量的632.8nm移相菲佐干涉仪的设计方案。通过对检测凹面和凸面的632.8nm移相菲佐干涉仪的基本结构和测量原理的分析,指出影响干涉仪测量精度的几种主要误差:移相误差、几何结构误差、振动误差、探测器误差(非线性误差和量化误差)、光源误差(波长不稳定和强度不稳定)、空气扰动和折射率变化误差。通过对这些误差理论分析和模拟,量化了各误差对测量精度的影响,其中移相误差、几何误差、振动误差和空气折射率误差影响最为显著。根据测量精度要求和仿真结果,得到实现纳米级测量的干涉仪系统参数和环境参数设置要求。     

基于半导体光放大器和取样光纤光栅结合Sagnac环的多波长光纤激光器

Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavelengths with 1.8 nm spacing have been generated stably at room temperature.The proposed laser has the advan-tages such as removal of the high-cost circulator,flexibility in channel-spacing tuning,and simple all-optical fiber configuration,which has potential applications in high-capacity wavelength-division-multiplexed(WDM)systems and mechanical sensors.     

一种测量液体旋光特性的共光路外差干涉技术

为了提高旋光特性检测的灵敏度,设计搭建了一套基于塞曼效应的共光路外差干涉仪应用于旋光液体的旋光特性检测.采用塞曼效应激光器作为光源能发出两束正交线偏光,简化了实验装置的复杂性;且在系统中利用平衡检测与差动放大器,可降低激光器本身与外部环境所造成的大部分噪声,从而提高检测灵敏度.结果表明,对(0～50)mg/dL的低浓度葡萄糖水溶液的旋光特性测量,其检测灵敏度可达2.3×10-5(°).这种结构简单的干涉仪可应用于固态、液体或气态旋光物质的旋光特性分析中.     

用于测量微机械部件振动的光纤斐索干涉仪

提出一种结构简单、使用方便的用于微电子机械部件运动状态测量的光纤斐索干涉装置。考虑到光纤出射光束的发散,在有效反射率中引入了损耗因子,讨论了它的基本工作原理。为了提高测量精度和最小可探测距离,光纤控头固定在一个ＰＺＴ上作可控调制。用屯喇叭膜片在多种驱动条件下的运动状态２,进行了数据处理和讨论。     

Monolithic integration of an all-optical Mach-Zehnder demultiplexerusing an asymmetric twin-waveguide structure

We demonstrate monolithic integration of a twin-waveguide Mach-Zehnder terahertz optical asymmetric demultiplexer (MZ-TOAD). The InGaAsP-InP device operates at 1.55 μm wavelength and has two semiconductor optical amplifiers in the asymmetric MZ interferometer configuration with a single control input and a built-in switching delay. A 28-ps full-width at half-maximum (FWHM) switching window with high contrast ratio for a range of control powers is obtained using a counter-propagating optical signal and control pulses     

光学相干层析系统色散的在线测量及补偿

针对光学相干层析(OCT)系统中迈克尔逊干涉仪两臂色散不匹配导致纵向分辨率的降低,提出了一种基于频域干涉及非线性曲线拟合的方法对干涉仪两臂色散差进行在线测量,根据测量结果在干涉仪一臂中加入非零色散位移光纤(NZDSF)对色散差进行补偿.实验结果表明,经过色散补偿后系统的纵向分辨率与理论值相符合,离体牙齿OCT图像的质量...     

Theoretical analysis of a push-pull fiber-optic hydrophone

A push-pull fiber-optic hydrophone is analyzed theoretically by closed-form approximations. The sensor is a fiber-optic Mach-Zehnder interferometer with a single-mode optical fiber from each arm wound on a separate tube. The two tubes are coaxial, with one tube inside the other. The acoustic medium is applied to the inside (outside) of the smaller (larger) diameter tube with the fiber wound on the tube's opposite side. This configuration is desired so that the acoustic signal modulates the optical phase of the arms with equal magnitude 180° out of phase. This gives the sensor twice the sensitivity of an analogous single tube sensor. The heat sinked interferometer arms with equal and opposite sensitivities are in relative close proximity to each other. This promotes good noise rejection to achieve a low minimum detectable acoustic pressure due to the interferometer's common-mode rejection.     

Characteristic analysis of a novel F-P interferometer based on a pair of FBGs with built-in LPFGs

The transmission characteristics of a Fabry-Pérot (F-P) interferometer based on a fiber Bragg grating (FBG) pair with a built-in long-period fiber grating (LPFG) are theoretically analyzed, and the shift of transmission interference fringe as a function of environmental refractive index is acquired. The influence of the lengths of F-P cavity, LPFG and FBG on the transmission characteristics of the proposed interferometer has been numerically investigated, and the simulation results indicate that the sensitivity of refractive index reaches 2.27 × 10-6 for an optical spectrum analyzer (OSA) with a resolution of 1 pm.     

基于偏振合束的相移雅满剪切干涉仪

相移雅满横向剪切干涉仪非常适合于达到衍射极限的光束的波面检测。为了改进现有的在两路剪切光束中直接插入起偏器的相移雅满剪切干涉仪,提出了一种基于偏振合束的相移雅满剪切干涉仪。该剪切干涉仪利用雅满平板前后表面的反射进行分束并形成两路干涉光束,两路干涉光束分别通过剪切平板后偏振合束并进行偏振移相。它保持了常规雅满剪切干涉仪的光路结构,提高了剪切干涉图的对比度,不再存在插入起偏器引入测量误差的问题。构建了改进前、后的两种相移雅满双剪切干涉仪,并进行了相应的对比实验,实验结果很好地验证了基于偏振合束的相移雅满剪切干涉仪的实用性。