All-reflective Michelson, Sagnac, and Fabry-Perot interferometers based on grating beam splitters

All-reflective Michelson, Sagnac, and Fabry-Perot interferometers based on grating beam splitters are experimentally demonstrated at a wavelength of 1064 nm. A 1200-groove/mm grating diffracting 0 and -1 orders with an efficiency of 48.2% for each order was used as a near-50/50 beam splitter. The all-reflective Sagnac and Michelson interferometers were formed by reintroducing both of the diffracted beams back to the grating. The Fabry-Perot interferometer was formed in a Littrow configuration by using a 1700-groove/mm grating with a blazing efficiency of 91% as a cavity coupler. These interferometers encompass all the fundamental configurations of all-reflective laser interferometric gravitational-wave detectors, promising improved wave-front quality by avoiding volume thermal effects in transmissive optics under high-power laser illumination.     

Thermodynamic phase noise in fibre interferometers

Phase noise due to thermodynamic fluctuations in the optical path length is evaluated in this paper for basic fibre interferometers. In Mach-Zehnder and Michelson interferometers, where the temperature phase fluctuation (TPF) is that intrinsic to the fibre, this noise has been reported to be comparable to shot noise and a possible limit to sensor sensitivity in practical cases. We show that in Sagnac interferometers, used in fibre gyro and in Faraday current sensors, the TPF noise is decreased with respect to that intrinsic to the fiber because propagation in the same optical path leads to a correlation of the phase fluctuations. In addition, we show that in Fabry-Perot and ring resonators, as multiple reflections increase the effective path length, TPF noise is enhanced and can be dominant over shot noise even for moderate fibre lengths.     

The Sagnac effect: 20 years of development in matter-wave interferometry

Since the first atom interferometry experiments in 1991, measurements of rotation through the Sagnac effect in open-area atom interferometers have been investigated. These studies have demonstrated very high sensitivity that can compete with state-of-the-art optical Sagnac interferometers. Since the early 2000s, these developments have been motivated by possible applications in inertial guidance and geophysics. Most matter-wave interferometers that have been investigated since then are based on two-photon Raman transitions for the manipulation of atomic wave packets. Results from the two most studied configurations, a space-domain interferometer with atomic beams and a time-domain interferometer with cold atoms, are presented and compared. Finally, the latest generation of cold atom interferometers and their preliminary results are presented.     

环形光纤声发射传感器的相位调制特性研究

提出了一种基于光纤Sagnac干涉仪的环形传感器，用于固体表面传播的超声波的检测.这种传感器的特点是能够精确地检测由固体表面传播的超声波产生的微弱振动.当超声波信号通过光纤传感器的两个臂到达探测器时，干涉仪的输出光强度受到了超声信号的调制.通过检测干涉仪的输出光强度并利用Fourier变换，测得了超声信号的振幅和频率.而且对传感系统的位相调制特性进行了仿真，并对实验结果进行了分析，结果表明该系统可用于固体表面传播的超声波频率特征的识别.     

Non-contact detection of laser-generated surface acoustic waves using fiber optic Sagnac interferometer

A high powered Q-switched Nd:YAG laser was used to excite the surface waves, and an optical fiber sensor was used to detect the out-of-plane displacements due to the propagating waves. This sensor is based on the fiber optic Sagnac interferometer, which has the path-matched configuration and does not require active stabilization. Quadrature phase bias between two interfering laser beams in the Sagnac loop is applied by controlling the birefringence in an optical path using a fiber polarization controller. A stable quadrature phase bias can be confirmed by observing the interferometer output according to the change of phase bias. Additional signal processing is not needed for the detection of ultrasonic waves using the Sagnac interferometer. The performance of the fiber optic Sagnac interferometer was investigated, and laser-generated surface wave signals were detected using this fiber optic sensor. The developed fiber optic sensor configured in this study is very simple and is effective for non-contact detection of ultrasonic waves.     

Sagnac干涉仪的几何参量计算

根据空间调制干涉成像光谱仪对视场的要求和小型化目标,通过对分体型Sagnac干涉仪的结构与光路进行分析,研究了Sagnac干涉仪的几何参量与入射光线视场角和孔径之间的关系.推导出满足视场要求的最优化几何参量以及满足横向剪切要求的几何参量修正量,并将其推广到实体型Sagnac干涉仪中,用于指导干涉成像光谱仪的结构设计与优化.     

Backward influence of the interference signal from the sensors of physical quantities on the radiation intensity spectrum of a low-coherent source

We consider specific features of optical-circuit operation in the presence of radiation which is returned to the source after having passed an optical path exceeding the initial coherence length of the reference wave when, as was previously assumed, the delay modulation should not influence the oscillation mode. However, experiments with the Michelson and Sagnac fiber interferometers showed that intensity modulation of the interference signal and, therefore, intensity modulation of the source radiation related to the active-medium nonlinearity appear when the interfering waves with the phase-difference modulation return. The revealed effect leads to distortion of a signal at the interferometer output irrespectively of the delay time and can be removed by placing an optical isolator at the source output.     

A ruggedized miniature UHV electron biprism interferometer for new fundamental experiments and applications

Electron interferometers are very sensitive to mechanical vibration and alternating magnetic fields. This is the reason why in the past their application was restricted to laboratories with very low disturbances of this kind. We present a novel type of electron biprism interferometer totally different in its technical realisation compared to conventional instruments. Its extremely low sensitivity to both types of disturbances is demonstrated and for the first time allows to make use of electron interferometry in virtually every environment. Experiments inconceivable with conventional electron interferometers are rendered possible with the new instrument. As an example, we hope to be able to demonstrate with it the rotational phase shift of charged matter waves (Sagnac effect with electrons) in the near future.     

Demonstration of a recombined Fabry-Perot-Michelson interferometer with suspended mirrors

We describe preliminary experimental results concerning the operation of a 3 m arm-length Michelson interferometer with two Fabry-Perot cavities whose mirrors and beam splitter are suspended independently by wires. The reflected light beams from the two Fabry-Perot cavities are recombined to obtain interference at a photo-detector; this scheme is necessary for future power-recycled laser interferometers used to detect gravitational waves. The fundamental properties of the interferometer are presented, including the power spectral density of the displacement noise.     

干涉光纤电流传感器

提出了一种新型的高压电流光纤传感器,由Sagnac干涉仪和光路构成,采用Labview编写虚拟仪器的测试端软件。该系统利用法拉第效应,借助电子电路,获得干涉后输出光强信号中一次谐波成分,就可以将高压母线中待测电流的大小和相位分量测出。由于采用的新颖的双光路设计,与通常的干涉仪相比该系统的动态测量范围扩大数百倍,而且系统不受外界缓变量的影响。     

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.     

光纤干涉仪臂差的测量

用白光干涉和Michelson干涉仪技术测量光纤Michelson干涉仪和Mach-Zehnder干涉仪的臂差.这种方法能在线测量任意长度的光纤干涉仪臂差,包括零臂差,测量的精度由光源的相干长度确定,为微米数量级.     

Compact phase-shifted Sagnac interferometer for ultrasound detection

A compact fibre, phase-shifted Sagnac interferometer for ultrasound detection has been developed. The interferometer is a truly path-matched device, and therefore requires no path stabilization or heterodyning. It is a less expensive and more robust alternative to the heterodyne or path-stabilized Michelson interferometer. The device provides high spatial resolution of ultrasonic detection. It has been used in conjunction with conventional piezoelectric transducers (PZT) to detect Rayleigh and Lamb waves and to image a crack in a thin plate, rivet cracks in riveted plates, and for ultrasonic beam profiling.     

Sagnac effect in ring interferometers on “slow” waves

We consider the Sagnac effect in ring interferometers on magnetostatic and surface acoustic waves. It is shown that the Sagnac effect for waves of arbitrary type (including both magnetostatic and surface acoustic waves) propagating in an arbitrary medium cannot be calculated using Galilean transformations but is explained within the framework of the special relativity and is related to the difference between the phase velocities rather than group velocities of counter-propagating waves in the rotating reference frame. We also show that the phase difference of counterpropagating waves due to the Sagnac effect depends on neither the phase velocity of the wave in a medium at rest nor the dispersion of the medium; it depends only on the wave frequency and the angular velocity of interferometer rotation. The minimum angular velocity that can be measured in the ring interferometers using magnetostatic and surface acoustic waves is estimated. N. I. Labachevsky State University, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 4, pp. 373–382, April 1999.     

A microprism array as shearing device for speckle shearing interferometry

In most speckle shearing interferometers image shearing is performed by means of a Michelson interferometer or by means of a wedge prism covering half of the aperture of the camera objective. We present a speckle shearing interferometer which utilizes a microprism array for this purpose. It is placed between the test specimen and the camera. In comparision with a wedge prism it exhibits some advantages: it needs no exact alignment, it works with any camera lens, the shearing distance and direction of shearing can be easily changed by changing position (resp. angular orientation) of the element. Phase stepping for computer evaluation of the speckle shearing interferograms is performed by the translation of the shearing element. A special translation stage was developed. Experimental results are presented. The interferometer is suited for microcomponent and microsystem testing.     

一种3×3Sagnac光纤高压电流传感器的设计

提出了一种新颖的光纤干涉型电流传感器结构 ,对其工作原理进行了分析 ,导出了其光路部分的数学模型 ,并通过实验验证了该传感器设计的合理性。与法拉第磁光效应的光纤电流传感器相比较 ,该传感器能自动补偿光纤固有的双折射和温度等环境变化产生的干扰以及光源幅度噪声的影响等优点 ;与一般干涉仪相比其工作动态范围可以扩大数百倍。     

基于全光纤萨格纳克干涉仪的温度不敏感磁场测量

研究了双折射磁光光纤萨格纳克 (Sagnac) 干涉仪透射谱的磁场和温度敏感性. 实验表明, 干涉仪透射谱会随着温度的增加向短波长移动 (温度系数为-0.435 nm/℃), 其波长依赖性则随着磁场的增加而降低. 据此, 通过调节干涉仪内偏振控制器状态实现了温度不敏感的磁场测量, 磁场系数为189 mW/T², 实验结果与理论分析一致. 关键词： 磁场测量 磁光效应 双折射 萨格纳克干涉仪     

高灵敏度的量子迈克耳孙干涉仪

迈克耳孙干涉仪不仅可以用来研究物理学的基本问题,而且能够用于精密测量,比如引力波信号的测量.因此,构建高灵敏度的迈克耳孙干涉仪是实现微弱信号测量的关键.目前,人们利用压缩态可以降低迈克耳孙干涉仪的噪声;通过光学四波混频过程能够放大马赫·曾德尔干涉仪中的相位信号,从而提高干涉仪的信噪比和灵敏度.本文研究了一种用于高灵敏度相位测量的量子迈克耳孙干涉仪.在迈克耳孙干涉仪中,利用非简并光学参量放大器取代干涉仪中的线性光学分束器;并且将压缩态注入干涉仪的真空通道,可以得到高信噪比和高灵敏度的干涉仪.由于存在不可避免的光学损耗,分析了迈克耳孙干涉仪内部和外部的损耗对相位测量灵敏度的影响.通过理论计算研究了干涉仪的相位测量灵敏度随系统参数的变化关系,得到了高灵敏度的相位测量量子迈克耳孙干涉仪的实现条件,为用于精密测量的干涉仪的设计提供了直接参考.     

Absolute distance measurement by using modified dual-wavelength heterodyne Michelson interferometer

This study proposes a modified dual-wavelength heterodyne Michelson interferometer for measuring the absolute distance that can avoid the influence of wavelength drifts. This modified interferometer consists of two conventional Michelson interferometers. A standard plate is introduced in one arm of one Michelson interferometer. The phase differences of p- and s- polarization test lights in the two interferometers can be measured accurately by dual-wavelength heterodyne interferometry. Hence, the absolute distance can be determined by substituting the phase differences into special derived equations. Meanwhile, the test lights suffer from the same wavelength drift effect. Therefore, the negative effect caused by the drift can be offset, and the measurement stability can be significantly increased. The feasibility of this method was demonstrated with a measurement resolution of about 1.36 μm. Additionally, this method has a simple structure, easy operation and rapid measurement.     

A simple high-sensitivity interferometric position sensor for test mass control on an advanced LIGO interferometer

A small Michelson interferometer has been configured as a tracking mirror displacement sensor in order to achieve both large dynamic range (2.1 mm) and excellent sensitivity across a broad frequency range (6Hz–3 kHz). The interferometer is illuminated by a simple LED, uses broadband, non-polarising beamsplitters and contains no lensing optics. A DC-coupled balanced detector provides an error signal that is used to position the tracking mirror of the Michelson interferometer so as to maintain an interferometer operating position close to the centre of a particular fringe. The total interferometric sensor provides a small, simple and cost-effective means of achieving high-resolution displacement measurements.