Michelson Interferometer Configuration Research Articles

Laboratory implementation of Fourier transform infrared (FTIR) spectrograph using a super-continuum laser

Fourier Transform infrared (FTIR) spectroscopy is a technique to indirectly measure the spectrum of electromagnetic wave over a broad range. The vibrational response signature will be revealed through the absorption spectrum. The super-continuum laser is the appropriate option for using as a light source of FTIR because of its broad spectral bandwidth and high spatial coherence, which could expand the observable region. In this work, a custom design of laboratory prototype of FTIR system using a super-continuum laser with a wavelength in the range of 1500 – 2 400 nm (6667 – 4167 cm−1) is presented. The system was designed to have a combination of monochromatic and broadband interferometers in a free space Michelson interferometer configuration. An interferogram of a monochromatic laser at 532 nm (18 797 cm−1) was used to correct the phase distortion in the interferogram of the broadband light source. The location of peaks and valleys of the monochromatic interferogram were used to resample the broadband interference signal. The resulting spectrum was analyzed and then compared to the theoretical spectrum for further performance improvements.

A Demodulation Scheme Based on Measuring Interference Fringe Visibility With a Highly Birefringent Fiber Based Michelson Interferometer

We propose a novel demodulation scheme based on measuring interference fringe visibility and demonstrate it using a typical Michelson interferometer (MI) configuration. The key component to achieve the scheme is a section of highly birefringent fiber (HBF) spliced into the sensing arm to function as the sensing element. The optical path difference (OPD) leads to interference fringes, while the birefringence of the HBF results in a visibility envelop. It is possible to detect measurands associated with birefringence through measuring the visibility, which is attributed to a flexible use of the fundamental principle of interferometry. As one of the potential applications, temperature sensing employing the MI configuration is performed. Moreover, the technique has the advantage of being immune to element instabilities, such as power fluctuation of the light source, phase shift of the reference arm, noise of the photo detector, and wavelength shift of the optical spectrum analyzer (OSA). This work may provide an alternative method to achieve high precision interferometry with low cost.

Design of All-Optical Half Adder and Half Subtractor based on SOA-MI

An all-optical half adder and half subtractor is proposed using Semiconductor Optical Amplifier assisted Michelson Interferometer (SOA-MI) configuration along with two similar Fiber Bragg Grating (FBG) at the end of the interferometric arms to satisfy the truth table of half adder and half subtractor. SOA acts as an amplifier without the need for conversion to electrical signals. The proposed model is designed using all-optical NOR gates with cross-gain modulation (XGM) of SOA at bit rate of 10Gbps. Analysis of performance factors which includes Bit Error Rate (BER), OSNR and Q-factor have been discussed.

Higher-order Hermite-Gauss modes as a robust flat beam in interferometric gravitational wave detectors

Higher-order Laguerre-Gauss (LG) modes have previously been investigated as a candidate for reducing test-mass thermal noise in ground-based gravitational-wave detectors like Advanced LIGO. It has been shown however that LG modes' fragility against mirror surface figure imperfections limits their compatibility with the current state-of-the-art test masses. In this paper we explore the alternative of using higher-order Hermite-Gauss (HG) modes for thermal noise reduction, and show that with the deliberate addition of astigmatism they are orders of magnitude more robust against mirror surface distortions than LG modes of equivalent order. We present simulations of Advanced LIGO-like arm cavities with realistic mirror figures which can support HG$_{33}$ modes with average arm losses and contrast defects in a Fabry-Perot Michelson interferometer configuration which are well below the typical measured values in Advanced LIGO. This demonstrates that the mirror surface flatness errors will not be a limiting factor for the use of these modes in future gravitational-wave detectors.

Approach for deformable mirror wavefront error correction

Adaptive optics (AO) is receiving wide applications for diffraction-limited imaging in astronomical observations and biomedical research. In an AO system, the deformable mirror (DM) is commanded to correct wavefront errors (WFEs) and is a key component. However, a DM may not be perfect, and it may have strong static WFEs, which may be inherited from the DM manufacturing process or be induced by external factors such as the vibration during the transportation of delivery, which must be corrected before it is integrated into an AO system. To correct this static WFE, we introduce a simple approach. Our approach is based on a two-beam Michelson interferometer configuration, in which a high-quality flat mirror is used as a reference mirror whose surface wavefront can be copied to that of the DM, and thus the DM WFEs can be effectively corrected through an optimization procedure. Our experiments demonstrated that this approach is simple to conduct. Using an iteration optimization approach, the Strehl ratio of the DM can be improved from the initial 0.198 to the 0.997, within 30 min of the optimization run.

Phase derivative thermo-spatiogram for distributed temperature sensing based on chirped grating-Michelson Interferometer

A novel thermometric measurement based on chirped fiber Bragg grating (CFBG) and Michelson Interferometer is proposed. The interrogation technique is based on the linear relation between the temperature and the phase derivative function of the grating, which is determined through Fourier transformation of the output spectrum. The Michelson interferometer configuration offers the flexibility in adjusting the position of coupling coefficient curve in the spatiogram, enabling the interrogation to be done at a shorter optical spectrum record length which can reduce the interrogation time and computation load.

Dual-core all-fiber integrated immunosensor for detection of protein antigens

An optical fiber interferometric microprobe for detection of specific proteins is presented in this paper. The microprobe is an all-fiber device, which is based on Michelson interferometer configuration, which allows for detection of protein antigens in an analyzed solution thanks to antibodies immobilized on the sensor surface. The interferometer is made of dual core fiber and has a precisely formed arm length difference, achieved by splicing a fragment of polarization maintaining fiber to one of the cores. An all-fiber configuration of the sensor decreases substantially cross-sensitivities to temperature and deformation in comparison to other optical fiber interferometers. Reported sensor has a sensing region on the tip of the interferometer and therefore may be used for point measurements in medicine. The immunosensor and optical measuring system are designed to utilize the most common broadband light sources that operate at a central wavelength of 1.55 µm. The results show that it is possible to detect a protein antigen present in a solution by using an all-fiber interferometer coated with specific antibodies. The resulting peak shift can reaches 0.6 nm, which is sufficient to be measured by an optical spectrum analyzer or a spectrometer. A model allowing for estimation of the value of lower limit of detection for such sensors has been elaborated. The elaborated detection system may act as a framework for detection of various antigens and thus it can find future applications in medical diagnostics.

THE CONTRIBUTION OF THE AN/TPS-3 RADAR ANTENNA TO AUSTRALIAN RADIO ASTRONOMY

The CSIRO Division of Radiophysics used the WWII surplus AN/TPS-3 radar dishes for their early solar radio astronomy research and eclipse observations. These aerials were also used in a spaced (Michelson) interferometer configuration in the late 1940s to investigate solar limb brightening at 600 MHz. This work paralleled early solar observations at Cambridge. None of the Australian research results using the spaced interferometry technique appeared in publications, and the invention of the solar grating array in 1950 made further use of the method redundant.

Evaluation of a novel compact shearography system with DOE configuration

The most common optical configuration used to produce the lateral shifted images, in a Shearography system, is the Modified Michelson interferometer, because of its simple configuration. Tests carried out in recent years have shown that the modified interferometer of Michelson is a device that presents good results in a laboratory environment, but still presents difficulties in the field. These difficulties were the main motivation for the development of a more robust system, able to operate in unstable environments. This paper presents a new shearography configuration based on Diffractive Optical Element (DOE). Different from the diffractive common-path setups found in literature, in the proposed configuration, the DOE is positioned between the image sensor and the objective lens and mounted on a flexible holder, which has an important function to promote the system's robustness. Another advantage of the proposed system is in respect to phase shifting, since it is insensitive to wavelength variations. The lateral movement of the DOE produces a phase shifting in the shearography system. Since the pitch of the diffractive grating used is about 60 times greater than the wavelength of a green laser, the DOE configuration becomes much more robust to external influences compared to the Michelson Interferometer configuration. This work also presents an evaluation of the proposed shearography system designed, and some comparative results regarding a classical shearography system.

Michelson Interferometer Thermo-Optic Switch on SOI With a 50-µW Power Consumption

We demonstrate photonic ultra-efficient thermo-optic switches on a 220-nm silicon-on-insulator platform. We used several approaches to increase the tuning efficiency of the switches. We used folded waveguides in a Michelson interferometer configuration to increase the optical interaction length of the light with the heated region, and used a suspended structure to improve thermal isolation. An ultra-low switching power of 50 $\mu \text{W}$ is realized with an extinction ratio of over 26 dB for the transverse electric mode at 1550 nm. The 10%–90% response time of the switch is 1.28 ms, including a 780 $\mu \text{s}$ rise time and a 500 $\mu \text{s}$ fall time. Compared with the best thermo-optic switch in the literature, our device shows approximately an order of magnitude reduction in power consumption.

Spatial measurement of ultrashort light pulses using two photon absorption in a colliding geometry

In this work the spatial measurement of ultrashort light pulses through two photon absorption (TPA) is analyzed. The method is based on a Michelson interferometer configuration in a colliding geometry where the light pulses meet each other in a cell with Rhodamine B in ethanol, which emits a fluorescence that can be detected with a standard digital camera. The analysis of the experimental spatial trace as well as the theoretical derivation show that the Full Width at Half Maximum (FWHM) measured is FWHMmeasured=FWHMsingle_pulse/2 instead of the general value 2 FWHM single_pulse of temporal or spatial collinear approaches. The influence of the pulse chirp on the measurement and the error caused by the camera misalignment are analyzed.

Large angular range carousel interferometer for spectroscopic applications

A six-mirrored carousel interferometer has been designed. The technique utilizes Michelson interferometer configuration which consists of six mirrors and a pair of compensating glass plates. Optical path difference generated due to rotation is used to measure angle and axis of rotation. The resultant at the output port of the interferometer is optimized to reduce nonlinearity for different ranges of rotations ±5°, ±10°, ±15°, and ±20°. When glass plates are introduced maximum nonlinearity for these ranges are 5.40 × 10−7, 8.53 × 10−6, 4.18 × 10−5, and 1.26 × 10−4 respectively. The reported interferometer has applications in high resolution Fourier transform spectroscopy and commercially available gas analysis systems apart from other metrological applications.

Photonic Integrated Multichannel WDM Modulators for Data Read-Out Units

This study presents the recently developed monolithic photonic-integrated circuits that provide efficient amplitude modulation for wavelength division multiplexed optical channels. The circuits were designed for application as a read-out unit in a high-energy physics experiment, and are sufficiently general to be applied in various types of high-speed photonic transmitters. They were constructed using basic building blocks provided in an indium phosphide-based generic integration technology process and fabricated in a multi-project wafer run. Two variants of the circuits, utilizing modulators in Mach-Zehnder and Michelson interferometer configuration, are discussed. A modulation bandwidth of 18.6 GHz was measured and error-free transmission of a 10-Gb/s signal through 85 km of optical fiber was achieved.

Fiber optic magnetic field sensor based on the TbDyFe rod

We present, and experimentally demonstrate, a fiber optic magnetic field sensor for the measurement of a weak alternating magnetic field, based on a TbDyFe rod. The fiber optic magnetic field sensor is constructed in a Michelson interferometer configuration, and the phase-generated carrier demodulation is used to obtain the time-varying phase shift induced by the applied magnetic field. A high sensitivity of up to 3.6 × 10–2 V μT − 1 (rms) with a resolution of 23 pT/√Hz (rms) at 50 Hz is achieved. Experimental results show that the sensor exhibits excellent linearity and reversibility.

Multiple One-Dimensional Search (MODS) algorithm for fast optimization of laser–matter interaction by phase-only fs-laser pulse shaping

In this work, we have developed and implemented a powerful search strategy for optimization of nonlinear optical effects by means of femtosecond pulse shaping, based on topological concepts derived from quantum control theory. Our algorithm [Multiple One-Dimensional Search (MODS)] is based on deterministic optimization of a single solution rather than pseudo-random optimization of entire populations as done by commonly used evolutionary algorithms. We have tested MODS against a genetic algorithm in a nontrivial problem consisting in optimizing the Kerr gating signal (self-interaction) of a shaped laser pulse in a detuned Michelson interferometer configuration. The obtained results show that our search method (MODS) strongly outperforms the genetic algorithm in terms of both convergence speed and quality of the solution. These findings demonstrate the applicability of concepts of quantum control theory to nonlinear laser–matter interaction problems, even in the presence of significant experimental noise.

Fast processing of optical fringe movement in displacement sensors without using an ADC

An interferometer based optical sensor for displacement measurement is reported. This method requires quite simple signal processing as well as least electronic components. Referring to this technique, two photodiodes spatially shifted by 90 degrees were used. The output of photodiodes was converted into rectangular signals which were extracted in LabVIEW using the data acquisition card without using an analog to digital converters (ADC). We have also processed the signals in C++ after acquiring via parallel port. A Michelson interferometer configuration was used to produce linear fringes for the detection of displacements. The displacement less than 100 nm could be measured using this technique.

Comparison of the coherence properties of superradiance and laser emission in semiconductor structures

The coherence properties of a transient electron – hole state developing during superradiance emission in semiconductor laser structures have been studied experimentally using a Michelson interferometer and Young's classic double-slit configuration. The results demonstrate that, in the lasers studied, the first-order correlation function, which quantifies spatial coherence, approaches unity for superradiant emission and is 0.2 – 0.5 for laser emission. The supercoherence is due to long-range ordering upon the superradiant phase transition.

Fibre optic long period grating-based humidity sensor probe using a Michelson interferometric arrangement

Long period gratings (LPG)-based sensors are widely used due to their high sensitivity to a range of suitable measurands. However, a typical configuration involving a single grating-based LPG sensor system frequently has the disadvantage of the probe being used in transmission mode. Further, the broad bandwidth of the attenuation bands formed by the propagation mode coupling between the core and the cladding modes constitutes a difficulty when the device is used as a conventional sensor probe. To overcome these limitations, a Michelson interferometer-type sensor configuration has been developed, using a LPG grating pair formed by coating a mirror at the distal end of the LPG. This sensor configuration is more convenient to use and is able to overcome the limitations of the single LPG sensor due to the shifts in the attenuation bands being more easily detectable. As part of work to develop an optimum configuration for the probe, a series of tests has been carried out to determine the most suitable distance between the LPG and the mirror coating for a typical grating (LPG) of period 250μm. The sensor thus developed was then calibrated for use for temperature and refractive index measurement. In this paper, the design of a LPG coated with polyvinyl alcohol (PVA) as a relative humidity (RH) sensor and used in the Michelson interferometer configuration is reported. PVA, which swells with the increase of RH in its surroundings, causes a change in the refractive index of the coated polymer layer which was observed by tracking the response of the resonance loss band of the LPG to varying RH levels. The distal end of the fibre containing the LPG has been coated with a silver mirror in order to track the shift of the resonance loss band in reflection and to achieve a high resolution. The sensor was evaluated by being subjected to humidity changes over a RH range from 20% to 85% and an excellent detection performance was obtained while retaining the sensitivity of the PVA coated sensor.

Interferometric measurement of laser heating in praseodymium-doped YAG crystal

Temperature measurement is required for many applications but can be difficult in some cases. Laser heating or cooling studies demand accurate measurements of temperature changes. A Michelson interferometer configuration has been used to investigate laser heating in solids. An analytical formula was derived to estimate the temperature change from the fringe count by taking into account the temperature dependence of the sample length and refractive index. When 115 mW of a focused Ar+ laser beam (488 nm) passes through a Pr(3+)-doped YAG sample, its temperature increased by 11.7±1.0 K along the beam path due to nonradiative relaxation. The power dependence of the fringe count/movement was recorded. The temperature change was estimated by the interferometric method and is in agreement with that measured by a thermocouple.

Phase sensitive absolute amplitude detection of surface vibrations using homodyne interferometry without active stabilization

A detection scheme for obtaining phase and absolute amplitude information of surface vibrations on microacoustic components using homodyne laser interferometry is described. The scheme does not require active stabilization of the optical path length of the interferometer. The detection setup is realized in a homodyne Michelson interferometer configuration, and selected measurements on a 374 MHz surface acoustic wave fan-shaped filter and two different piezoelectrically actuated micromechanical resonators are presented to demonstrate the performance of the instrument. With the current detection electronics, the interferometer is capable of detecting out-of-plane surface vibrations up to 2 GHz with a lateral resolution of better than 1 μm and with a minimum detectable vibration amplitude of ∼1 pm.