Showing papers on "Mach–Zehnder interferometer published in 1987"
TL;DR: An optical filter that displays the time-dependent features of a scene using a modified liquid-crystal television used as a spatial light phase modulator in the interferometer to detect time- dependent features of an image viewed by a video camera.
Abstract: We demonstrate an optical filter that displays the time-dependent features of a scene. The heart of the device is an interferometer that is sensitive not to the difference between two optical paths lengths but to changes in the path-length difference. The interferometer arms share a phase-conjugating mirror. The phase conjugator ensures that, at steady state, the output of the interferometer is dark. The response of the interferometer to a step differential change in the optical lengths is a decaying exponential having a time constant governed by the time response of the phase conjugator. The interferometer may be used to monitor time- and space-dependent optical phase changes that are due, for example, to transparent fluid motion. With a modified liquid-crystal television used as a spatial light phase modulator in the interferometer, we detect time-dependent features of an image viewed by a video camera.
121 citations
TL;DR: In a quantum mechanical two-slit experiment, a single photon can be observed simultaneously as particle (measuring the path) and as wave if the path and the interference pattern are measured in the sense of unsharp observables as discussed by the authors.
Abstract: In a quantum mechanical two-slit experiment one can observe a single photon simultaneously as particle (measuring the path) and as wave (measuring the interference pattern) if the path and the interference pattern are measured in the sense of unsharp observables. These theoretical predictions are confirmed experimentally by a photon split-beam experiment using a modified Mach—Zehnder interferometer.
120 citations
TL;DR: The present interferometer is different from a shearing type in that the phase distribution of an object beam is directly analyzed from the acquired intensity variations obtained by a 2-D detector such as a TV camera.
Abstract: A new type of phase shifting interferometer with a common-path arrangement using a polarization technique is proposed and discussed. In the interferometer, the dc (specular) component of an object beam is separated in the Fourier transform plane and used as a reference beam for its ac component. The phase of the dc component used as the reference beam is shifted by using a polarization technique for phase shifting interferometry. The present interferometer is different from a shearing type in that the phase distribution of an object beam is directly analyzed from the acquired intensity variations obtained by a 2-D detector such as a TV camera. Some experiments were conducted to verify the validity of the present phase shifting interferometer. They showed that high stability of the phase measurements is achieved up to λ/200 with an accuracy of λ/40 for wavelength λ light. The interferometer is suitable for obtaining 2-D phase information about the surface structure of small objects.
52 citations
TL;DR: The implementation of a new type of phase-shifting, self-referencing interferometer that simultaneously achieves the phase shift and separation of heams with a stationary diffraction grating is described.
Abstract: The implementation of a new type of phase-shifting, self-referencing interferometer that simultaneously achieves the phase shift and separation of heams with a stationary diffraction grating is described. The capabilities of stroboscopic interferometry are demonstrated with results from an experiment in which the rapidly varying surface deformations of a sonically activated pellicle mirror are measured in a time-sliced fashion at 50-microsec intervals.
47 citations
TL;DR: In this article, the authors constructed a figure of merit for broadband electrooptic modulators which compares bandwidth with launched generator voltage standardized to a common wavelength, and showed that a lumped-element III-V semiconductor device performance may be no more than a factor of two below that of typical (i.e., LiNbO 3 ) traveling wave devices and are probably easier to implement-especially in an integrated format.
Abstract: A figure of merit is constructed for broad-band electrooptic modulators which compares bandwidth with launched generator voltage standardized to a common wavelength. Comparison of various published results in terms of this figure shows that a lumped-element III-V semiconductor device performance may be no more than a factor of two below that of typical (i.e., LiNbO 3 ) traveling wave devices and are probably easier to implement-especially in an integrated format. Accurate modeling, which incorporates all transit time and velocity match effects, is described and found to agree well with experimental results. Experimental GaAs/GaAlAs modulators have been made, using a Mach-Zehnder interferometer configuration. At a wavelength of 1.15 μm and with unterminated drive a bandwidth of 6.5 GHz was obtained with V pi of 17.3 V. A shorter (34.6-v) device was ∼ 1.25-dB down at 8.4 GHz. The corresponding figures of merit are close to the maximum expected for the configurations used.
41 citations
TL;DR: In this article, a push-pull fiber-optic hydrophone is analyzed theoretically by closed-form approximations, where 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.
Abstract: 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.
38 citations
Patent•
10 Mar 1987
TL;DR: An optical fiber Michelson interferometer has mirrors of highly reflective coatings deposited on the ends of the fibres forming the free arms of the interferometers as mentioned in this paper, and is operated by a frequency swept laser.
Abstract: An optical fibre Michelson interferometer has mirrors of highly reflective coatings deposited on the ends of the fibres forming the free arms of the interferometer. The interferometer preferably comprises single mode fibres, and is operated by a frequency swept laser. The interferometer has applications in the optical fibre interferometer sensing field.
28 citations
TL;DR: In this article, the nonlinear refractive index of optical fibres from the phase shift resulting from crossphase modulation between a probe signal and a pulsed pump was computed with a Mach-Zehnder interferometer.
Abstract: We have computed the nonlinear refractive index of optical fibres from the phase shift resulting from crossphase modulation between a probe signal and a pulsed pump. This phase shift is obtained with a Mach-Zehnder interferometer. Values of 0.92 × 10-13esu for silica and 0.80 × 1013esu for fluorozirconate glasses have been measured.
28 citations
TL;DR: In this paper, an all-optical switching device on a nonlinear Mach-Zehnder waveguide interferometer is proposed and analyzed, where the nonlinear medium is modeled as a two-level system to take saturation and attenuation effects into account.
Abstract: We propose and analyze an all‐optical switching device on a nonlinear Mach–Zehnder waveguide interferometer. The nonlinear medium is modeled as a two‐level system to take saturation and attenuation effects into account.
25 citations
Patent•
03 Nov 1987TL;DR: In this article, an interferometer consisting of two interferometers is used to perform length measurement or angle measurement as well as index of refraction measurement simultaneously, using an evacuable arrangement.
Abstract: The invention is directed to an interferometer which includes two interferometer systems and with which length measurement or angle measurement as well as index of refraction measurement can be conducted simultaneously. For this purpose, at least one component beam from the measuring arm of the one interferometer system and a component beam from a comparison arm of the other interferometer system are directed through an evacuable arrangement.
24 citations
TL;DR: In this paper, a squeezed-state enhanced interferometer was proposed to demonstrate the effect of coherent light having two frequency components ν0 + νs and ν 0 − ξs on the readout signal at the detector.
Abstract: Here an experiment is proposed to demonstrate squeezed-state enhanced interferometry. An interferometer employing differenced detection, in which the photodetectors have less than a unit quantum efficiency, is analyzed. In order to avoid low-frequency noise, a readout signal at frequency 2νs is generated at the detector by injecting coherent light having two frequency components ν0 + νs and ν0 − νs into one input port of the interferometer. In order to realize a significant sensitivity enhancement, squeezed light fed into the other input port must be squeezed at frequencies ν0 ± νs and ν0 + 3νs.
CNET1
TL;DR: In this article, singlemode fibres were inserted in one arm of a classical Mach-Zehnder interferometer, illuminated with a light source having a broad spectral width.
Abstract: Single-mode fibres were inserted in one arm of a classical Mach-Zehnder interferometer, illuminated with a light source having a broad spectral width. A simple numerical Fourier transform method, applied to a single interferogram, leads to the variations in neff(λ) over a broad λ-range. The chromatic dispersion is then derived via numerical differentiation.
TL;DR: In this paper, two modifications of the integrated optic Mach-Zehnder interferometer device are proposed which could be used to measure large electric fields, for example, in high voltage lines in utility substations.
Abstract: Two modifications of the integrated optic Mach-Zehnder interferometer device are proposed which could be used to measure large electric fields, for example, in high voltage lines in utility substations. These new devices consist of an asymmetric slab and a strip-loaded diffused waveguide. They would merely be immersed in the field to be measured. Interrogation would be by optical fiber. The theory of operation of these devices is developed and examples are worked using the optical constants of possible materials.
TL;DR: In this paper, a high-sensitivity differential interferometer was developed to detect small density fluctuations over an optical path length of the order of the boundary layer thickness near transition.
Abstract: A high-sensitivity differential interferometer has been developed to detect small density fluctuations over an optical path length of the order of the boundary layer thickness near transition. Two experimental configurations have been used to evaluate the performance of the interferometer: an open shear-layer configuration and a wind-tunnel turbulent spot configuration. In each experiment small temperature fluctuations were introduced as the signal source. Simultaneous cold-wire measurements have been compared with the interferometer data. The comparison shows that the interferometer is sensitive to very weak phase variations of the order of 0.001 of the laser wavelength.
TL;DR: In this paper, an optical frequency shifter was constructed which uses travelling acoustic flexure waves induced on a single linearly birefringent monomode fiber to produce mode coupling between the two orthogonal polarisation eigenmodes.
Abstract: An optical frequency shifter has been constructed which uses travelling acoustic flexure waves induced on a single linearly birefringent monomode fibre to produce mode coupling between the two orthogonal polarisation eigenmodes. The output of the frequency shifter is examined using a heterodyne interferometer. The measured efficiency was ?2% at a shift frequency of 491 kHz.
28 Apr 1987
TL;DR: In this article, the properties of piezoactive plastics are reviewed as well as the fiber-optic electric field sensors studied so far, and a particular configuration consisting of a concentric piezo active jacket on the glass fiber is discussed in detail and the frequency response of this sensor is projected over a wide range of frequencies.
Abstract: The properties of piezoactive plastics are reviewed as well as the fiber-optic electric field sensors studied so far. A particular configuration consisting of a concentric piezoactive jacket on the glass fiber is discussed in detail and the frequency response of this sensor is projected over a wide range of frequencies. The present design has the practical advantages of leading to a compact lightweight sensor; longer fiber lengths may be used to increase sensitivity. It is predicted that, at low frequencies, a fiber-optic antenna using a 1-km length of fiber would be capable of detecting a minimum electric field of 43 microV/m assuming a minimum phase sensitivity of 10 to the -6th radians for the optical Mach-Zehnder interferometer.
TL;DR: In this paper, the effects of electrical loss on the bandwidth and drive requirements of traveling-wave LiNbO 3 couplers and interferometric devices are discussed, and it is shown that electrical loss in the transmission line is more detrimental to a coupler than to an interferometer.
Abstract: It is shown that a coupler and interferometer may be considered two extremes of a generalized two-guide coupler device in which electrode length is less than a coupling length For electrode lengths less than half of a coupling length, the generalized device looks more like an interferometer than a coupler The impedance and electrical loss of asymmetric-stripe and coplanar-waveguide transmission lines on LiNbO 3 for thick as well as thin electrodes are then presented The effects of the electrical loss on the bandwidth and drive requirements of traveling-wave LiNbO 3 couplers and interferometric devices are discussed, and it is shown that electrical loss in the transmission line is more detrimental to a coupler than to an interferometer These results are then used to compare the drive power requirements of coupler and interferometric devices, and it is shown that for the same bandwidth and same optical guide dimensions, an interferometric device with a coplanar transmission line can require a lower drive power than a coupler with an asymmetric-stripe line
TL;DR: In this article, the authors measured density fluctuations in magnetically confined plasmas from the phase scintillations impressed onto a 10.6μm wavelength laser beam probe, using a Mach-Zender interferometer operating in the optical near field.
Abstract: Density fluctuations in magnetically confined plasmas have been measured from the phase scintillations impressed onto a 10.6‐μm wavelength laser beam probe, using a Mach–Zender interferometer operating in the optical near field. By careful design, the effects of vibration and air‐borne sound waves, which limit the instrument’s sensitivity, have been reduced to a level such that the minimum detectable signal is 10−6 rad in the frequency range 10 kHz–1 MHz, corresponding to a plasma density fluctuation level (δN/N) of 10−4.
TL;DR: In this paper, a thermal modulator was proposed to maintain the interferometer in its most sensitive (quadrature) condition, and thus represents a potential replacement for the comparatively bulky piezoelectric transducers (PZT) customarily used.
Abstract: This paper describes a new device which utilizes the thermal sensitivity of optical fibers to modulate the phase of the light in an interferometric sensor. The purpose of the optical-fiber thermal modulator is to maintain the interferometer in its most sensitive (quadrature) condition, and it thus represents a potential replacement for the comparatively bulky piezoelectric transducers (PZT) customarily used. Shorter lengths of fiber and considerably lower voltages than are required for the piezoelectric devices produce phase shifts of many wavelengths in the optical-fiber thermal modulator.
TL;DR: An equilateral hyperbolic zone plate has been recorded by coherent superimposition of two cylindrical waves with coplanar foci, used to align quickly and easily a Mach-Zehnder interferometer.
Abstract: An equilateral hyperbolic zone plate has been recorded by coherent superimposition of two cylindrical waves with coplanar foci. This zone plate has been used to align quickly and easily a Mach-Zehnder interferometer.
TL;DR: In this article, an interferometric method to determine the gas density in a gas-droplet mixture using a laser Mach-Zehnder interferometer in the phase quadrature mode is described.
Abstract: A description is given of an interferometric method to determine the gas density in a gas-droplet mixture. The method uses a laser Mach-Zehnder interferometer in the phase quadrature mode. It is shown that a direct, quantitative and unambiguous determination of gas density changes is possible in a medium that contains light scattering particles. Examples are given of the application of the interferometer to expanding flows with condensation and to shock wave propagation in a fog, illustrating the potential of the method for large and fast density variations.
01 Jan 1987
TL;DR: In this paper, the Michelson, Mach Zehnder and Fabry-Perot interferometers are compared with their fiber optic equivalents, together with signal processing techniques which enable these devices to operate over a large dynamic range with constant sensitivity to induced optical phase changes.
Abstract: In this chapter we review the Michelson, Mach Zehnder and Fabry-Perot interferometers and introduce their fibre optic equivalents, together with signal processing techniques which enable these devices to operate over a large dynamic range with constant sensitivity to induced optical phase changes. The lower resolution polarimetric (differential) interferometer and associated signal processing to enable it to be operated remotely is also considered. The application of these novel fibre optic interferometers to a variety of measurements such as temperature, magnetic field, displacement and sound waves is described.
TL;DR: In this paper, a simple beam splitter arrangement is used to divide a single ultrashort optical pulse into four beams of accurately known jitter-free delay, and the 50-ps ruby laser beams are used in a Mach-Zehnder interferometer to produce four interferograms in one shot of the CO2-laser-irradiated plasma at an interframe delay of 95 ps.
Abstract: A simple beam splitter arrangement is used to divide a single ultrashort optical pulse into four beams of accurately known jitter-free delay. The 50-ps ruby laser beams are used in a Mach-Zehnder interferometer to produce four interferograms in one shot of the CO2-laser-irradiated plasma at an interframe delay of 95 ps. Fringe straightness of <1/10 wave error is attained in all four frames by overlapping reference and scene beams precisely on the film while relaxing the constraint of the high spatial coherence necessary in shearing and folding shear interferometry. Such high fringe quality is required to record properly the observed fractional fringe shifts in a plasma of electron density up to ne = 5 × 1018 cm−3. The four-frame interferogram, recorded on Polaroid-type 667 film, is available immediately after the shot is taken. Neither a streak camera for recording timing sequences nor wavelength filters for rejection of plasma light was required. Simple rearrangement of optical components allows framing rates of 10.5 or 21.0 GHz.
TL;DR: In this paper, an all-optical amplifier for AM signals is proposed, which is an integrated Mach-Zehnder interferometer where both arms are pumped with light from the incoming signal, amplified in a semiconductor laser amplifier.
Abstract: We propose an all-optical amplifier for AM signals which, in principle, is an integrated Mach-Zehnder interferometer where both arms are pumped with light from the incoming signal, amplified in a semiconductor laser amplifier. Thus the pump is the time integrated phase and amplitude average of the signal. In one of the arms a part of the nonamplified signal is injected, which modulates the optical path length in that arm with the optical Kerr effect. After the final junction between the arms, the outgoing light is proved to carry a part of the amplitude of the pump and the modulation of the signal.
01 Jan 1987
TL;DR: In this paper, a traveling-wave Mach-Zehnder modulator using the electro-optic effect of GaAs and operating at a wavelength of 0.78 to 0.88 micron has been investigated for the first time.
Abstract: A GaAs modulator operating at 0.78 to 0.88 micron wavelength has the potential to be integrated with a GaAs/GaAlAs laser diode for an integrated fiber-optic transmitter. A travelling-wave Mach-Zehnder modulator using the electro-optic effect of GaAs and operating at a wavelength of 0.82 microns has been investigated for the first time. A four layer Strip-loaded ridge optical waveguide has been analyzed using the effective index method and single mode waveguides have been designed. The electro-optic effect of GaAs has also been analyzed and a modulator using the geometry producing the maximum phase shift has been designed. A coplanar transmission line structure is used in an effort to tap the potentially higher bandwidth of travelling-wave electrodes. The modulator bandwidth has been calculated at 11.95 GHz with a required drive power of 2.335 Watts for full intensity modulation. Finally, some preliminary experiments were performed to characterize a fabrication process for the modulator.
Patent•
16 Sep 1987
TL;DR: In this article, an electrically controllable variable optical power ratio branching element is constituted by a tandem arrangement of two 4-port fused fibre couplers in Mach Zehnder Interferometer configuration formed from a single pair of fibres.
Abstract: An electrically controllable variable optical power ratio single mode fibre branching element is constituted by a tandem arrangement of two 4-port fused fibre couplers (20, 21) in Mach Zehnder Interferometer configuration formed from a single pair of fibres (3, 4) which are mounted on a silica substrate (30). Between the two couplers the fibres extend side by side in close proximity through mechanical decoupling means (33, 34) with one of the fibres being cemented in the intervening region to an electrostrictive transducer 38. Optionally the other fibre is similarly cemented to a second transducer.
Patent•
04 Aug 1987TL;DR: In this article, an acousto-optic device is inserted downstream of the device for splitting the beam emitted by the source into the two beams sent along the two interferometer branches, or it can also act as the beam splitter.
Abstract: The interferometer makes use of an acousto-optic device to perform a frequency shift of the beam sent along one of the interferometer branches, so as to allow the determination of the state of polarization by heterodyne radiofrequency detection. The acousto-optic device can be inserted downstream of the device for splitting the beam emitted by the source into the two beams sent along the two interferometer branches, or it can also act as the beam splitter.
01 Jan 1987
TL;DR: In this article, the analysis and design of a GaAlAs Mach-Zehnder electrooptic modulator operating at 820 nm was presented, achieving 3dB bandwidth-length product of 11.95 GHz cm.
Abstract: The analysis and design of a GaAlAs Mach-Zehnder electrooptic modulator operating at 820 nm is presented. Optical modulation is achieved through coplanar 50-ohm traveling-wave microwave electrodes with a resulting 3-dB bandwidth-length product of 11.95 GHz cm.
TL;DR: It is shown that the biprism used to combine identical spatially incoherent wavefronts that have been split by an amplitude splitting interferometer can exhibit extended source fringe formation capability greatly exceeding that of the Mach-Zehnder interferometers.
Abstract: A biprism is used to combine identical spatially incoherent wavefronts that have been split by an amplitude splitting interferometer such as the Mach-Zehnder. The performance of this composite interferometer is evaluated by tracing the chief ray through parallel optical systems using Snell's law and trigonometry. Fringes formed in spatially incoherent light with this optical system are compared with those formed using the Mach-Zehnder and grating interferometers. It is shown that the combination can exhibit extended source fringe formation capability greatly exceeding that of the Mach-Zehnder interferometer.
01 Jun 1987
TL;DR: In this article, a singlemode optical-fibre switch which is electrically activated has been fabricated by forming two couplers in series on a pair of single-mode optical fibres to provide a compact Mach-Zehnder interferometer.
Abstract: A single-mode optical-fibre switch which is electrically activated has been fabricated. This device is achieved by forming two couplers in series on a pair of single-mode optical fibres to provide a compact Mach-Zehnder interferometer (MZI). Power switching in the output arms is achieved by introducing a phase shift or path difference in the MZI by various means. The application of the device as a wavelength-selective switch is also considered.