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Showing papers on "Mach–Zehnder interferometer published in 1991"


Journal Article
TL;DR: In this paper, periodic phase changes in the 10−6 -rad region were induced and detected in a single-mode all-fiber Mach-Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10−4 Hz.
Abstract: Periodic phase changes in the 10(-6) -rad region have been induced and detected in a single-mode all-fiber Mach- Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10(4) Hz.

191 citations


Journal ArticleDOI
TL;DR: In this article, an electro-optic (EO) polymer-based integrated optic Mach-Zehnder modulator with a measured frequency response up to 20 GHz was reported.
Abstract: An electro‐optic (EO) polymer‐based integrated optic Mach–Zehnder modulator with a measured frequency response up to 20 GHz is reported. The device was fabricated with an EO polymer supplied by Akzo Research, bv, and utilized 50 Ω microstrip drive electrodes. A half‐wave voltage of Vπ=9 V and a modulation depth of 90% were measured at 2 kHz. Modulation was observed out to 8.0 GHz using direct detection and out to 20 GHz using a frequency mixing technique, limited by the drive and receiver electronics.

157 citations


Journal ArticleDOI
TL;DR: In this paper, the free-carrier-induced change in the refractive index of silicon has been used to characterize the waveguide operation at the wavelength of 1.3 μm.
Abstract: Silicon Mach–Zehnder waveguide modulators have been fabricated and operation characterized at the wavelength of 1.3 μm. Device operation is based on the free‐carrier‐induced change in the refractive index of silicon. Modulation depths of −4.9 dB and response times τresponse<50 ns have been achieved at λ=1.3 μm for an injected carrier density of 6.5×1017 cm−3.

112 citations


Journal ArticleDOI
G. V. Treyz1
TL;DR: In this article, the switching mechanism is based on the thermally induced variation of the refractive index of crystalline silicon, which has been demonstrated at λ = 1.3 μm.
Abstract: Mach-Zehnder waveguide interferometers have been fabricated in silicon and operation has been demonstrated at λ = 1.3 μm. The switching mechanism is based on the thermally induced variation of the refractive index of crystalline silicon. Modulation depths of 40% were obtained for switching powers of 30 mW and switching times of 50 μs.

108 citations


Journal Article
TL;DR: In this article, the authors proposed a new technique, the squeezed-state technique, that allows one to decrease the photon-counting error while increasing the radiation pressure error, or vice versa.
Abstract: The interferometers now being developed to detect gravitational waves work by measuring the relative positions of widely separated masses. Two fundamental sources of quantum-mechanical noise determine the sensitivity of such an interferometer: (i) fluctuations in number of output photons (photon-counting error) and (ii) fluctuations in radiation pressure on the masses (radiation-pressure error). Because of the low power of available continuous-wave lasers, the sensitivity of currently planned interferometers will be limited by photon-counting error. This paper presents an analysis of the two types of quantum-mechanical noise, and it proposes a new technique---the "squeezed-state" technique---that allows one to decrease the photon-counting error while increasing the radiation-pressure error, or vice versa. The key requirement of the squeezed-state technique is that the state of the light entering the interferometer's normally unused input port must be not the vacuum, as in a standard interferometer, but rather a "squeezed state"---a state whose uncertainties in the two quadrature phases are unequal. Squeezed states can be generated by a variety of nonlinear optical processes, including degenerate parametric amplification.

95 citations


Journal ArticleDOI
TL;DR: In this paper, a guided-wave Mach-Zehnder interferometer structure, based on the use of a four-port hybrid optical coupler consisting of symmetric and nonsymmetric y junctions, is proposed for wavelength division multiplexing application.
Abstract: A guided-wave Mach-Zehnder interferometer structure, based on the use of a four-port hybrid optical coupler consisting of symmetric and nonsymmetric y junctions, is proposed for wavelength-division multiplexing application. This structure provides less sensitivity to fabrication parameters and optical polarization, and can also be applied to a wide-wavelength spacing operation. Interferometers for wavelength splitting in the 1.3- and 1.55- mu m windows were designed and fabricated into a glass substrate with a dry silver ion exchange process. The measured crosstalk was -30 dB with nonpolarized light. >

52 citations


Journal ArticleDOI
B. K. Nayar1, N. Finlayson1, Nick Doran1, Steven T. Davey1, D.L. Williams1, John W. Arkwright1 
TL;DR: All-optical switching is demonstrated in a 200-m-long fiber nonlinear Mach-Zehnder interferometer and stable operation is obtained by using a twin-core fiber.
Abstract: All-optical switching is demonstrated in a 200-m-long fiber nonlinear Mach–Zehnder interferometer. The only stabilization mechanism used is passive enclosure of the interferometer. Stable operation is obtained by using a twin-core fiber. The experiment demonstrates the feasibility of use of fiber nonlinear Mach–Zehnder interferometers for ultrafast switching and pipeline logic.

46 citations


Journal ArticleDOI
TL;DR: In this paper, hybrid mode and quasi-TEM analyses are carried out for coplanar waveguide traveling-wave electrodes applicable to z-cut Ti:LiNbO3 optical modulators.
Abstract: Hybrid-mode and quasi-TEM analyses are carried out for coplanar waveguide traveling-wave electrodes applicable to z-cut Ti:LiNbO3 optical modulators. The analyses are based on the spectral-domain approach. The microwave effective index and the characteristic impedance are clarified, together with the microwave conductor loss. These are incorporated to accurately predict the modulator characteristics. It is shown that these characteristics can be greatly improved by employing a thicker buffer layer. High-speed and low-driving-power Ti:LiNbO/sub 3/ optical modulators are realized at 1.52 mu m wavelength. Agreement between the calculated and measured results is good. >

46 citations


Journal ArticleDOI
TL;DR: In this article, the fabrication of directional couplers (2×2 switches) and Mach-Zehnder interferometers (intensity modulators) using electro-optic polymeric multilayer structures is described.
Abstract: In this paper the fabrication of directional couplers (2×2 switches) and Mach–Zehnder interferometers (intensity modulators) using electro‐optic polymeric multilayer structures, is described. Results show attractively low switching voltages (<10 V for 1.4 cm long devices) and very good on‐off ratios (17 dB) for the directional couplers. In the case of the Mach–Zehnder interferometers, Vπ‐values of 4.5 V have been obtained, also for 1.4 cm long devices.

36 citations


Journal ArticleDOI
TL;DR: In this paper, two diode-pumped Nd:YAG lasers are combined with their polarization vectors at 90° to each other to create a depolarized source suitable for propagation over long lengths of ordinary, low-birefringence single-mode fiber without a change in the polarization state.
Abstract: Two diode-pumped Nd:YAG lasers are combined with their polarization vectors at 90° to each other to create a depolarized source suitable for propagation over long lengths of ordinary, low-birefringence single-mode fiber without a change in the polarization state. The source is demonstrated with an integrated-optical Mach–Zehnder interferometer and provides a constant −3-dB intensity input to the required linear input polarization state.

34 citations


Journal ArticleDOI
TL;DR: In this article, a phase modulation recovery scheme applied to an optical Michelson interferometer using polarization encoding is described, where the low-frequency components of the phase shift between the two interfering beams are locked at zero (within limits set only by shot noise).
Abstract: The measurement of nanometre displacements with picometre resolution has been made possible by a phase-modulation recovery scheme applied to an optical Michelson interferometer using polarization encoding. In contrast to conventional schemes, phase modulation is carried out before the interferometer optics. In this way, the low-frequency components of the phase shift between the two interfering beams are locked at zero (within limits set only by shot noise) before beam splitting by a feedback loop driving the modulator. An interferometer prototype, illuminated by a beam thus modulated, was constructed and coupled to an X-ray interferometer to compare the optical and X-ray interferometric measurement values of sub-nanometre displacements. A resolution better than 1 pm over a 100 Hz bandwidth was obtained.

Journal ArticleDOI
TL;DR: In this article, a single-probe heterodyne laser interferometer has been modified to a dualprobe modality by utilizing the reference beam as a second probe and the two probing beams display the same sensitivity, independent of the difference in reflectivities at two points of detection on the specimen.
Abstract: A single‐probe heterodyne laser interferometer has been modified to a dual‐probe modality by utilizing the reference beam as a second probe. It is shown that the two probing beams display the same sensitivity, independent of the difference in reflectivities at the two points of detection on the specimen. The dual‐probe interferometer allows measurements of the same surface wave signal at two points. The instrument is particularly suited for the measurement of the speed and attenuation of surface waves. The interferometer has been employed to determine phase velocities and attenuation coefficients for surface wave propagation over an aluminum plate with increasing degrees of surface roughness.

Journal ArticleDOI
TL;DR: The fabrication of a new design of fused single-mode-fiber wavelength-flattened 2 x 2 couplers is reported, which shows good coupling-ratio uniformity and low excess loss.
Abstract: The fabrication of a new design of fused single-mode-fiber wavelength-flattened 2 × 2 couplers is reported. The device consists of a slightly unbalanced all-fiber Mach–Zehnder interferometer made with identical single-mode fibers; it is compact (≈2 cm) and shows good coupling-ratio uniformity (50 ± 2.5% over 300 nm) with low excess loss (<0.1 dB).

Journal ArticleDOI
TL;DR: In this article, the gradient of refractive index around a crystal growing from a solution was quickly obtained by a 16 bit personal computer using electronic measurement of fringes of Mach-Zehnder interferometer.

Journal ArticleDOI
TL;DR: In this article, a 2*2 asymmetric Mach-Zehnder interferometric modulator is fabricated on Ti:LiNbO/sub 3/ waveguide and tested at microwave frequency.
Abstract: A novel 2*2 asymmetric Mach-Zehnder interferometric modulator is fabricated on Ti:LiNbO/sub 3/ waveguide and tested at microwave frequency. Band-limited operation was realized by using a traveling-wave periodic polarity reversed structure with the asymmetric strip line as the modulator electrode instead of the conventional coplanar waveguide. For a modulator with a three-section polarity reversed electrode, a 3-dB bandwidth of 7 GHz was obtained experimentally from 9 to 16 GHz centered at 12 GHz. >

Patent
Ari Tervonen1
14 Oct 1991
TL;DR: In this paper, a Mach-Zehnder interferometer comprising a symmetrical optical y-junction for dividing an input optical channel (1) into two single-mode optical channel arms (2a, 2b) and another symmetric optical yjunction (6) was proposed.
Abstract: The invention relates to a Mach-Zehnder interferometer comprising a symmetrical optical y-junction (5) for dividing an input optical channel (1) into two single-mode optical channel arms (2a, 2b) and another symmetrical optical y-junction (6) for combining the optical channel arms (2a, 2b) into a multi-mode optical channel (3) which is divided by an asymmetrical optical y-junction (7) into two single-mode output optical channels (4a, 4b). The wave modes of light propagated through the optical channel arms (2a, 2b) are, when combined to said multi-mode optical channel (3), substantially equal in phase at one selected wavelength or polarization of the light and substantially reverse in phase at another selected wavelength or polarization of the light. In this way the interferometer can be used for separating or combining wavelengths or polarizations, i.e. multiplexing or demultiplexing.

Journal ArticleDOI
TL;DR: In this article, the splitting ratio of a fabricated coupler with about 0 dB splitting ratio is constant to within ± 1 dB over the large wavelength region of 1.31-1.53 μm.
Abstract: Wavelength-insensitive couplers are made by an all-fibre Mach–Zehnder interferometer forming two couplers in series. The splitting ratio of a fabricated coupler with about 0 dB splitting ratio is constant to within ±1 dB over the large wavelength region of 1.31–1.53 μm. The fluctuations of a produced coupler with about 10 dB splitting ratio are within ±1 dB in the 1.22–1.34 μm region.

Journal ArticleDOI
TL;DR: In this paper, an optically activated guided-wave Mach-Zehnder interferometer has been constructed and used to study photoinduced phase modulation in GaAs channel waveguides, achieving a π radian phase shift at the optical wavelength of 1.15 μm with modulating pulse energy of 320 pJ at an interaction length of 22 μm.
Abstract: An optically activated guided‐wave Mach–Zehnder interferometer has been constructed and used to study photoinduced phase modulation in GaAs channel waveguides. A π radian phase shift at the optical wavelength of 1.15 μm has been achieved with modulating pulse energy of 320 pJ at an interaction length of 22 μm. Our experiment also indicates that for infrared (IR) light with photon energy far below the band‐gap energy of the semiconductor material, the free carrier‐induced refractive index changes are much more significant than the free carrier‐induced absorption changes.

Journal ArticleDOI
TL;DR: Optical waveguides have been produced in Z −cut Sr0.6Ba0.4Nb2O6 (SBN:6O) by zinc diffusion from vapor phase at 1000 °C for 30 min this article.
Abstract: Optical waveguides have been produced in Z‐cut Sr0.6Ba0.4Nb2O6 (SBN:6O) by zinc diffusion from vapor phase at 1000 °C for 30 min. Values of 7.3 μm for the diffusion depth and a surface concentration of 4.2×1020 cm −3 for Zn were obtained from an electron microprobe analysis. Electro‐optic modulation at 0.83 μm wavelength has been demonstrated on a Mach–Zehnder interferometer produced by this diffusion technique. An extinction ratio of 78% and a voltage‐length (VL) product of 0.48 V cm for a TM polarized input light were obtained. Prism coupler measurements on planar waveguides diffused at 800 °C for 6 h have shown an effective index increase of 0.025 for the fundamental mode in both TE and TM polarization.

Journal ArticleDOI
TL;DR: Good preservation of modulation and ease of beam combining are strong features of these fibers, whereas the light losses that are due to imperfect coupling may present a serious problem.
Abstract: We tested such properties of single-mode and multimode fiber optics that are relevant for use in a long-baseline astronomical interferometer, and we give quantitative values for modulation, transmission, and stability of the fiber optics as measured in a Mach–Zehnder interferometer configuration. Only polarization-maintaining single-mode fibers gave satisfying results. Good preservation of modulation and ease of beam combining are strong features of these fibers, whereas the light losses that are due to imperfect coupling may present a serious problem.

Journal ArticleDOI
Masataka Shirasaki1
TL;DR: In this article, a nonlinear symmetric Mach-Zehnder interferometer is analyzed and it performs squeezing and phase-sensitive amplification through forward degenerate four-wave mixing with automatic phase matching.
Abstract: A nonlinear symmetric Mach–Zehnder interferometer is analyzed. It performs squeezing and phase-sensitive amplification through forward degenerate four-wave mixing with automatic phase matching. Since the balanced interferometer is frequency insensitive, the operation is broadband. The squeezing performance is computed numerically by means of the quantum theory without approximation. This result is compared with the squeezing characteristics derived from the linearized representation. It is found that squeezed states can be produced without excess noise. Noise reduction of an interferometric measurement and phase-preserving amplification with this squeezer are also analyzed.

Proceedings ArticleDOI
TL;DR: In this paper, a self-referencing Mach-Zehnder interferometer was incorporated into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement.
Abstract: We are incorporating a novel self-referencing Mach-Zehnder interferometer into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement. The instrument is capable of absolute wavefront measurements accurate to better than XIlOpv over a wavelength range > 300 nm without readjustment of the optical components. This performance is achieved through the design of both refractive optics and a catadioptric collimator to achromatize the Mach-Zehnder reference arm. Other features include polarization insensitivity through the use of low angles of incidence on all beamsplitters as well as an equal path length configuration that allows measurement of either broad-band or closely spaced laser-line sources. Instrument accuracy is periodically monitored in place by means of a thermally and mechanically stable wavefront reference source that is calibrated off-line with a phase conjugate interferometer. Video interferograms are analyzed using Fourier transform techniques on a computer that includes a dedicated array processor. Computer and video networks maintain distributed interferometers under the control of a single analysis computer with multiple user access.

Journal ArticleDOI
TL;DR: In this paper, a phase shift technique has been implemented to determine the phase difference between the interfering beams, which can be used to estimate mutual diffusion coefficients of gadoil systems at high pressures and temperatures.
Abstract: The present work was initiated to study nitrogen diffusion in hydrocarbons at high temperature and pressure. Such data are needed for mathematical modeling of gas diffusion into the porous matrix of fractured oil reservoirs (da Silva and Belery, 1989). Few measurements of mutual diffusion coefficients of gadoil systems at high pressures and temperatures have been reported. Erkey and Akgerman (1989) used the Taylor dispersion technique with binary mixtures of alcanes and n-octane in the temperature range from 31 to 162°C at 1.72 MPa. This appears to be the most accurate measurements for hydrocarbon mixtures at elevated pressures; the estimated accuracy was reported to be f 1%. In addition to selected nitrogen/hydrocarbon mixtures, we have therefore included the methane/n-octane system to compare with the data of Erkey and Akgerman. We chose to use the method of optical interferometry because it is sensitive, nonintrusive, and rapid. A good overview of optical methods for diffusion measurements is presented by Tyrrell and Harris (1984). In the interferometric methods, the differences in phase and amplitude between two interfering light beams are related to the light intensity. A Mach-Zehnder interferometer is particularly attractive because it allows a visualization of the cell. A phase shift technique has been implemented to determine the phase difference between the interfering beams. The diffusion cell is constructed for pressures up to 45 MPa and temperatures up to 200°C. Application of MachZehnder Interferometry The Mach-Zehnder interferometer used in this work is shown in Figure 1. Light from a He-Ne laser (A) is attenuated by a polarization filter (B) and expanded by a collimator (C). The parallel beam is split by the semitransparent mirror (D), recombined at the similar mirror (E), and observed by a video camera (not shown). The separate beam paths contain either a prism (F) or a mirror (G). The diffusion cell (H) is described in detail in the subsequent section. The mirror (G) is mounted on a piezoelectric position transducer, which enables the use of the phase shift technique (see

Journal ArticleDOI
TL;DR: It is shown that the measurement time is much shorter than that of the interferometer proposed previously and this reduction is achieved by using a different process for generation of the feedback signal in which the output of a chargecoupled device image sensor is used effectively.
Abstract: We have previously proposed a phase-locked laser diode interferometer. In that previous interferometer, however, there was substantial room for improvement in the reduction of measurement time. This reduction is achieved by using a different process for generation of the feedback signal in which the output of a chargecoupled device image sensor is used effectively. We analyze the feedback control system of the interferometer as a discrete-time system and discuss the characteristics of the interferometer. It is shown that the measurement time is much shorter than that of the interferometer proposed previously.

Journal Article
TL;DR: An interferometer having a self-pumped phase-conjugating mirror is demonstrated that eliminates the effects of turbulence or optical distortion in the beam path yet responds to any uniform phase change.
Abstract: An interferometer having a self-pumped phase-conjugating mirror is demonstrated. This device eliminates the effects of turbulence or optical distortion in the beam path yet responds to any uniform phase change.

Journal ArticleDOI
TL;DR: In this article, a fiber-optic interferometric sensor using a pair of sensing and reference birefringent singlemode fibers contacted in the length direction is proposed, where a laser beam with orthogonal linearly polarized two-frequency component waves is launched into each fiber in accordance with its bireringent axes.

Proceedings ArticleDOI
01 Aug 1991
TL;DR: In this article, a double Michelson interferometer made using integrated optics technology on silicon is presented, and a homodyne modulation and demodulation technique for a single Michelson Interferometer on silicon are described.
Abstract: For high-precision dimensional measurement, the use of an optical interferometer is often a suitable method. A Michelson interferometer is interesting because of its simple construction. However, to detect the direction of a movement the interferometer has to be modified. Two solutions are possible: first, a double Michelson interferometer made using integrated optics technology on silicon is presented; second, a homodyne modulation and demodulation technique for a single Michelson interferometer on silicon is presented. An analysis of the performance of the both solutions is described. The interferometer developed is very small and low in price compared to the present technology. Many applications of this interferometer are possible; the measurement of displacement, force, and refractive index are presented as examples.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Journal ArticleDOI
TL;DR: In this article, a nonlinear Mach-Zehnder interferometer was used to measure the photon number with a quantum non-deletion measurement of photon number, and a squeezed vacuum was applied to the unexcited port to suppress the self-phase modulation.
Abstract: A quantum nondemolition measurement of photon number taken with a nonlinear Mach–Zehnder interferometer is analyzed. When this interferometer is excited by a coherent input, it shows a large amount of noise, caused by the self-phase modulation. We demonstrate how this noise can be suppressed by applying a squeezed vacuum to the unexcited port of the interferometer.

Patent
21 Nov 1991
TL;DR: In this article, an integrated optical sensor is used to determine the absolute index of refraction of a substance with a substrate body of lithium niobate, with a single mode doubly refracting optical wave conductor.
Abstract: The integrated optical sensor determines the absolute index of refraction of a substance, esp. a liq., with a substrate body of lithium niobate. A single mode doubly refracting optical wave conductor is provided which extends along its surface between the two endfaces (7,10) of the substrate body (2). At a part of its length it is split into two arms of equal length. One arm on part of its length has a layer (19) of proton exchanged lithium niobate, insufficient for leading to a mode, and across a specified length makes optical contact with the substance, and these arms form a Mach Zehnder interferometer. The inlet face of the wave conductor is radiated with polarised light from a light source, and a light detector is acted upon with the measurement light radiated from the outlet endface of the wave conductor. The part of the optical wave conductor (6) split into the two arms (8,9) forming the Mach Zehnder interferometer is placed in the region (4) facing the outlet endface (10) of the surface of the substrate body (2). An acoustic-optical TM/TE mode converter (13) is integrated in the interferometer w.r.t. the transmission direction of the light, in a region (3) of the surface of the substrate body (2) connected to the inlet endface (7). The acoustic frequency of the TM/TE mode converter (13) is continuously alterable in a specified range. USE/ADVANTAGE - Integrated optical sensor allows determn. of absolute index of refraction of substances esp. of liquids with greater accuracy. Dispersion can be detected with help of this sensor.

Journal ArticleDOI
TL;DR: In this article, the authors used a Mach-Zehnder interferometer with acousto-optic frequency shifting to produce a 30 MHz frequency difference between the two light beams, resulting in a beat envelope on the output beam.
Abstract: We use heterodyne detection to measure optical transmittance over an unprecedented dynamic range, with high accuracy and high sensitivity. Our set-up uses a Mach-Zehnder interferometer with acousto-optic frequency shifting to produce a 30 MHz frequency difference between the two light beams, resulting in a beat envelope on the interferometer output beam. We determine the optical transmittance of a filter by inserting it into one of the interferometer arms and measuring the change in amplitude of the optical beat signal. This method allows direct comparison between optical and RF attenuators, ultimately tying optical transmittance measurements to 30 MHz RF attenuation standards in an absolute way. Using this method, we have measured filters that cover 12 decades of transmittance. We discuss a recently developed instrument that improves the accuracy and dynamic range over which the optical-RF connection can be made. This instrument functions as a lock-in amplifier with a dynamic range of up to 180 dB. In addition, we extend the technique into the infrared at 10,6 μm, where we demonstrate that transmittances of filters at room temperature can be measured with a dynamic range of more than 11 decades.