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Showing papers on "Mach–Zehnder interferometer published in 2008"


Journal ArticleDOI
TL;DR: In this paper, a fiber Mach-Zehnder interferometer was realized by concatenating two singlemode fiber tapers separated by a middle section, which had a minimum insertion loss of 3 dB and maximum interferometric extinction ratio over 20 dB.
Abstract: A novel refractive index (RI) sensor based on a fiber Mach-Zehnder interferometer was realized by concatenating two single-mode fiber tapers separated by a middle section. The proposed device had a minimum insertion loss of 3 dB and maximum interferometric extinction ratio over 20 dB. The resolution (0.171 nm) of the two-taper sensor to its surrounding RI change (0.01) was found to be comparable to that (0.252 nm) of similar structures made from an identical long-period gratings pair, and its ease of fabrication makes it a low-cost alternative to existing sensing applications.

334 citations


Journal ArticleDOI
TL;DR: In this article, the authors present conceptual designs of an emerging class of logic gates, including NOT, NOR, and NAND, that use traveling spin waves (SWs) in the gigahertz range and that are based on a Mach-Zehnder-type SW (MZSW) interferometer.
Abstract: We present conceptual designs of an emerging class of logic gates, including NOT, NOR, and NAND, that use traveling spin waves (SWs) in the gigahertz range and that are based on a Mach–Zehnder-type SW (MZSW) interferometer. In this MZSW interferometer, logical input and output signals are achievable by the application of currents in order to control the phases that are accumulated by propagating SWs and by either destructive or constructive SW interference, respectively. In this article, the operation mechanism underlying a NOT gate function using a single MZSW interferometer is described and demonstrated numerically. The MZSW interferometer can itself become a NOT gate and be combined in its parallel and serial configurations to form NAND and NOR gates, respectively, which represent emerging classes of universal logic functions for microwave information signal processing.

266 citations


Journal ArticleDOI
TL;DR: In this paper, a fiber Michelson interferometer refractive index (RI) sensor with a single core-offset attenuator and a layer of ~ 500-nm gold coating was demonstrated.
Abstract: Mach-Zehnder and Michelson interferometers using core-offset attenuators were demonstrated. As the relative offset direction of the two attenuators in the Mach-Zehnder interferometer can significantly affect the extinction ratio of the interference pattern, single core-offset attenuator-based sensors appear more robust and repeatable. A novel fiber Michelson interferometer refractive index (RI) sensor was subsequently realized by a single core-offset attenuator and a layer of ~ 500-nm gold coating. The device had a minimum insertion loss of 0.01 dB and maximum extinction ratio over 9 dB. The sensitivity (0.333 nm) of the new sensor to its surrounding RI change (0.01) was found to be comparable to that (0.252 nm) of an identical long period gratings pair Mach-Zehnder interferometric sensor, and its ease of fabrication makes it a low-cost alternative to existing sensing applications.

213 citations


Journal ArticleDOI
TL;DR: The MNF-assembled MZIs demonstrated here show advantages of easy fabrication, in situ tunability, and compact size.
Abstract: We demonstrate Mach-Zehnder interferometers (MZI) assembled using optical microfibers or nanofibers (MNFs) drawn from silica fibers and tellurite glasses. As-assembled MZIs, with dimensions of tens to hundreds of micrometers, show good interference fringes with extinction ratios of approximately 10 dB. The path-length difference of the MZI can be tuned by micromanipulation under an optical microscope. The MNF-assembled MZIs demonstrated here show advantages of easy fabrication, in situ tunability, and compact size.

184 citations


Journal ArticleDOI
TL;DR: In this paper, a distributed fiber-optic vibration sensing system is proposed and demonstrated by employing a ring Mach-Zehnder interferometer (MZI) structure as the sensing section, both position and frequency can be determined by combining two phase signals from the ring configuration.

137 citations


Journal ArticleDOI
TL;DR: In this paper, a simple physical model was proposed to explain the dephasing in the electronic Mach-Zehnder interferometer at filling factor 2, which explains the unusual lobe-type structure in the visibility of Aharonov-Bohm oscillations, phase rigidity, and the asymmetry of the visibility as a function of transparencies of quantum point contacts.
Abstract: We propose a simple physical model which describes dephasing in the electronic Mach-Zehnder interferometer at filling factor $\ensuremath{ u}=2$. This model explains very recent experimental results, such as the unusual lobe-type structure in the visibility of Aharonov-Bohm oscillations, phase rigidity, and the asymmetry of the visibility as a function of transparencies of quantum point contacts. According to our model, dephasing in the interferometer originates from strong Coulomb interaction at the edge of two-dimensional electron gas. The long-range character of the interaction leads to a separation of the spectrum of edge excitations on slow and fast mode. These modes are excited by electron tunneling and carry away the phase information. The new energy scale associated with the slow mode determines the temperature dependence of the visibility and the period of its oscillations as a function of voltage bias. Moreover, the variation of the lobe structure from one experiment to another is explained by specific charging effects, which are different in all experiments. We propose to use a strongly asymmetric Mach-Zehnder interferometer with one arm being much shorter than the other for the spectroscopy of quantum Hall edge states.

124 citations


Journal ArticleDOI
TL;DR: It is shown that the generation of entanglement of two heavily macroscopic mirrors is feasible with state of the art techniques of high-precision laser interferometry and the connection between the Generation of Entanglement and the standard quantum limit (SQL) for a free mass is presented.
Abstract: We show that the generation of entanglement of two heavily macroscopic mirrors is feasible with state of the art techniques of high-precision laser interferometry. The basis of such a demonstration would be a Michelson interferometer with suspended mirrors and simultaneous homodyne detections at both interferometer output ports. We present the connection between the generation of entanglement and the standard quantum limit (SQL) for a free mass. The SQL is a well-known reference limit in operating interferometers for gravitational-wave detection and provides a measure of when macroscopic entanglement can be observed in the presence of realistic decoherence processes.

100 citations


Journal ArticleDOI
TL;DR: An optimized air-hole size in the HOF provided two unique optical paths; the leaky waveguide modes through the central air hole and the radiation channel into the silica cladding, which enabled a compact MZI configuration with enhanced optical performances, such as high visibility, high temperature sensitivity, and wide dynamic range.
Abstract: We report on an ultracompact fiber optic Mach-Zehnder interferometer (MZI) using a novel concatenated structure, single-mode-fiber (SMF)-hollow optical fiber (HOF)-SMF. An optimized air-hole size in the HOF provided two unique optical paths; the leaky waveguide modes through the central air hole and the radiation channel into the silica cladding, which enabled a compact MZI configuration with enhanced optical performances, such as high visibility, high temperature sensitivity, and wide dynamic range.

98 citations


Journal ArticleDOI
TL;DR: Various all-optical logic gates by using the local nonlinear Mach-Zehnder waveguide interferometer structure with two straight control waveguides have been proposed to perform XOR/NXOR, AND/NAND, and OR/NOR logic functions.
Abstract: We propose new all-optical logic gates containing a local nonlinear Mach-Zehnder interferometer waveguide structure. The light-induced index changes in the Mach-Zehnder waveguide structure make the output signal beam propagate through different nonlinear output waveguides. Based on the output signal beam propagating property, various all-optical logic gates by using the local nonlinear Mach-Zehnder waveguide interferometer structure with two straight control waveguides have been proposed to perform XOR/NXOR, AND/NAND, and OR/NOR logic functions.

90 citations


Journal ArticleDOI
TL;DR: In this paper, the precision of various interferometric measurements can be enhanced by using entangled states of light, and an experiment demonstrates that all the metrological advantages of the famed Hong-Ou-Mandel quantum interferometer can be realized even with purely classical light.
Abstract: The precision of various interferometric measurements can be enhanced by using entangled states of light. Now an experiment demonstrates that all the metrological advantages of the famed Hong–Ou–Mandel quantum interferometer can be realized even with purely classical light.

89 citations


Journal ArticleDOI
TL;DR: In this article, the authors present an experiment using a single apparatus that demonstrates the wave aspect, the particle aspect, and most importantly, their coexistence, based on a Mach-Zehnder interferometer in which a light beam is attenuated so that at each instant there is only a single photon in the interferometers.
Abstract: The wave-particle duality of light plays a fundamental role in introductory courses on quantum mechanics. Traditionally the wave and particle aspects of light are demonstrated in separate experiments which makes it difficult for students to understand their complementary nature. We present an experiment using a single apparatus that demonstrates the wave aspect, the particle aspect, and most importantly, their coexistence. The apparatus is based on a Mach-Zehnder interferometer in which a light beam is attenuated so that at each instant there is only a single photon in the interferometer. In this way the observation of single photon interference becomes possible. By integrating the single photon events in a storage oscilloscope the evolution toward classical interference fringes can be shown in real time. A second strong laser beam, derived from the same pointer, but slightly displaced, traverses the interferometer at the same time, allowing the simultaneous demonstration of wave aspects. Special features of the setup are low cost, simplicity, didactical power and suitability for presentations in large lecture halls using both multimedia projections and audible signals.

Journal ArticleDOI
TL;DR: An electrically driven semiconductor single-photon source capable of emitting photons with a coherence time of up to 400 ps under fixed bias is reported and it is shown that increasing the injection current causes the coherenceTime to reduce.
Abstract: We report an electrically driven semiconductor single-photon source capable of emitting photons with a coherence time of up to 400 ps under fixed bias. It is shown that increasing the injection current causes the coherence time to reduce, and this effect is well explained by the fast modulation of a fluctuating environment. Hong-Ou-Mandel-type two-photon interference using a Mach-Zehnder interferometer is demonstrated using this source to test the indistinguishability of individual photons by postselecting events where two photons collide at a beam splitter. Finally, we consider how improvements in our detection system can be used to achieve a higher interference visibility.

Journal ArticleDOI
TL;DR: The nondestructive observation of Rabi oscillations on the Cs clock transition is reported on and the observed spin fluctuations are shown to be close to the standard quantum limit.
Abstract: We report on the nondestructive observation of Rabi oscillations on the Cs clock transition. The internal atomic state evolution of a dipole-trapped ensemble of cold atoms is inferred from the phase shift of a probe laser beam as measured using a Mach-Zehnder interferometer. We describe a single color as well as a two-color probing scheme. Using the latter, measurements of the collective pseudospin projection of atoms in a superposition of the clock states are performed and the observed spin fluctuations are shown to be close to the standard quantum limit.

Journal ArticleDOI
Daewoong Kim1, Assia Barkai1, Richard Jones1, Nomi Elek1, Hat Nguyen1, Ansheng Liu1 
TL;DR: A monolithically integrated eight-channel optical multiplexer (Mux) with a 400 GHz channel spacing ~1550 nm is presented based on a silicon-on-insulator rib waveguide and an asymmetric Mach-Zehnder interferometer.
Abstract: A monolithically integrated eight-channel optical multiplexer (Mux) with a 400 GHz channel spacing ~1550 nm is presented based on a silicon-on-insulator rib waveguide and an asymmetric Mach-Zehnder interferometer. All channels were optimized independently with integrated heaters. The fully tuned Mux shows an adjacent channel isolation of ~13 dB, an excess loss of ~2.6 dB, and a channel uniformity of ~1.5 dB over a 25 nm wavelength span. In addition, the phase tuning efficiency for different interlevel dielectric layer thicknesses and thermal crosstalk were investigated.

Journal ArticleDOI
TL;DR: A passive ring-assisted Mach-Zehnder interferometer optical interleaver comprising a Y-bench, a 3-dB directional coupler, a ring-resonator, and a delay line is proposed, which demonstrates a flat-top spectral response.
Abstract: A passive ring-assisted Mach-Zehnder interferometer optical interleaver comprising a Y-bench, a 3-dB directional coupler, a ring-resonator, and a delay line is proposed. The interleaver is fabricated with 300 nm x 300 nm silicon wires on silicon-on-insulator. The fabricated interleaver demonstrates a flat-top spectral response. The measured free-spectral range is approximately 4 nm, the insertion loss is approximately -8 dB, and the crosstalk is <- 10 dB. Both the experimental and simulation results are in good agreement.

Journal ArticleDOI
TL;DR: In this article, the authors presented the parameter design and performance analysis of a 160Gb/s all-optical XOR gate based on cross-gain modulation (XGM) in a nonlinear Mach-Zehnder interferometer (MZI) with quantum dot semiconductor optical amplifiers (QD-SOAs).

Journal ArticleDOI
TL;DR: In this article, a planar refractive index sensor based on a surface plasmon polariton (SPP) excited with a Bragg grating was proposed for phase interrogation.
Abstract: We present what we believe is a novel theoretical scheme for phase interrogation of a planar refractive index sensor based on a surface plasmon polariton (SPP) excited with a Bragg grating. The device is a Mach-Zehnder interferometer (MZI), which offers a simple integrated optical solution to monitor relative phase variations in waveguides. The principle of operation for this device is based on the significant phase change in the field of a waveguide mode transmitted through a grating. This phase change occurs during the SPP excitation and is caused by the change in the refractive index of the sensed layer in contact with the metal layer supporting the SPP, operating at commercialized telecommunications wavelengths.

Journal ArticleDOI
TL;DR: Using an array of m x n nonlinear ring resonators coupled to the upper arm of a Mach-Zehnder interferometer (MZI), the possibility of designing an all-optical switching device with a threshold intensity as low as 15 mW/m(2) and switching window of approximately 35 ps is shown.
Abstract: Using an array of m×n nonlinear ring resonators (m=1, 3, 5, and n=1, 2, 3) coupled to the upper arm of a Mach-Zehnder interferometer (MZI), we have proposed an all-optical switch structure. Using a 5×3 array, we have shown the possibility of designing an all-optical switching device with a threshold intensity as low as 15 mW/m2 and switching window of ~35 ps. While using m×1 arrays, we have achieved switching windows smaller than 10 ps, at the expense of higher switching thresholds, ranging from 37 to 55 mW/m2. The whole structure is based on a square lattice photonic crystal of lattice constant a=600 nm, formed by rods of radius r=90 nm in an air background. The linear rods' refractive index is taken to be the same as that of Si0.75Ge0.25; i.e., nr=3.6, whereas the nonlinear rod's refractive index and Kerr index parameter are taken to be n0=1.4 and n2=10−14 m2/W. The center wavelength at which the nonlinear rings are designed to make the resonance is taken to be λ0=1550 nm in free space.

Journal ArticleDOI
TL;DR: Comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics of Mach-Zehnder silicon optical modulators based on carrier-injection.
Abstract: We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VπL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation with doping concentration is explored and found to be important for the modulator characteristics.

Journal ArticleDOI
TL;DR: The unbalanced differential detection of a 3x3 Mach-Zehnder interferometer has increased the signal-to-noise ratio by at least 4 dB compared to the commonly used balanced detection technique, due to better utilization of optical power.
Abstract: Quadrature interferometry based on 3x3 fiber couplers could be used to double the effective imaging depth in swept-source optical coherence tomography. This is due to its ability to suppress the complex conjugate artifact naturally. We present theoretical and experimental results for a 3x3 Mach-Zehnder interferometer using a new unbalanced differential optical detection method. The new interferometer provides simultaneous access to complementary phase components of the complex interferometric signal. No calculations by trigonometric relationships are needed. We demonstrate a complex conjugate artifact suppression of 27 dB obtained in swept-source optical coherence tomography using our unbalanced differential detection. We show that our unbalanced differential detection has increased the signal-to-noise ratio by at least 4 dB compared to the commonly used balanced detection technique. This is due to better utilization of optical power.

Journal ArticleDOI
TL;DR: Push-pull driven Mach-Zehnder intensity modulators with a record low drive voltage of 0.3V were realized in substrate removed very compact GaAs∕AlGaAs optical waveguides at 1.55μm as discussed by the authors.
Abstract: Push-pull driven Mach–Zehnder intensity modulators with a record low drive voltage of 0.3V were realized in substrate removed very compact GaAs∕AlGaAs optical waveguides at 1.55μm. The modulator electrode is 7mm long, corresponding to a drive voltage length product of 0.21Vcm. The modulation is due to linear electro-optic and carrier depletion effects and has a high speed potential. The propagation loss was 8dB∕cm, making moderately long devices possible.

Journal ArticleDOI
TL;DR: An optical sensor based on a monolithically integrated Mach-Zehnder interferometer comprising a liquid-core waveguide in one of the optical paths is demonstrated and polarization dependence of the device response is analyzed.
Abstract: We demonstrate experimentally an optical sensor based on a monolithically integrated Mach-Zehnder interferometer comprising a liquid-core waveguide in one of the optical paths. The device is fabricated with a technique for self-forming microchannels in silica-on-silicon using standard photolithography and deposition processes. Refractometry with a resolution of better than 4×10-6 is demonstrated using the thermo-optic effect of the liquid medium to vary its refractive index. The polarization dependence of the device response is analyzed.

Journal ArticleDOI
TL;DR: A new scheme for generating vortex laser beams from a laser consisting of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer configuration, which allows controlled construction of p x p vortex array beams from Ince-Gaussian modes, IG(e) (p,p) modes.
Abstract: This paper proposes a new scheme for generating vortex laser beams from a laser. The proposed system consists of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer configuration. This configuration allows controlled construction of p x p vortex array beams from Ince-Gaussian modes, IG(e) (p,p) modes. An incident IG(e)(p,p) laser beam of variety order p can easily be generated from an end-pumped solid-state laser system with an off-axis pumping mechanism. This study simulates this type of vortex array laser beam generation, analytically derives the vortex positions of the resulting vortex array laser beams, and discusses beam propagation effects. The resulting vortex array laser beam can be applied to optical tweezers and atom traps in the form of two-dimensional arrays, or used to study the transfer of angular momentum to micro particles or atoms (Bose-Einstein condensate).

Journal ArticleDOI
TL;DR: An improved version of a digital-to-analog converter (DAC) based on a multi-electrode Mach-Zehnder interferometer (MZI) is presented and analyzed and reveals that dynamic range and linearity are significantly improved which is translated to increased resolution and reduced quantization errors.
Abstract: An improved version of a digital-to-analog converter (DAC) based on a multi-electrode Mach-Zehnder interferometer (MZI) is presented and analyzed. The device described has superior performance regarding both linearity and dynamic range. The improvements are achieved by utilizing a special mapping method between the analog input and the digital sequence applied to the device, and by an optimized sectioning method for the electrodes. Further improvement in linearity is attained by allowing the number of electrodes M to be larger than the number of digitization bits N (M > N). An analytical and systematic method for performing the mapping and selecting the electrodes' sizes is explicitly described and shown to be optimal. A comparison of the proposed approach to previously reported biased MZI reveals that dynamic range and linearity are significantly improved which is translated to increased resolution and reduced quantization errors. It follows from the optimization process that quantization and nonlinearity errors can be reduced to any extent by appropriately increasing the number of electrodes.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate real-time detection of self-interfering electrons in a double quantum dot embedded in an Aharonov-Bohm interferometer, with visibility approaching unity.
Abstract: We demonstrate real-time detection of self-interfering electrons in a double quantum dot embedded in an Aharonov-Bohm interferometer, with visibility approaching unity. We use a quantum point contact as a charge detector to perform time-resolved measurements of single-electron tunneling. With increased bias voltage, the quantum point contact exerts a back-action on the interferometer leading to decoherence. We attribute this to emission of radiation from the quantum point contact, which drives non-coherent electronic transitions in the quantum dots.

Journal ArticleDOI
TL;DR: In this article, the authors report the fabrication and characterization of an integrated optofluidic Mach-Zehnder interferometer based on liquid core waveguides, where the light is confined inside a low refractive index liquid core by an antiresonant reflecting optical waveguide.
Abstract: We report the fabrication and the characterization of an integrated optofluidic Mach–Zehnder interferometer based on liquid core waveguides. The light is confined inside a low refractive index liquid core by antiresonant reflecting optical waveguide. Several asymmetric Mach–Zehnder interferometers have been realized with standard silicon technology. An optical characterization of the devices has been carried out by measuring the spectrum of optical transmitted intensity from two different Mach–Zehnder configurations. The results show that interferometers with a good visibility can be achieved in good agreement with the theoretical results.

Journal ArticleDOI
TL;DR: A solution to the interaction Hamiltonian presented here shows that the interference visibility has a lobe pattern with applied bias that has a period proportional to the average path length and independent of the path length difference, together with a phase rigidity.
Abstract: We investigate theoretically the behavior of the current oscillations in an electronic Mach-Zehnder interferometer (MZI) as a function of its source bias. Recently, the MZI visibility data showed an unexplained lobe pattern with a peculiar phase rigidity. Moreover, the effect did not depend on the MZI path length difference. We argue that these effects may be a new many-body manifestation of particle-wave duality in quantum mechanics. When biasing the interferometer sources so much that multiple electrons are on each arm at any instant in time, quantum shot noise (a particle phenomena) must affect the interference pattern of the electrons that create it. A solution to the interaction Hamiltonian presented here shows that the interference visibility has a lobe pattern with applied bias that has a period proportional to the average path length and independent of the path length difference, together with a phase rigidity.

Journal ArticleDOI
TL;DR: It is demonstrated that the shot noise at the beam splitter of the interferometer generates an ensemble of nonequilibrium electron density configurations and that electron interactions induce configuration-specific phase shifts of an interfering electron.
Abstract: We study nonequilibrium dephasing in an electronic Mach-Zehnder interferometer. We demonstrate that the shot noise at the beam splitter of the interferometer generates an ensemble of nonequilibrium electron density configurations and that electron interactions induce configuration-specific phase shifts of an interfering electron. The resulting dephasing exhibits two characteristic features, a lobe pattern in the visibility and phase jumps of pi, in good agreement with experimental data.

Journal ArticleDOI
TL;DR: In this article, a fiber Bragg grating (FBG) sensor multiplexing scheme based on frequency-shifted interferometry was proposed, in which a frequencyshifting element was placed asymmetrically in one arm of a folded Mach-Zehnder interferometer.
Abstract: We demonstrate a fiber Bragg grating (FBG) sensor multiplexing scheme based on frequency-shifted interferometry, in which a frequency-shifting element is placed asymmetrically in one arm of a folded Mach-Zehnder interferometer. The location and the reflection spectrum of each FBG sensor in an array can be resolved through Fourier transform. We experimentally investigated this multiplexing scheme in an FBG array constructed by ten low-reflectivity (~4%) sensors. A signal-to-noise ratio of 48 dB was achieved with crosstalk below 34 dB.

Journal ArticleDOI
TL;DR: In this article, a Mach-Zehnder modulator with capacitively loaded traveling-wave electrodes (CL-TWEs), which have segmented structures along the optical waveguides, is presented.
Abstract: InP-based Mach-Zehnder modulators with capacitively loaded traveling-wave electrodes (CL-TWEs), which have segmented structures along the optical waveguides, are presented. Devices with various structural parameters for gap length (the length between adjacent segmented phase modulators) and total active length were fabricated and investigated both optically and electrically. Excellent characteristics such as characteristic impedance matching to 50 Omega and low electrical propagation losses were obtained. Using the optimum structures, 40- and 10-Gb/s large signal operations were successfully performed with peak-to-peak driving voltages of 3.0 and 1.2 V, respectively. The effects of structural parameters, such as gap length and total active length on electrical and optical modulation properties, are discussed.