Showing papers on "Mach–Zehnder interferometer published in 2007"
TL;DR: As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
Abstract: We propose simple and compact methods for implementing all-fiber interferometers. The interference between the core and the cladding modes of a photonic crystal fiber (PCF) is utilized. To excite the cladding modes from the fundamental core mode of a PCF, a coupling point or region is formed by using two methods. One is fusion splicing two pieces of a PCF with a small lateral offset, and the other is partially collapsing the air-holes in a single piece of PCF. By making another coupling point at a different location along the fiber, the proposed all-PCF interferometer is implemented. The spectral response of the interferometer is investigated mainly in terms of its wavelength spectrum. The spatial frequency of the spectrum was proportional to the physical length of the interferometer and the difference between the modal group indices of involved waveguide modes. For the splicing type interferometer, only a single spatial frequency component was dominantly observed, while the collapsing type was associated with several components at a time. By analyzing the spatial frequency spectrum of the wavelength spectrum, the modal group index differences of the PCF were obtained from 2.83×10-3 to 4.65 ×10-3 . As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
418 citations
TL;DR: It could be shown that the imaging system in its present configuration is capable of producing three-dimensional images of objects with an overall size in the range of several millimeters to centimeters, and how the technique can be scaled for imaging of smaller objects with higher resolution.
Abstract: A three-dimensional photoacoustic imaging method is presented that uses a Mach-Zehnder interferometer for measurement of acoustic waves generated in an object by irradiation with short laser pulses. The signals acquired with the interferometer correspond to line integrals over the acoustic wave field. An algorithm for reconstruction of a three-dimensional image from such signals measured at multiple positions around the object is shown that is a combination of a frequency-domain technique and the inverse Radon transform. From images of a small source scanning across the interferometer beam it is estimated that the spatial resolution of the imaging system is in the range of 100 to about 300 mum, depending on the interferometer beam width and the size of the aperture formed by the scan length divided by the source-detector distance. By taking an image of a phantom it could be shown that the imaging system in its present configuration is capable of producing three-dimensional images of objects with an overall size in the range of several millimeters to centimeters. Strategies are proposed how the technique can be scaled for imaging of smaller objects with higher resolution.
208 citations
TL;DR: In this article, a fully fiber-based one-way quantum-key-distribution (QKD) system implementing the Gaussian-modulated coherent-state (GMCS) protocol is presented.
Abstract: In this paper, we present a fully fiber-based one-way quantum-key-distribution (QKD) system implementing the Gaussian-modulated coherent-state (GMCS) protocol. The system employs a double Mach-Zehnder interferometer (MZI) configuration in which the weak quantum signal and the strong local oscillator (LO) go through the same fiber between Alice and Bob, and are separated into two paths inside Bob's terminal. To suppress the LO leakage into the signal path, which is an important contribution to the excess noise, we implemented a scheme combining polarization and frequency multiplexing, achieving an extinction ratio of 70 dB. To further minimize the system excess noise due to phase drift of the double MZI, we propose that, instead of employing phase feedback control, one simply let Alice remap her data by performing a rotation operation. We further present noise analysis both theoretically and experimentally. Our calculation shows that the combined polarization and frequency multiplexing scheme can achieve better stability in practice than the time-multiplexing scheme, because it allows one to use matched fiber lengths for the signal and the LO paths on both sides of the double MZI, greatly reducing the phase instability caused by unmatched fiber lengths. Our experimental noise analysis quantifies the three main contributions to the excess noise, which will be instructive to future studies of the GMCS QKD systems. Finally, we demonstrate, under the ``realistic model'' in which Eve cannot control the system within Bob's terminal, a secure key rate of $0.3\text{bit}∕\text{pulse}$ over a 5km fiber link. This key rate is about two orders of magnitude higher than that of a practical Bennett-Brassard 1984 protocol QKD system.
207 citations
TL;DR: A novel Mach-Zehnder interferometer based on a fiber multimode interference structure combined with a long-period fiber grating (LPG) is proposed and demonstrated as a bending sensor.
Abstract: A novel Mach-Zehnder interferometer based on a fiber multimode interference structure combined with a long-period fiber grating (LPG) is proposed. The multimode interference is achieved through the use of a MMF section spliced between two single-mode fibers, with a length adjusted to couple a fraction of light into the cladding modes. A LPG placed after the MMF couples light back into the fiber core, completing the Mach-Zehnder interferometer. This novel configuration was demonstrated as a bending sensor.
146 citations
TL;DR: Concept, theory and simulations of a new type of waveguide device, a multiaperture Fourier-transform planar waveguide spectrometer, are presented, which significantly increases the optical throughput compared to conventional single input spectrometers.
Abstract: Concept, theory and simulations of a new type of waveguide device, a multiaperture Fourier-transform planar waveguide spectrometer, are presented. The spectrometer is formed by an array of Mach-Zehnder interferometers generating a wavelength dependent spatial fringe pattern at the array output. The input light spectrum is calculated using a discrete Fourier transformation of the output spatial fringes. The multiaperture input significantly increases the optical throughput (etendue) compared to conventional single input spectrometers. Design rules for the arrayed spectrometer are deduced from performance specifications such as wavelength range and spectral resolution. A design example with spectral resolution 0.025 nm and range 2.5 nm is presented, where the optical throughput is increased by a factor of 200 compared to a single input device.
126 citations
TL;DR: The authors' scattering-matrix-based modeling shows good agreement with the experiments and indicates ways to enhance the resonance routing functionality and demonstrates the feasibility of an integrated reconfigurable add-drop filter with actively interchangeable throughput and drop ports.
Abstract: We report a Fano resonance-based electrically reconfigurable add-drop filter using a microring resonator-coupled Mach-Zehnder interferometer (MZI) on a silicon substrate. Our experiments reveal a pair of complementary Fano resonance line shapes that can be electrically tuned and output coupled from the MZI output ports. A near symmetrical resonance peak can be flipped to a near symmetrical resonance dip by applying a forward-bias voltage of less than 1V across a laterally integrated p-i-n diode in the MZI non-resonator-coupled arm. Our scattering-matrix-based modeling shows good agreement with the experiments and indicates ways to enhance the resonance routing functionality. Our work demonstrates the feasibility of an integrated reconfigurable add-drop filter with actively interchangeable throughput and drop ports.
120 citations
TL;DR: In this paper, the visibility of interference in an electronic Mach-Zehnder interferometer in the presence of low frequency fluctuations is measured using a Gaussian phase averaging whose variance is quadratic with the bias.
Abstract: We present an original statistical method to measure the visibility of interferences in an electronic Mach-Zehnder interferometer in the presence of low frequency fluctuations. The visibility presents a single side lobe structure shown to result from a Gaussian phase averaging whose variance is quadratic with the bias. To reinforce our approach and validate our statistical method, the same experiment is also realized with a stable sample. It exhibits the same visibility behavior as the fluctuating one, indicating the intrinsic character of finite bias phase averaging. In both samples, the dilution of the impinging current reduces the variance of the Gaussian distribution.
117 citations
TL;DR: In this paper, a photonic crystal Mach-Zehnder interferometer was designed by utilizing the self-collimated beams and the bending and splitting mechanisms of line defects.
Abstract: The authors design a photonic crystal Mach-Zehnder interferometer by utilizing the self-collimated beams and the bending and splitting mechanisms of line defects. Using this interferometer, they investigate the phase shift of the reflected and transmitted self-collimated beams over the line defects. In addition, on the basis of the intensity-asymmetric unidirectional-output design, they demonstrate that such interferometers can function as an intensity detector or an ultrafast optical switch when the material of photonic crystal is nonlinear.
110 citations
TL;DR: A Bayesian phase estimation strategy is explored to demonstrate that it is possible to achieve the standard quantum limit independently from the true value of the phase shift and specific assumptions on the noise of the interferometer.
Abstract: We study a Mach-Zehnder interferometer fed by a coherent state in one input port and vacuum in the other. We explore a Bayesian phase estimation strategy to demonstrate that it is possible to achieve the standard quantum limit independently from the true value of the phase shift and specific assumptions on the noise of the interferometer. We have been able to implement the protocol by using parallel operation of two photon-number-resolving detectors and multiphoton coincidence logic electronics at the output ports of a weakly illuminated Mach-Zehnder interferometer. This protocol is unbiased, saturates the Cramer-Rao phase uncertainty bound, and, therefore, is an optimal phase estimation strategy.
108 citations
TL;DR: In this paper, a novel design for an integrated passive polarization splitter/converter combination is presented, which consists of a Mach-Zehnder interferometer with polarization converters in both arms.
Abstract: A novel design for an integrated passive polarization splitter/converter combination is presented. The device consists of a Mach-Zehnder interferometer with polarization converters in both arms. The device is analyzed using the transfer matrix method and fabricated in InGaAsP-InP. Measurement results show a splitting ratio of approximately 10 dB and a conversion of >90%. This device can be monolithically integrated with passive and active components.
86 citations
TL;DR: In this article, the temperature and voltage dependence of the quantum interference in an electronic Mach-Zehnder interferometer using edge channels in the integer quantum-Hall regime was investigated.
Abstract: We investigate the temperature and voltage dependence of the quantum interference in an electronic Mach-Zehnder interferometer using edge channels in the integer quantum-Hall regime. The amplitude of the interference fringes is significantly smaller than expected from theory; nevertheless the functional dependence of the visibility on temperature and bias voltage agrees very well with theoretical predictions. Superimposed on the Aharonov-Bohm (AB) oscillations, a conductance oscillation with a six times smaller period is observed. The latter depends only on gate voltage and not on the AB phase, and may be related to single electron charging.
TL;DR: In this article, a novel thermal design was employed to improve the device switching performance and a switching time less than 20 mus has been experimentally achieved, which clearly demonstrated the speed advantage using the new heating approach.
Abstract: Ultracompact thermooptically tuned photonic crystal waveguide (PCW) silicon-on-insulator Mach-Zehnder interferometers (MZIs) have been proposed and fabricated. A novel thermal design was employed to improve the device switching performance. Both steady-state and transient thermal analyses were performed to evaluate the thermal performance of the thermooptic MZIs. A switching time less than 20 mus has been experimentally achieved, which clearly demonstrated the speed advantage using the new heating approach. The active length of the PCW-based MZIs was 80 mum, nearly one order of magnitude shorter than the conventional silicon waveguide-based MZIs. A maximum modulation depth of 84% for a switching power of 78 mW was obtained at a wavelength of 1548 nm
TL;DR: In this article, a Mach-Zehnder interferometric all-optical switch employing intersubband transition in an InGaAs∕AlAs ∕AlSb-coupled double quantum well waveguide was developed.
Abstract: We have developed a Mach-Zehnder interferometric all-optical switch employing intersubband transition in an InGaAs∕AlAs∕AlAsSb-coupled double quantum well waveguide. The recently discovered cross-phase modulation phenomenon was utilized as the switching mechanism; the nonlinear index of refraction for transverse electric polarized light is induced by intersubband optical excitation using transverse magnetic pump light. We demonstrate the demultiplexing operation of 160Gbit∕s data signals to 10Gbit∕s using this switch. At the input control pulse energy of 8pJ, the demultiplexed signals showed an extinction ratio better than 10dB, and an error-free demultiplexing was achieved.
TL;DR: A heterodyne Mach-Zehnder interferometric microscope capable of quantitative phase imaging of biological samples with subnanometer sensitivity and frame rates up to 10 kHz is described.
Abstract: We describe a heterodyne Mach-Zehnder interferometric microscope capable of quantitative phase imaging of biological samples with subnanometer sensitivity and frame rates up to 10 kHz. We use the microscope to image cultured neurons and measure nanometer-scale voltage-dependent motions in cells expressing the membrane motor protein prestin.
TL;DR: In this article, an ultracompact and high-performance optical interleaver based on a microring assisted Mach-Zehnder interferometer using an ultrahigh-index-contrast waveguide was presented.
Abstract: We present an ultracompact and high-performance optical interleaver based on a microring assisted Mach-Zehnder interferometer using an ultrahigh-index-contrast waveguide (17% Delta). The device, a 100/200-GHz interleaver at 1.55-mum region, exhibits flat and nearly square passband and better than -30-dB stopband extinction ratio. Fiber-to-fiber loss is -2.2 dB. Passband bandwidth is 90 and 121 GHz at -1 and -20 dB, respectively. The dimension of this interleaver chip is 12times1 mm. Design optimization is also discussed for further performance improvement.
TL;DR: Neder et al. as discussed by the authors argue that the measured lobe structure in the visibility of oscillations and the phase rigidity result from a strong long-range interaction between two adjacent counter-propagating edge states, which leads to a resonant scattering of plasmons.
Abstract: We address the recently observed unexpected behavior of Aharonov-Bohm oscillations in the electronic Mach-Zehnder interferometer that was realized experimentally in a quantum Hall system [I. Neder et al., Phys. Rev. Lett. 96, 016804 (2006)]. We argue that the measured lobe structure in the visibility of oscillations and the phase rigidity result from a strong long-range interaction between two adjacent counterpropagating edge states, which leads to a resonant scattering of plasmons. The visibility and phase shift, which we express in terms of the transmission coefficient for plasmons, can be used for the tomography of edge states.
TL;DR: A near-linear phase shifter exceeding 180 degrees and a phase modulation with 2.5 Gbit/s baseband signal are obtained for a 10 GHz microwave signal by this proposed device.
Abstract: We realize a novel photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer. A near-linear phase shifter exceeding 180° and a phase modulation with 2.5 Gbit/s baseband signal are obtained for a 10 GHz microwave signal by this proposed device.
TL;DR: In this paper, a double-pass phase-sensitive surface plasmon resonance (SPR) biosensor based on a Michelson interferometer with differential phase interrogation is presented.
Abstract: A novel double-pass phase-sensitive surface plasmon resonance (SPR) biosensor based on a Michelson interferometer with differential phase interrogation is presented. The new setup provides an intrinsic resolution enhancement of up to two times in terms of achievable detection sensitivity due to an amplification effect in the SPR phase change when we place the SPR sensor head in the signal arm of the interferometer so that the interrogating optical beam traverses the sensor surface twice. Experimental results obtained from saltwater mixtures and antibody-antigen binding reactions confirmed the expected sensitivity enhancement as compared to the conventional SPR biosensor based on a Mach-Zehnder interferometer
TL;DR: In this article, shot noise in an electronic Mach-Zehnder interferometer in the fractional quantum Hall regime is used to distinguish Abelian from non-Abelian quasiparticle statistics.
Abstract: We show how shot noise in an electronic Mach-Zehnder interferometer in the fractional quantum Hall regime probes the charge and statistics of quantum Hall quasiparticles. The dependence of the noise on the magnetic flux through the interferometer allows for a simple way to distinguish Abelian from non-Abelian quasiparticle statistics. In the Abelian case, the Fano factor (in units of the electron charge) is always lower than unity. In the non-Abelian case, the maximal Fano factor as a function of the magnetic flux exceeds 1.
TL;DR: In this paper, the phase of the fringes is sensitive to changes in the surrounding environmental parameters, such as refractive index, and the application of basic Fourier techniques to analyze the transmission spectrum is presented.
Abstract: Two long-period gratings (LPGs) fabricated in series in an optical fiber form a Mach-Zehnder interferometer, producing a sinusoidal channelled spectrum within the characteristic LPG attenuation bands, which has the appearance of an interference fringe pattern. The phase of the fringes is sensitive to changes in the surrounding environmental parameters, such as refractive index. Fabrication of a number of identical cascaded LPG pairs with different separations produces independent fringe patterns of different frequencies within the attenuation bands. The application of basic Fourier techniques to analyze the transmission spectrum allows the phase of each fringe pattern to be determined independently, facilitating the differentiation of external effects acting on each interferometer
TL;DR: In this article, the authors present a successful modeling, realization and characterization of a new micro-sensor based on a convenient optical principle, namely an integrated Mach-Zehnder interferometer (MZI), designed with a view to measuring pressure disturbances due to optical path variations.
Abstract: The authors present a successful modeling, realization and characterization of a new micro-sensor based on a convenient optical principle, namely an integrated Mach–Zehnder interferometer (MZI). This MZI device is designed with a view to measuring pressure disturbances due to optical path variations. Such a system is arranged in order to work in intensity modulation scheme. Moreover, the MZI is made up of straight and bent rib optical waveguides composed of SU-8 polymer. The mainstay of the device is based on differential measurements performed by a sensing arm arranged with a micromachined membrane and actuated by a given pressure disturbance, while the second arm of the interferometer is considered as a reference one. The main parameters of each element are given by way of two modeling approaches: an optical modeling with a semi-vectorial finite difference method together with a conformal transformation, and a mechanical modeling with a finite-element method associated to the mechanical theory of membranes. So, as the pressure to be measured is applied upon the diaphragm, an optical path variation of the acting arm is induced. After the combination of both signals, the variation at the output of the system is measured. A prototype is characterized by way of a micro-optical injection bench specifically designed to allow an efficient end-fire coupling into the waveguides.
TL;DR: In this paper, a polarization-independent magneto-optical waveguide isolator using non-reciprocal phase shift for a TM mode is proposed, which allows fabrication of an integrated structure.
Abstract: A polarization-independent magneto-optical waveguide isolator using nonreciprocal phase shift for a TM mode is proposed. The isolator is a Mach-Zehnder interferometer (MZI) that is composed of transverse electric (TE)-transverse magnetic (TM) polarization converters and nonreciprocal phase shifters. The MZI induces a phase difference between the reciprocal TE and nonreciprocal TM modes that are converted to each other by the polarization converter. Since the design uses a nonreciprocal phase shift only for the TM mode, it allows fabrication of an integrated structure. This paper describes the principle of operation and its design.
TL;DR: In this article, a beam-splitter cube is used to produce two interferograms with a relative phase shift of π (rad) for spatial-carrier interferometry and flexible writing of fiber Bragg gratings.
TL;DR: In this article, the impact of coupling between input waveguides just before the input slab on chromatic dispersion was analyzed and a waveguide structure was investigated for reducing the dispersion.
Abstract: We demonstrate multi/demultiplexers with a very flat passband and small excess loss using a multi-input arrayed waveguide grating combined with a cascaded Mach-Zehnder interferometer structure. We also analyze the impact of coupling between input waveguides just before the input slab on chromatic dispersion and investigate a waveguide structure for reducing the chromatic dispersion. We fabricated flat-passband multi/ demultiplexers with 100-GHz channel spacing using 2.5%-Delta silica waveguides and experimentally investigated the dependence of their optical characteristics on design parameters to demonstrate the effectiveness of the proposed theoretical model. We obtained a very flat passband response having a 1-dB bandwidth of 0.645-0.658 nm and 20-dB bandwidth of 0.944-0.960 nm with a loss penalty due to the passband-flattening of 0.9-1.0 dB and chromatic dispersion of -22.1-17.5 ps/nm over 0.5 nm in the passband. The measured passband shape and chromatic dispersion generally agreed with the simulation results.
TL;DR: In this paper, an approach to optimize the design of the long-period grating pair as a temperature sensor device is presented, implemented by using a LPG pair with a small separation (of around 2mm) and scaling down their physical length by a factor greater than 2.
TL;DR: In this article, the authors proposed a new device configuration that incorporates a nested ring with a Mach-Zehnder interferometer, analogous to a dual-bus coupled ring resonator, with the ends of the two buses connected to form a semi-closed loop.
Abstract: We propose a new device configuration that incorporates a nested ring with a Mach-Zehnder interferometer. The nested ring is analogous to a dual-bus coupled ring resonator, with the ends of the two buses connected to form a semi-closed loop. With proper design of the length of the U-shaped loop, as well as the coupling coefficient between the ring and the waveguide, the device is capable of generating a box-shaped spectral response. This is shown to be mainly due to the double-Fano resonances that arise from constructive interference between the nested ring and the outer loop. The device is simple in that it requires only one ring, and unique in that it harnesses a pair of Fano resonances to generate a reasonably box-like filter response. The analysis is based on the transfer matrix formalism, and compared and verified with the FDTD simulations.
TL;DR: In this paper, a bidirectional data signal input scheme of a semiconductor optical amplifier-Mach-Zehnder interferometer (SOA-MZI) wavelength converter was proposed and experimentally verified for a nonreturn-to-zero (NRZ)-format signal.
Abstract: A bidirectional data signal input scheme of a semiconductor optical amplifier--Mach-Zehnder interferometer (SOA-MZI) wavelength converter was proposed and experimentally verified for a nonreturn-to-zero (NRZ)-format signal. Theoretical analyses reveal that it is possible to mitigate the patterning effect induced by cross-gain modulation (XGM) by utilizing the difference of the ratio between the XGM and cross-phase modulation on the injection directions of data signals. A hybrid integrated SOA-MZI all-optical wavelength converter, in which the coupling loss between the SOA and the silica waveguide was as small as 1 dB owing to a unique active alignment technique, was used for the experiment. We have verified the superior characteristics of the proposed operation scheme for the first time. Error-free wavelength-conversion operation for an NRZ signal at 40 Gb/s was confirmed
TL;DR: In this article, a polarization-insensitive monolithic 40-Gbps semiconductor optical amplifier (SOA)-Mach-Zehnder interferometer wavelength converter has been developed based on the photon-electron rate equation.
Abstract: A polarization-insensitive monolithic 40-Gbps semiconductor optical amplifier (SOA)-Mach-Zehnder interferometer wavelength converter has been developed. Based on the photon-electron rate equation, we optimized the dimensions of the waveguide structure to maximize the field confinement in the active layer. An InGaAsP active layer with narrow SOA waveguide effectively enables polarization-insensitive high-speed wavelength conversion. High-precision wafer processing technique enabled the fabrication of submicrometer-wide active waveguides with low current leakage. Input waveguide arrays were fabricated at intervals of 25 mum and mounted in a module with two-lens aspherical lens optics. The 40-Gbps nonreturn-to-zero wavelength conversion experiment demonstrates a clear eye opening over full C-band operation
TL;DR: In this paper, a scanning micro-interferometer, without moving parts, based on the well-known Mach-Zehnder geometry, was presented for detecting the characteristic spectral lines of a Xe-arc lamp on a 400nm wide spectral window.
TL;DR: In this paper, a phase modulation system based on the introduction of a periodic phase shift in the reference arm of the interferometers and the Fourier analysis of the output signal is presented.
Abstract: The integrated Mach–Zehnder interferometric biosensors are one of the most promising optical biosensors due to their extreme sensitivity and possibility of integration in a lab-on-a-chip. However, the periodic response of the interferometric devices complicates the interpretation of experimental results due to the ambiguity and fading of the signal. To overcome these problems we present a phase modulation system based on the introduction of a periodic phase shift in the reference arm of the interferometers and the Fourier analysis of the output signal. This system allows the direct and unambiguous detection of the phase changes induced by the biosensing measurement. As phase modulation mechanism, we propose and theoretically analyze two different magneto-optic (MO) methods compatible with the standard microelectronic processes. The phase modulators are based on silicon-on-insulator (SOI) waveguides and yttrium iron garnets (YIG) as magnetic material. The first one exploits the non-reciprocal phase shifts induced in the TM guided modes when the orientation of the magnetization of an YIG layer is rotated within the plane of the layer. On the other hand, the MO phase modulation can also rely on the birefringence induced in magnetic liquids under an external magnetic field. We demonstrate that the MO phase modulation is compatible with SOI waveguides showing very high surface sensitivity in the biosensing measurements. In addition, the MO phase modulation can be achieved by using MO interaction lengths of only a few millimetres, facilitating the integration within the interferometric biosensors.