Mach–Zehnder interferometer with squeezed and EPR entangled optical fields

We study a scheme for Mach-Zehnder(MZ) interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer.Two-mode squeezed states can be changed into two types of inputs for MZ interferometer:two squeezed states and Einstein-Podolsky-Rosen(EPR) entangled states.The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned,and are measured by the balanced homodyne detection system.Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields.Since MZ interferometer can be used to realize some quantum operations,this work will have the important applications in quantum information and metrology.     

On the design of ultrafast all-optical NOT gate using quantum-dot semiconductor optical amplifier-based Mach–Zehnder interferometer

The feasibility of implementing an ultrafast NOT gate by means of a two-input Mach–Zehnder interferometer (MZI) that employs quantum-dot semiconductor optical amplifiers (QD-SOAs) is theoretically explored and shown. For this purpose a numerical treatment is conducted by modeling the propagation of strong pulses through a QD-SOA and the resultant change of the QD-SOA gain dynamics. This procedure allows to evaluate the impact of the critical parameters on the MZI complementary output port and find which is the most appropriate way to be selected and combined. The analysis of the simulation results reveals that with the non-data driven QD-SOA constantly held in the linear gain regime, the other QD-SOA, which is perturbed by the data to be logically inverted, must be operated in a nonlinear regime. This is defined by the drop of the specific QD-SOA gain by approximately 5.5 dB from its unsaturated value, which is caused by a data peak power being 4 dB higher than its saturation input power. Moreover, in order for the design to be complete, both QD-SOAs must be of medium length, provide a maximum modal gain such that their net gain exceeds by two orders of magnitude that at transparency, be biased at moderate current density and exhibit an electron relaxation time from the excited state to the ground state as fast as possible. Provided that these conditions are satisfied then a more than adequate extinction ratio can be obtained, which ensures that Boolean NOT logic is executed at 160 Gb/s both with logical correctness and high quality using QD-SOAs in a structurally simple, power efficient and operationally flexible version of the MZI.     

Simultaneous measurement of refractive index and temperature using thinned fiber based Mach–Zehnder interferometer

A novel method for simultaneous measurement of refractive index and temperature based on a small core and cladding diameters thinned fiber Mach–Zehnder interferometer (MZI) using singlemode-multimode-thinned-multimode-singlemode (SMTMS) fiber structure is proposed. Experiments indicate that the selected two interference orders have sensitivities of ?16.1936 nm/RIU and 0.0534 nm/°C, and ?23.0473 nm/RIU and 0.0575 nm/°C, respectively, among RI range from 1.3325–1.3720 and temperature range from 22 °C–82 °C. We can thus use the coefficient matrix of these two peaks to simultaneously determine the surrounding refractive index and temperature. The fabrication is easy, safe and cost effective, includes only the fusion splicing, making the device properly attractive for practical sensor applications.     

On the feasibility of ultrafast all-optical NAND gate using single quantum-dot semiconductor optical amplifier-based Mach–Zehnder interferometer

The feasibility of implementing an all-optical NAND gate for 160 Gb/s return-to-zero data pulses using a single quantum-dot semiconductor optical amplifier (QD-SOA)-based Mach–Zehnder interferometer is theoretically investigated and demonstrated. The proposed scheme exploits a modified Fredkin gate simultaneously driven by the pair of data streams between which the Boolean NAND function is to be executed, a sequence of continuous pulses and the complement of the first data input. The impact of the peak data power as well as of the QD-SOAs current density, small signal gain and electron relaxation time from the excited state to the ground state on the amplitude modulation of the switching outcome is explored and assessed by means of numerical simulation. The interpretation of the obtained results allows to specify the conditions under which the QD-SOAs must be biased to operate so that the defined performance metric becomes acceptable. By following the extracted guidelines whose satisfaction is technologically feasible and making a suitable choice for the critical parameters the NAND gate can be realized both with logical correctness and high quality at the target ultrafast data rate while being cascadable and scaleable for constructing more complex all-optical circuits.     

Multi-ion Mach–Zehnder interferometer with artificial nonlinear interactions

We propose a method to implement a Mach-Zehnder interferometry based upon a string of trapped ions with artificial nonlinear interactions. By manipulating the coupling strength between two involved internal states of the ions, we could achieve the beam splitting/recombination with NOON states. Using current techniques for manipulating trapped ions, we discuss the experimental feasibility of our scheme and analyze some undesired uncertainty under realistic experimental environment.     

Ultrafast all-optical demultiplexer based on monolithic Mach–Zehnder interferometer with integrated semiconductor optical amplifiers

A monolithically integrated and fully packaged Mach–Zehnder interferometer with semiconductor optical amplifiers (MZI-SOA) is demonstrated as polarisation-independent high-speed demultiplexer for up to 160 Gbit/s optical time division multiplexed (OTDM) data streams.     

Error scrutiny of measuring coefficients of refractive indices and Soret coefficients using Mach–Zehnder interferometer

No matter how vigilantly an experiment is performed, errors always there inside the experimental results. Since the results of laser based optical experiments are somewhat loftier in precision, commonly, sources of errors are mistreated. However, ample error scrutiny is vital in quantifying of physical parameters of liquids such as Soret and diffusion coefficients. There are two types of experimental errors, explicitly, systematic error and random error. Systematic error is associated to the apparatus and cannot be enhanced by recurrent experiments. Frequent systematic errors in Mach–Zehnder Interferometer (MZI) techniques originate from stability of laser wavelength, resolution of the electronics component etcetera. Random error is interrelated to the variation in the equivalent measurements of repeating experiment. Resolution of electronic components likewise constructs random errors by providing diverse values in the recurring experiment. Foremost, random error of MZI is caused by the environmental circumstances such as nonconformity of background light, air temperature, and air humidity. In this current amendment, a meticulous error analysis has been accomplished for evaluating thermodiffusion or Soret coefficients of hydrocarbon binary mixtures. Based on our knowledge, such a completed error scrutiny for measuring Soret coefficients using MZI does not yet exist in the literature. Study reveals that the utmost error of measuring Soret coefficient using MZI is less than 0.22%.     

Signal amplification based on the local nonlinear Mach–Zehnder interferometer

Using the phase modulation of spatial solitons, a new scheme for all-optical signal amplification has been proposed in this paper. The considered structure is composed of the nonlinear Mach–Zehnder interferometer (NMZI) with the straight control waveguide (CWG), the uniform nonlinear medium (NLM) and the linear output waveguide. The local NMZI functions like a phase shifter. The light-induced index changes in the local nonlinear MZI are responsible for the input beam routing in the uniform nonlinear medium. The coupling of the input beam to the output waveguide depends on its propagation direction in the NLM. It is shown that the signal launched at CWG can deflect the beam launched at the NMZI (input beam) and a modulated (amplified) output could be obtained at the output waveguide. Further, signal pulse may be reshaped by appropriately increasing the NLM length. In addition, amplification factor may be enhanced by increasing the NLM length and injecting an appropriate continuous wave beam along with the signal beam at CWG.     

Creating λ /3 focal holes with a Mach–Zehnder interferometer

We report the formation of doughnut-shaped focal intensity distributions with hole diameters of /3.3=232 nm full-width-at-half-maximum. The doughnut shape is created by illuminating a high-numerical-aperture lens with the output of a Mach–Zehnder interferometer, in which half of the wavefront in each arm is phase retarded by . The focal intensities are probed with a point-like scatterer and compared with the predictions of a vectorial focusing theory. The orientation of the phase-discontinuity line with respect to the electric field determines whether a strong longitudinal or a vanishing electric field is produced at the focal point. Conditions are given for creating high-contrast focal holes at the sub-micron scale. PACS 42.25.-p; 42.30.-d; 42.79.-e     

Phase precision of Mach–Zehnder interferometer in PM2.5 air pollution

This paper theoretically explores the effect of PM2.5 air pollution on the phase precision of a Mach–Zehnder interferometer. With the increasing of PM2.5 concentration, phase precision for inputs of coherent state vacuum state and inputs of coherent state squeezed vacuum state will gradually decrease and be lower than the standard quantum limit.When the value of relative humidity is increasing, the precision of two input cases is decreasing much faster. We also find that the precision for inputs of coherent state squeezed state is better than that of coherent state vacuum state when PM2.5 concentration is lower. As PM2.5 concentration increases, the precision for inputs of coherent state squeezed state decreases faster, and then the two precisions tend to be the same while the concentration is higher.     

A Mach–Zehnder interferometer based on peanut structure for temperature and refractive index measurement

Optical Review - A fiber Mach–Zehnder (M-Z) interferometer based on the peanut structure is proposed to measure the temperature and the refractive index (RI). This design includes the...     

Detecting the classical harmonic vibrations of micro amplitudes and low frequencies with an atomic Mach–Zehnder interferometer

Here we present an example of an axially symmetric spacetime, representing pure radiation, and admitting circular closed timelike curves (CTCs) on the $z= \hbox {constant plane}$ . The spacetime is regular everywhere, having no curvature singularities and is locally isometric to (non-vacuum) pp wave spacetimes. The stability of the CTCs under linear perturbations is studied and they are found to be stable from a calculation of the Lyapunov exponent for the deviation vector. We also demonstrate that the spacetime also admits non-circular CTCs which do not lie in this plane. A modification of the metric is also studied and we find that a region of this spacetime behaves like a time-machine where CTCs appear after a certain instant of time.     

Temperature-insensitive refractive index sensor based on Mach–Zehnder interferometer with two microcavities

We propose a temperature-insensitive refractive index(RI) fiber sensor based on a Mach–Zehnder interferometer. The sensor with high sensitivity and a robust structure is fabricated by splicing a short photonic crystal fiber(PCF) between two single-mode fibers, where two microcavities are formed at both junctions because of the collapse of the PCF air holes. The microcavity with a larger equatorial dimension can excite higher-order cladding modes, so the sensor presents a high RI sensitivity, which can reach 244.16 nm/RIU in the RI range of1.333–1.3778. Meanwhile it has a low temperature sensitivity of 0.005 nm/°C in the range of 33°C–360°C.     

A simple humidity sensor utilizing air-gap as sensing part of the Mach–Zehnder interferometer

A simple high-resolution refractive index (RI) and phase sensor has been demonstrated and the results numerically verified. A free space gap is employed in one arm of a Mach–Zehnder interferometer (MZI) to serve as the sensing mechanism with a physical spacing of 1.4 mm. The propagation constant of transmitted light in the MZI’s gap changes due to the small variation in the ambient RI that will further shift the optical phase of the signal. A free space optical delay line is embedded within the MZI’s other arm to set the phase reference point and compensate for variations in the optical phase difference. The ambient RI is computed by measuring the phase shift in the transmission spectrum A high-resolution sensing of 0.8 pm/%RH corresponds to phase change of 0.012°/%RH has been achieved in 1520 nm.     

Temporal and spatial evolution of air-spark switch plasma investigated by the Mach–Zehnder interferometer

An air-spark switch plasma was diagnosed by the Mach–Zehnder laser interferometer with ultra-high spatial and temporal resolution. The interferograms containing plasma phase shift information at different time were obtained. The phase shift distributions of the plasma were extracted by numerically processing the interferograms. The three-dimensional(3 D) electron density distributions of the air-spark switch plasma were then obtained. The working process of the air-spark switch was described by analyzing the temporal and spatial evolution of the plasma electron density.     

Spectral holographic imaging of transparent objects in Mach−Zehnder interferometer using acousto-optic filter

The problem of digital holographic imaging of optically transparent objects in arbitrary spectral intervals is discussed. An optical scheme based on Mach?Zehnder interferometer with acousto-optic filtration of broadband light is proposed, and an experimental setup is described. Digital holograms of test patterns and real biological objects are presented.     

Transmission characteristics of Mach–Zehnder interferometer comb filter based on thermal operation

We propose and experimentally demonstrate switchable and tunable transmission characteristics of a Mach–Zehnder interferometer comb filter based on thermal operation. Its temperature characteristics are investigated to reveal a shift in the peak wavelength position from 0.003 to 0.004 nm/°C and a tunable range of wavelength spacing of 0.76–0.90 nm for maximum and minimum effective lengths, respectively. This configuration provides the unique advantages of an all-fiber structure, tunable wavelength spacing, switchable spectral peaks, independent tuning of the center wavelength and wavelength spacing of the spectral peaks, and low polarization sensitivity. It is relatively simple to fabricate and expected to have applications in temperature fiber optic sensors and multiwavelength fiber laser sources.     

Performance of all-optical XOR gate based on two-photon absorption in semiconductor optical amplifier-assisted Mach–Zehnder interferometer with effect of amplified spontaneous emission

The performance of all-optical XOR gate is simulated and investigated. This Boolean function is realized by using a Mach–Zehnder interferometer (MZI) and exploiting the nonlinear effect of two-photon absorption (TPA) in semiconductor optical amplifier (SOA) incorporated in the MZI arms. By adjusting the input pulse intensities to be high enough, the TPA-induced phase change can be larger than the regular gain-induced phase change and hence support ultrafast operation in dual rail switching mode. The numerical study is carried out by taking into account the effect of amplified spontaneous emission (ASE). The dependence of the output quality factor ( \(Q\) -factor) on critical data signals and SOAs parameters is examined and assessed. The obtained results confirm that the XOR gate implemented with the proposed scheme is capable of operating at a data rate of 250 Gb/s with logical correctness and high output \(Q\) -factor.     

Generation of ultra-flat optical frequency comb using a balanced driven dual parallel Mach–Zehnder modulator

We propose and experimentally demonstrate an ultra-flat optical frequency comb(OFC) generator by a balanced driven dual parallel Mach–Zehnder modulator. Five- and seven-tone OFC with exactly equal intensity can be generated theoretically. Experimentally obtained five- and seven-tone OFC with flatness of 0.6 and 1.26 d B are demonstrated, respectively, which agrees well with the theoretical results.     

Frequency sextupling technique using two cascaded dual-electrode Mach–Zehnder modulators interleaved with Gaussian optical band-pass filter

A frequency sextupling technique for the generation of millimeter-wave (mm-wave) is proposed and investigated. The proposed technique is comprised of two cascaded dual-electrode Mach–Zehnder modulators (MZMs), which are interleaved with Gaussian optical band-pass filter (GOBF). The first MZM, biased at minimum transmission, is only used for optical carrier suppression modulation, and the second MZM, biased at maximum transmission, is used for both even-order optical harmonic generation and data signal modulation. The GOBF between two MZMs is used to suppress the high-order optical harmonics beyond the first-order optical harmonics. On the basis of theoretical analysis and simulated demonstrations, it is concluded that with the use of an RF signal at 10 GHz, which carries the data signal and drives the MZMs, an mm-wave signal at 60 GHz can be obtained. The simulation results show that the proposed sextuple leads to a 7 dB improvement in receiver sensitivity in comparison with the modulation technique, i.e. using two cascaded dual-electrode MZMs without GOBF. Furthermore, the eye diagrams show that the quality of generated mm-wave signal is satisfactory. The proposed technique is verified by experiments.