Arms Of Mach-Zehnder Interferometer Research Articles

A New Superposition of Two Coherent States and its Quantum Properties

We investigate a new superposition of two coherent states via conditional measurement on a Mach-Zehnder interferometer (MZI). The resulted output state is obtained by using the superposition of two opposite coherent states with the arbitrary relative phase factors for the a-mode and vacuum state in the b-mode. It is shown that the angle of the phase shifter between the two arms of the MZI is a very important parameter in this new state.

High Performance InP-Based Polarization Beam Splitter With Reverse Bias and Injection Current

High performance InP-based polarization beam splitters (PBSs) with a symmetrical Mach–Zehnder interferometer (MZI) are theoretically and experimentally demonstrated. The p-i-n waveguide is exploited to employ the phase shifters in the two arms of the MZI. Injection current and reverse bias inducing electro-optic (EO) effects in each of the MZI arms are analysed in detail when the waveguides are aligned along both the [011] and $[ {01\bar{1}} ]$ directions. Results indicate that the birefringence from reverse bias help to realize the PBS combining with the polarization-independent carrier-induced refractive index change from the injection current. Theoretical prediction shows that the polarization extinction ratio (PER) is over 35 dB at 1550 nm for the PBSs with the waveguides aligned along both directions. Furthermore, the PBS with the waveguides aligned along the [011] direction can be adjusted more easily to work at the best operating point and get the higher birefringence which requires lower reverse bias exhibiting better performance across the C-band compared with the $[ {01\bar{1}} ]$ direction. The fabricated PBSs exhibit a PER over 19 dB (14 dB) in the wavelength range from 1525 to 1570 nm with one arm injected of 2.88 mA (0.2 mA) current and the other arm reversed biased at 5.63 V (7.89 V) when the waveguides aligned along the [011] ( $[ {01\bar{1}} ]$ ) direction. The PER of both PBSs is expected to be 20 dB across the C-band with the help of a birefringence contribution arising from inserting waveguide arms of different widths.

Design of an on-chip Fourier transform spectrometer based on waveguide Mach–Zehnder Interferometer and fluidics

An on-chip Fourier transform spectrometer based on the semiconductor waveguide Mach–Zehnder Interferometer (MZI) is proposed. The MZI is constructed by rectangular silicon-on-insulate waveguides. With the help of digital microfluidics, the sensing arm of MZI can be covered by liquid step-by-step, and as a result, the output of the MZI can be modulated accordingly. The length of the MZI arm is 3 mm for a theoretical demonstration. This spectrometer works well in the wavelength range of 1.5 μm to 1.7 μm with the spectral resolution reaching up to 3.1 nm. The performance can be further improved by extending the MZI arms along with the liquid channel.

High-resolution and fast-response optical waveguide temperature sensor using asymmetric Mach-Zehnder interferometer structure

We propose and demonstrate a high-resolution and fast-response optical waveguide temperature sensor based on asymmetric Mach-Zehnder interferometer (MZI) structure. The sensing region is composed of an asymmetric MZI structure, which consists of two different kinds of cores formed with commercial polymer materials EpoClad and Norland optical adhesive 73 (NOA 73), respectively, in the two arms. Due to the higher thermo-optic coefficient of NOA 73, the phase changes of the two MZI arms are different with the temperature which in turn induces output optical power variations, enabling simple and real-time temperature detection. The sensor exhibits a large sensitivity of −1.685 °C−1, high resolution of 1.48 × 10−3 °C and fast response time of about 510 μs. The advantages of high sensitivity and resolution, low-cost, competent integration and compatible with most biological assays make the designed sensor potential application in temperature detections of molecular analysis, biotechnology and chemical synthesis.

Thermo-Optic Mode Switch Based on an Asymmetric Mach–Zehnder Interferometer

A thermo-optic waveguide mode switch based on an asymmetric Mach–Zehnder interferometer (MZI) is demonstrated. A metal heater is deposited on one arm of the asymmetric MZI to implement switching between the LP01 and LP11 a modes. The polymer/SiO2 hybrid waveguide structure is adopted to decrease the power consumption and switching time. The fabricated device shows a mode extinction ratio of 10.5 dB with a power consumption of 15.4 mW at 1550 nm. The operation bandwidth ranges from 1525 to 1615 nm. The rise time and fall time of mode switching are 71.5 and $140.3~\mu \text{s}$ , respectively. This device has potential in configurable mode-division multiplexing systems.

On-chip Fourier transform spectrometer on silicon-on-sapphire

We designed and experimentally demonstrated an on-chip Fourier transform spectrometer on silicon-on-sapphire. The spectrometer comprises an array of twelve Mach–Zehnder interferometers (MZIs) with linearly increasing optical path delays between MZI arms. The propagation loss of 5.2 dB/cm has been experimentally observed for the strip waveguides. The retrieval of an optical spectrum is demonstrated with an inter-band cascade laser centered at 3.3 μm. The resolution is better than 10 cm−1.

Chloroform Vapor Sensor Based on Air-Gap of the Mach-Zehnder Interferometer

The proposal of this study is demonstrating a simple vapor sensor for chloroform (CHCI3) utilitizing air gap region of the Mach-Zehnder interferometer (MZI) by using a single mode optical fiber coupler (3 dB) structure. In the last few decades, flammable liquids such as chloroform have been highly used. This chemical liquid has some degrees of carcinogenic effects in humans in addition to acute and chronic exposure results like blurred vision and nausea. The two arms of MZI contain a free space gap utilized to serve the sensing mechanism by adding chemical liquid volumes (0.2, 0.4, 0.6, 0.8, and 1) ml and to set the phase difference with air-gap distance 0.5 mm. The small variation in the effective refractive index of chloroform is due to changing the propagation of the transmitted light in the MZI’s gap that will further shift the optical phase of the signal. The experimental results indicate that the output power decreased when the air gap distance is 0.5 mm, and the shifting of wavelength will increase toward blue shift when increasing the chloroform liquid volumes. A maximum wavelength shift of chloroform is 0.0251 nm when the liquid volume is 1 ml and sensitivity of chloroform is 0.0223 nm/ml at air gap distance 0.5 mm for different chloroform liquid volumes.

On-Chip Detection of Trace Gases Using Photonic Matched Filters

This theoretical modeling and simulation the design and projected performance of an on-chip detector of trace gases using photonic matched filters, with operation in the 3-5-μm mid-infrared range. The thermo-optically tuned multi-Sagnac loop Mach-Zehnder interferometer (MZI), based on the germanium-on-silicon nitride technological platform, has been adopted to detect the signature of gases with regularly spaced and narrow absorption lines. The MZI arms are comprised of an N-cascaded connection of Sagnac loop reflectors, each pair separated by a waveguide whose length is designed according to the line spacing of the gas under detection. Detection of one or two gas absorption bands using one filter band is achieved at the Drop port of an MZI filter having on each arm the apodized Hamming Bragg waveguide grating. We performed parametric analysis on the GON platform to find the design rules for the waveguide gas cell and the Hamming or multi-Sagnac filters targeted at CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> or CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> or N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O or SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> or CO. The analysis predicted good sensor performance.

Multiple-Sagnac-Loop Mach–Zehnder Interferometer for Wavelength Interleaving, Thermo-Optical Switching and Matched Filteri

This theoretical modeling and simulation paper presents design and projected performance of an on-chip thermo-optical multi Sagnac loop Mach–Zehnder interferometer (MZI), operating at C-band and 3300 nm for silicon-on-insulator and germanium-on-silicon technological platforms, respectively. The MZI arms are comprised of an N -cascaded connection of Sagnac loop reflectors, each pair separated by a waveguide whose length is designed according to the wavelength-channel spacing requirements. N is chosen according to the Butterworth filter technique to provide one spectral response having maximal flatness within the desired bandwidth. Switched, spatial routing of odd and even channels is achieved by shifting the Through and Drop MZI spectra along the wavelength axis by means of a low-power thermo-optical heater stripe atop each loop-connector that changes its effective refractive index appropriately. We examined the SOI device performance for wavelength-division multiplexed wavelength (de)interleving. The analysis predicted good performance in terms of bandwidth, insertion loss, and channel isolation for 200, 50, and 25 GHz channel spacing. For the Ge-on-Si Sagnac MZI operating in the mid infrared, we showed that a comb filter is feasible whose lines exactly match the spectral signature of methane for trace-gas sensing applications.

Temperature sensor with enhanced sensitivity based on silicon Mach-Zehnder interferometer with waveguide group index engineering.

We propose a highly-sensitive temperature sensor employing a Mach-Zehnder interferometer (MZI) based on silicon-on-insulator (SOI) platform. The waveguide widths in the two MZI arms are tailored to have different temperature sensitivities but nearly the same group refractive indices. A temperature sensor with an enhanced sensitivity of larger than 438pm/°C is experimentally demonstrated, which is over seven times larger than that of conventional silicon optical temperature sensor (about 60pm/°C for quasi-TM mode). Moreover, the sensor is easy to fabricate, only by a single mask, and no need of any polymer cladding, which makes it more robust, and can be used in lab-on-chip systems as a temperature monitor.

Dual-wavelength single-longitudinal-mode erbium-doped fiber laser with Mach–Zehnder interferometer and saturable absorber loop

A stable dual-wavelength erbium-doped fiber laser (DW-EDFL) in the single longitudinal mode (SLM) with a Mach–Zehnder interferometer (MZI) and a saturable absorber loop (SAL) is proposed and demonstrated experimentally. Dual wavelengths are obtained with different MZI arm lengths. After the first mode selection of the tunable fiber Bragg grating, SLM operation of the dual-wavelength is acquired by the SAL based on the Vernier effect and spatial hole burning, which induce an auto-tracking narrow bandwidth filter with an optical coupler and a 2 m unpumped erbium-doped fiber (EDF). The output of the DW-EDFL shows good performance, achieving 1.08 kHz at dual wavelengths of 1558.67 nm and 1558.77 nm. The interval of the dual wavelength is 0.1 nm, which has a good agreement with the theoretical value, and the peak powers are −5.508 dBm and −5.993 dBm, respectively under 170 mW pump power. Meanwhile, because of the automatic tracking of the wavelength of the SAL, the optical power instability and beating frequency fluctuation of the dual wavelength are less than 0.5 dB and 0.5 MHz, respectively, showing favorable stability.

Mathematical modeling of optical MEMS differential pressure sensor using waveguide Bragg gratings embedded in Mach Zehnder interferometer

This paper presents theoretical analysis of a silicon based micro-machined differential pressure sensor using a square shaped clamped diaphragm and surface relief waveguide Bragg gratings embedded in a Mach Zehnder interferometer (MZI). Each of the arms of the MZI has one surface relief Bragg grating embedded in it. Each grating is mounted at the edge of a micro-machined diaphragm so as to obtain maximum stress. Coupled mode theory has been used to design the directional coupler to equally couple the light into both of the arms of MZI and also to design and analyse the shifts in the wavelengths of the Bragg gratings due to applied pressures. The wavelength shift difference of the two gratings gives the differential pressure sensitivity and also eliminates the noise due to temperature variation. Simulation results indicate that the differential pressure measurement sensitivity is 0.2 pm/Pa.

Tunable optical-microwave filters optimized for 100 MHz resolution.

New continuously tunable RF-spectrum analyzers, RF receivers, and RF signal generators are proposed and analyzed for the silicon-on-insulator integrated-photonic platform at the ~1550 nm wavelength. These RF system-on-a-chip applications are enabled by a new narrowband 2x2 Mach-Zehnder interferometer (MZI) tuned filters for reconfigurable multiplexing, demultiplexing and RF channel selection. The filter can be optimized for ~100 MHz 3-dB bandwidth (BW) by utilizing N closely coupled Bragg-grating resonators to form one effective waveguide resonator in the single-mode silicon nanowire used for each MZI arm. The number of periods M within each individual resonator is selected to engineer BW in the 0.1 to 1 GHz range. Butterworth design is employed. Continuous tuning of the 100 MHz-BW devices over 18.6 GHz has been simulated by using local micron-scale thermo-optical heater stripes on the MZI arms with a temperature rise from 0 to 48K. For the case of N = 3 and 100-nm silicon side teeth, some representative performance predictions are: insertion loss (IL) = -10.7 dB, BW = 80.5 MHz and L = 113 μm for M = 58; while IL = -0.74 dB, BW = 1210 MHz and L = 86 μm for M = 44.

Electron Mobility Sensor Scheme-Based on a Mach–Zehnder Interferometer Approach

This letter presents the use of a plasmonic sensing transducer on an embedded Mach–Zehnder interferometer (MZI) arm, allowing the sensing transducer to be formed through the stacked layers of the silicon–graphene–gold materials and embedded on an MZI arm with a gripping force to allow it to be used in sensing applications. The transduction process introduces an energy conversion between the input light and the excited electron mobility within the silicon and graphene layers. That way the electron drift velocity within the gold layer can drive the plasmonic wave group velocity induced through the interaction with the graphene layers, and consequently, the electron mobility in the gold layer increases. The driven electron mobility in the gold layer, caused by the plasmonic waves from graphene in the embedded sensing layers, will affect the electron output mobility, where the relative change in the phase of the light in the silicon can be seen at the output port of the MZI. To optimize the key parameters of such a system (especially input optical power and dimensions of the gold layer), simulations are performed at various input optical powers and the results are graphically represented. A maximum sensitivity of ~ $2\times {10}^{-14}$ mV−1s−1 in electron mobility sensing is obtained through these simulations, designed to optimize the performance characteristics of the proposed sensor.

Picosecond and femtosecond asymmetric switching using a semiconductor optical amplifier-based Mach-Zehnder interferometer.

In this paper, we numerically analyze nonlinear asymmetric switching using a semiconductor optical amplifier (SOA) phase-shifter-based Mach-Zehnder interferometer (MZI), for the first time, to the best of our knowledge. The self-phase modulation (SPM) effect and nonlinear phase shift in each MZI arm are investigated for different input pulse intensities and linear gains in both picosecond and femtosecond regimes. The input light signal is split unequally over the two arms, where SOAs are placed and act as nonlinear phase shifters in each arm. The finite difference beam propagation method is used to solve the modified nonlinear Schrodinger equation to analyze the wave propagation. In this work, the main nonlinear effects in SOA, such as group velocity dispersion, Kerr effect, two-photon absorption, carrier heating, and spectral hole burning, are considered. Furthermore, the effect of SPM on distortion of the pulse shape and its spectrum, which can be used for pulse shaping in a picosecond-switching scheme, is studied. We depicted red and blue shifts that each pulse experiences in the process of switching in picosecond and femtosecond regimes, respectively. Based on the results for sub-picosecond input pulses, by controlling the bias current level in the MZI arms, the pulse distortion due to nonlinear effects of SOAs can be decreased at the switch output port, and symmetric pulse can be obtained. Switching with higher speed is possible in bulk SOAs in the femtosecond regime using asymmetric MZI-switching structure.

Noise transfer characteristics of Rydberg electromagnetically induced transparency

The transfer mechanism from the amplitude noise of the coupling light to the phase noise of the probe light in a Rydberg electromagnetic induced transparency effect derived from a ladder-type system including 6S1/2↔6P3/2↔62D5/2 of Cs atoms is demonstrated by using Mach-Zehnder interferometer and balanced homodyne detection technology. In our experiments, the transmission signal of 852 nm probe light is measured by scanning the coupling light frequency nearby the transition from 6P3/2 to 62D5/2 Rydberg state, while the frequency of the probe light is locked at the resonance transition of the 6S1/2↔6P3/2. The relative phase stability of two arms of Mach-Zehnder interferometer, which is constructed with the first order diffraction light of probe light through an acoustic-optic modulator, is accomplished by the controlled piezoelectric ceramic with the PID feedback loop. The interferences between the probe light and the reference light of Mach-Zehnder interferometer under the different relative phases are observed. The interference spectrum of probe light is in good agreement with the theoretical simulation result of the ladder-type three-level system. Therefore, we study the transfer characteristics from the frequency noise of coupling light to the phase noise of probe light when coupling light frequency resonance happens at the transition 6P3/2↔62D5/2. We find the significant suppression of the phase noise of probe light at the higher frequency noise. Moreover, we observe the characteristics of the phase noise of the probe light varying with the power of the coupling light under the different detuning degrees of coupling light. In the red detuning side, the transferred phase noise of probe light decreases with the increase of coupling light power, which is different significantly from the scenario under the blue detuning condition. The ions produced in the ionization process of Rydberg atoms will form the local electric field that would cause the energy level of Rydberg states to shift. The investigation of the noise transfer between the coupling light and probe light in the Rydberg electromagnetically induced transparency effect is important for understanding the coherence mechanism of ladder-type system and the some potential applications, such as in Rydberg-atom-based electric field metrology.

Refractive index retrieving of polarization maintaining optical fibers

Abstract In this paper, the cross-section images, of two different types of polarization maintaining (PM) optical fibers, are employed to estimate the optical phase variation due to transverse optical rays passing through these optical fibers. An adaptive algorithm is proposed to recognize the different areas constituting the PM optical fibers cross-sections. These areas are scanned by a transverse beam to calculate the optical paths for given values of refractive indices. Consequently, the optical phases across the PM optical fibers could be recovered. PM optical fiber is immersed in a matching fluid and set in the object arm of Mach-Zehnder interferometer. The produced interferograms are analyzed to extract the optical phases caused by the PM optical fibers. The estimated optical phases could be optimized to be in good coincidence with experimentally extracted ones. This has been achieved through changing of the PM optical fibers refractive indices to retrieve the correct values. The correct refractive indices values are confirmed by getting the best fit between the estimated and the extracted optical phases. The presented approach is a promising one because it provides a quite direct and accurate information about refractive index, birefringence and beat length of PM optical fibers comparing with different techniques handle the same task.

Spectral detection of graphene and graphene oxide with SU-8 based asymmetry tripled-Arm Mach Zehnder

This paper reports the experimental application of the fabricated SU-8 based triple arm Mach-Zehnder interferometer (MZI) in the detection of graphene and graphene oxide. A standard MZI has two arms in its structure. In our design, we combine two MZIs with different dimensions together in a way that a short arm MZI replaces one longer arm of the larger MZI. The parallel connections of the two MZIs with a common arm would enhance the overall sensitivity of the sensor. The measurands graphene and graphene oxide with almost similar refractivity has been applied to sensing arms of the MZI in separate steps. The equidistance picometric spectral shifts corresponding to each measurands over the operating wavelength of 1550nm are observed and is suitable for detection of graphene and graphene oxide.

Synchronous driving scheme for silicon-based optical switches to critically compensate for thermo-optic effect in carrier injection.

The switching performance of high-speed optical-switching-integrated chips is to a great extent dependent on the carrier injection technique, which is accompanied by the thermo-optic effect. In this paper, we put forward a synchronous driving scheme for the silicon-based Mach-Zehnder interferometer (MZI) optical switches, which is capable of critically compensating for the temperature variation with carrier injection to the p-i-n diode on one arm of the MZI by applying a synchronous modulating voltage to the silicon resistive heater on the other MZI arm. The synchronous compensation mechanism is identified by experiments and simulation. Our experimental data show that, by comparison with the traditional driving scheme, the synchronous driving scheme can improve the extinction ratio by 1dB, along with a better switching waveform.

Measurement of audio signal by using low-frequency squeezed light

Measurement of audio signal plays a significant role in many applications, such as gravitational wave detection, bio-particle imaging and magnetometer. In this paper, low-frequency squeezed light is generated by a non-degenerate optical parametric amplifier. In order to avoid the effect of injected light on low-frequency squeezing, an auxiliary laser is used to lock the length of non-degenerate optical parametric amplifier and a method of locking quantum noise is employed to lock the phase between the local light and the squeezed light. By isolating the vibration noises at low-frequency and reducing back action of parasitic interference, the squeezing of (7.1±0.1) dB takes place at 19 kHz. Then the squeezed light is injected into the Mach-Zehnder interferometer to measure an audio signal which drives a piezoelectric transducer to generate a small phase variation between two arms of Mach-Zehnder interferometer. According to the low-frequency squeezing, we realize experimentally the measurement of phase signal at audio frequency which exceeds the shot-noise limit of (3.0±0.4) dB. The experiment provides technical supports for the generation of low-frequency squeezed light and the measurement of audio signal. Furthermore it can be extended to other quantum measurements, such as high-precision magnetometer and measurement of small-displacement.