MZI Structure Research Articles

High-Sensitivity Curvature Fiber Sensor Based on Miniature Two-Path Mach-Zehnder Interferometer.

This paper introduces a new high-sensitivity curvature fiber sensor based on a miniature two-path Mach-Zehnder interferometer (MTP-MZI). The sensor is fabricated by coupling and fusing the multimode fiber (MMF) with the single-mode fiber (SMF) using arc fusion technology (AFT), resulting in a centimeter-level two-path MZI structure. The sensor represents an innovative approach to MZI coupling technology, which reduces device size, simplifies manufacturing, and lowers costs. In curvature-sensing experiments, the MTP-MZI sensor achieves a maximum curvature sensitivity of -96.70 dB/m-1 in the curvature range of 0.0418 m-1 to 0.0888 m-1, which is an extremely high sensitivity among intensity-modulated curvature sensors. Additionally, temperature-sensing measurements of the MTP-MZI sensor show a maximum temperature sensitivity of 212 pm/°C in the range of 30 °C to 70 °C, which is low temperature sensitivity and solves the cross-sensitivity problem. Thanks to the miniature two-path structure of the MTP-MZI, it provides a new perspective for developing multidimensional and multiparameter measurement methods in MZI fiber sensors.

Experimental Study of White Light Interferometry in Mach-Zehnder Interferometers Based on Standard Single Mode Fiber.

In this work, we experimentally analyzed and demonstrated the performance of an in-line Mach-Zehnder interferometer in the visible region, with an LED light source. The different waist diameter taper and asymmetric core-offset interferometers proposed used a single-mode fiber (SMF). The visibility achieved was V = 0.14 with an FSR of 23 nm for the taper MZI structure and visibilities of V = 0.3, V = 0.27, and V = 0.34 with FSRs of 23 nm, 17 nm, and 8 nm and separation lengths L of 2.5 cm, 4.0 cm, and 5.0 cm between the core-offset structure, respectively. The experimental investigation of the response to the temperature sensor yielded values from 50 °C to 300 °C; the sensitivity obtained was 3.53 a.u./°C, with R2 of 0.99769 and 1% every 1 °C in the transmission. For a range of 50 °C to 150 °C, 20.3 pm/°C with a R2 of 0.96604 was obtained.

A Micro-Mach–Zehnder Interferometer Temperature Sensing Design Based on a Single Mode–Coreless–Multimode–Coreless–Single Mode Fiber Cascaded Structure

In this paper, a temperature sensing scheme with a miniature MZI structure based on the principle of inter-mode interference is proposed. The sensing structure mainly comprises single mode–coreless–multimode–coreless–single mode fibers (SCMCSs), which have been welded together, with different core diameters. The light beam has been expanded after passing through the coreless optical fiber and is then coupled into a multimode optical fiber. Due to the light passing through the cladding and core mode of the multimode optical fiber with different optical paths, a Mach–Zehnder interferometer is formed. Moreover, due to the thermo-optic and thermal expansion effects of optical fibers, the inter-mode interference spectrum of a multimode fiber shifts when the external temperature changes. Through theoretical analysis, it is found that the change in the length of the sensing fiber during temperature detection has less of an effect on the sensitivity of the sensing structure. During the experiment, temperature changes between 20 and 100 °C are measured at sensing fiber lengths of 1.5 cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm, and 4.0 cm, respectively, and the corresponding sensitivities are 65.98 pm/°C, 72.70 pm/°C, 67.75 pm/°C, 66.63 pm/°C, 74.80 pm/°C, and 72.07 pm/°C, respectively. All the corresponding correlation coefficients are above 0.9965. The experimental results indicate that in the case of a significant change in the length of the sensing fiber, the sensitivity of the sensing structure changes slightly, which is consistent with the theory that the temperature sensitivity is minimally affected by a change in the length of the sensing fiber. Therefore, the effect of the length on sensitivity in a cascade-based fiber structure is well solved. The sensing scheme has an extensive detection range, small size, good linearity, simple structure, low cost, and high sensitivity. It has a good development prospect in some detection-related application fields.

Narrow Passband Tunable Optical Filter Based on Silicon High-Q Rings Assisted MZI Structure

Narrow Passband Tunable Optical Filter Based on Silicon High-Q Rings Assisted MZI Structure

Integrated reconstructive spectrometer with programmable photonic circuits

Optical spectroscopic sensors are a powerful tool to reveal light-matter interactions in many fields. Miniaturizing the currently bulky spectrometers has become imperative for the wide range of applications that demand in situ or even in vitro characterization systems, a field that is growing rapidly. In this paper, we propose a novel integrated reconstructive spectrometer with programmable photonic circuits by simply using a few engineered MZI elements. This design effectively creates an exponentially scalable number of uncorrelated sampling channels over an ultra-broad bandwidth without incurring additional hardware costs, enabling ultra-high resolution down to single-digit picometers. Experimentally, we implement an on-chip spectrometer with a 6-stage cascaded MZI structure and demonstrate <10 pm resolution with >200 nm bandwidth using only 729 sampling channels. This achieves a bandwidth-to-resolution ratio of over 20,000, which is, to our best knowledge, about one order of magnitude greater than any reported miniaturized spectrometers to date.

Dual-waveguide stacked graphene light modulator based on an MZI structure.

In order to solve the defects of the high driving voltage and a large volume of the existing electro-optical modulators, a double-waveguide stacked graphene optical modulator based on a Mach-Zehnder Interferometer structure is designed in this paper. First, the modulator size of traditional planar structure is effectively reduced by stacking two modulators vertically. Secondly, by changing the relative position of the electrode and the waveguide, the coupling effect of the electrode and the waveguide is enhanced, and the driving voltage is reduced. Finally, the performance of the designed electro-optic modulator is verified by the finite element method. The half-wave voltage of 0.55V · cm and the modulation bandwidth of 58.8GHz are realized on the basis of the length of 1.14mm. The insertion loss is 1.15dB, and the return loss is -44.8d B.

High-sensitivity strain sensor with micron-scale imitation dumbbell structure based on differential temperature self-compensation

A micron-sized dumbbell-like -MZI structure has been developed using hydroxide flame melt taper and arc fusion discharge, with the dumbbell rod region prepared by melt taper drawing and the dumbbell sheet region prepared by arc fusion discharge. This structure has a sensitive light intensity response in the sensing field due to a double-order mode-field coupled excitation region. The geometrical parameters of the dumbbell-like system are optimized theoretically, and the feasibility of the microstructure to achieve high strain sensing sensitivity is analyzed. Experimental results show that the microstructure has a high strain sensing sensitivity of ∼ 0.074 dB/µε and a consistent temperature sensing sensitivity over the entire monitoring wavelength range. Therefore, a light intensity-dependent temperature self-compensation calculation is proposed to achieve a uniform light intensity-strain response for each characteristic peak in the monitored wavelength domain. Since the device has a significant advantage in light intensity modulation and is not affected by polarization light perturbations, it can be used as an alternative light intensity modulation device in optical communication networks and laser research. It can also be used as a probe for medical diagnostic testing based on its enhanced evanescent field properties.

High sensitivity curvature sensor based on a double-sphere tapered no-core fiber Mach–Zehnder interferometer

A micro-fiber Mach–Zehnder interferometer (MMZI) based on a double-sphere tapered no-core fiber (DST-NCF) for curvature sensing is proposed and experimentally demonstrated. The sensor is composed of the DST-NCF sandwiched to two single-mode fibers (SMF). The DST-NCF is tapered from a double-sphere structure which is fused by no-core fiber (NCF). When light passes through the DST-NCF from SMF, higher-order modes will be excited, which will improve the sensing performance of the MMZI. This proposed structure achieves a significant improvement in curvature sensitivity for the first time by combining the characteristics of NCF, spherical format, and MMZI. When the central waist region is 2.07 mm, the maximum curvature sensitivity of the sensor is −224.64 nm/m−1, which is the highest curvature sensitivity in the MZI structure based on the spherical structure or the NCF as we have known. In addition, the maximum temperature sensitivity is −5.79 pm/℃ in the range of 40 ℃ − 90 ℃. It shows that this sensor has the characteristics of being insensitive to temperature and avoids the cross-sensitivity effect between temperature and curvature.

Efficient binary and QAM optical modulation in ultra-compact MZI structures utilizing indium-tin-oxide

A design for a CMOS-compatible active waveguide is proposed in which the epsilon-near-zero (ENZ) property of the indium-tin-oxide (ITO) is used to induce large variations in the real and imaginary parts of the waveguide effective index. The proposed waveguide comprises a TiN/HfO2/ITO metal–oxide–semiconductor (MOS) structure where the speed and power consumption are significantly improved by the application of the TiN and realization of double accumulation layers in the ITO. Simulations show the insertion loss (IL) of 0.38 dB/μm, extinction ratio (ER) of 11 dB/μm, the energy consumption of 11.87fJ/bit and electrical bandwidth of 280 GHz when the designed waveguide is used as an electro-absorption modulator. The waveguide is then used in an MZI structure to design binary and quadrature-amplitude-modulator (QAM) modulators. For binary modulator, the IL, ER, and VπLπ figures of merit are found to be 1.24 dB, 54 dB, and 6.4 V μm, respectively, which show substantial improvement over previous ITO-based designs. In the QAM design, the symmetry in the real and imaginary parts of the waveguide effective index is employed to obviate the need for additional phase shift elements. This considerably reduces the overall length of the proposed QAM modulator and improves efficiency. Simulations show the energy consumption and bit rate, of 2fJ/bit and 560 Gbps, respectively in a 4-QAM modulator with the overall length of 6.2 μm. The symmetry properties of the proposed waveguide can be further exploited to realize quadrature-phase-shift-keying (QPSK) modulators which here is used in combination with the 4-QAM to propose a design for the more advanced modulation scheme of 16-QAM. The design of ITO-based QAM modulators is here reported for the first time and the abovementioned performance parameters show the unique properties of these modulators in terms of footprint, energy consumption and modulation-speed.

High-performance silicon polarization switch based on a Mach–Zehnder interferometer integrated with polarization-dependent mode converters

Abstract As the key element for optical systems, polarization controllers with versatile functionalities are highly desired. Here, a CMOS-compatible polarization switch is proposed and realized by using a Mach–Zehnder interferometer integrated with two polarization-dependent mode converters (PDMCs) at the input/output ends. The PDMCs, which utilize the mode hybridness and adiabatic mode evolution in a silicon-on-insulator (SOI) ridge waveguide taper, provide a low-loss adiabatic transmission for the launched TE0 mode as well as efficient mode conversion from the launched TM0 mode to the TE1 mode. For the MZI structure, there are two 1 × 2 dual-mode 3-dB power splitters based on a triple-core adiabatic taper, and two thermally-tunable phase-shifters embedded in the arms. The polarization state and the polarization extinction ratio (PER) of the transmitted light can be dynamically tuned by introducing some phase difference between the MZI arms electrically. The fabricated device has an excess loss of ∼0.6 dB for the TE0 and TM0 modes. When the switch is off, the TE0 and TM0 modes go through the device without exchange. In contrast, when the switch is on, the TE0–TM0 conversion occurs and the measured PER is about 20 dB.

Design and analysis of optical switches using electro-optic effect based Mach-Zehnder interferometer structures

One of the most prominent phenomena in the Mach-Zehnder Interferometer structure is electro-optic effect-based optical switching (MZI). We generate the requisite phase difference between the optical signal contained in the two-arms of the MZI structure by utilizing the electro-optic effect. The MZI switching phenomenon, which is based on electro-optic phenomena, may be employed to perform a variety of digital logic functions. The electro-optic phenomena are discussed in full in this paper. We have supplied a detailed mathematical description, including all devices and operational parameters, for the normalized output power at the two MZI structures' ports. Using the electro-optic effect-based MZI structure, it is feasible to design an optical switching and sensing device. The proposed technique has the potential to transmit signals without electromagnetic interference up to a considerably greater distance with very low power loss. The transmission bandwidth of signal data linked with an optical waveguide is considerably greater as compared to other conventional channels of transmission. Information transmissions modified using an infrared laser light source can be transmitted over a longer distance. The article provides an electro-optic effect-based MZI structure with a full mathematical description and MATLAB simulation results that are confirmed using the OptiBPM tool.

A 35 Gb/s junction-less dual parallel Mach-Zehnder modulator for short reach interconnects

An electrostatic doping (ED) based 35 Gb/s dual-parallel Mach-Zehnder modulator (DP-MZM) for photonic integrated circuits (PICs) is proposed and analyzed. Theoretical formulation of the transfer function and linearity analysis of the proposed modulator is also presented here. The proposed modulator contains two ED-aided sub-MZMs and an ED-aided optical phase shifter (PS) in a MZI structure. Numerical simulations are performed using commercially available tools and the simulation results are presented here. From the results we estimate that the proposed DP-MZM with 400 μm long sub-MZMs can offer peak dynamic extinction ratio (ER) of 14 dB with maximum 8.7 dB of insertion loss (IL) at 10 Gb/s data rate. Using dual-tone test method, the predicted spurious free dynamic range (SFDR) of the modulator are 62.74 dB·Hz1/2 and 99.35 dB·Hz $$^{2/3}$$ for second and third harmonic intermodulation distortions (IMD2 and IMD3), respectively. From the transient analysis, the estimated maximum operating frequency and 3-dB EO bandwidth of the modulator are approximately 35.5 GHz and 32.37 GHz, respectively. At maximum data rate, 5.89 dB of dynamic ER is offered by the proposed DP-MZM for OOK modulation. Simulation verifies successful transmission of 25 Gb/s OOK modulated PRBS data stream over a 10 km standard single mode fiber (SSMF) link. Furthermore, we have shown that the proposed DP-MZM is capable of generating 50 Gb/s PAM-4 signal, which makes the modulator suitable for next-generation short-reach interconnects.

Integrated Multi-Functional Optical Filter Based on a Self-Coupled Microring Resonator Assisted MZI Structure

In general, to fit various application scenarios, different types of optical filters are needed and designed individually, which leads to high cost and long development times. Here we proposed a reconfigurable multi-functional optical filter based on self-coupled microring assisted MZI structure, which can be reconfigured into five different kinds of devices, including the optical switch, asymmetric MZI filter, ring assisted MZI filter, double injection microring resonator and self-coupled micro-ring assisted MZI filter. An analytical model was established based on the transfer matrix method to investigate the function reconfigurations, which were then verified experimentally by simply controlling the six thermo-optical phase shifters in the structure. Furthermore, our proposed reconfigurable multi-functional optical filter provides performances that are comparable to the individual devices or even better, which has the potential to be applied in the integrated optical signal processing and microwave photonics systems.

可重构自耦合微环辅助的MZI集成光子滤波器

可重构自耦合微环辅助的MZI集成光子滤波器

Silicon Photonics Radio-Over-Fiber Transmitter Using GeSi EAMs for Frequency Up-Conversion

In this letter, we present a silicon photonics radio-over-fiber transmitter with a microwave photonic up-conversion capability. The circuit consists of a pair of parallel GeSi intensity modulators (EAMs) in an MZI structure. We show that the up-converter/transmitter can up-convert 64-QAM data on a 1.5-GHz IF to any output carrier frequency in the 7–26 GHz range. This interval is only limited by the measurement equipment, as we demonstrate that the EAM has a 3-dB bandwidth exceeding 65 GHz. Furthermore, the linearity of the up-converter/transmitter is characterized and a spurious free dynamic range larger than $82~\text {dB}\cdot \text {Hz}^{2/3}$ is demonstrated. Using this system, we transmit up to 1.3-Gb/s 64-QAM data over 2-km SMF with a received 5.4% rms EVM.

Fiber In-Line Mach–Zehnder Interferometer for Gas Pressure Sensing

A Mach–Zehnder interferometer based on double off-axis twisted deformation on single mode fiber (SMF) is proposed and experimentally demonstrated for gas pressure measurements. The off-axis twisted deformation is achieved by twisting a SMF under continuous arc discharging. An open air-gap was created on the cladding of the SMF between the two off-axis deformation points by using a femtosecond laser. The cladding modes transmit through the air-gap whose refractive index is directly determined by the air pressure. The interferometer is applied for high-sensitive pressure sensing with a sensitivity of −5.183 nm/MPa and temperature cross-sensitivity of 13.3 kPa/°C. Consequently, the open air-gap added MZI structure can therefore be considered an excellent candidate as a gas pressure sensor in harsh environments due to its low cost, compact size, ease of fabrication, and all-fiber configuration.

A Novel Security Enhanced Decoder Based on XOR Detection for Optical Code Division Multiple Access System Using Multi-Diagonal Code

Objective: The main aim of this research paper is to design a security enhanced decoder based on the XOR logic gate detection technique. Methods/Statistical Analysis: An all optical XOR gate has been designed by using Semiconductor Optical Amplifier (SOA) for the secure transmission in Optical code division multiple access system. Multi Diagonal (MD) code is implemented with all optical logical gate detection using non-linear effects in semiconductor optical amplifiers. To realize the XOR gate, two identical SOAs in MZI structure have been used. Finding: The Non-Return-to-Zero (NRZ) and RZ bit format have been compared and results show that using NRZ bit format the performance is better than RZ bit format and its optimum power comes out to be 0.6mW. A new design of Multi-diagonal code has been proposed by using all optical logical gate detection considering nonlinear effects in SOA. The design has successfully worked at Bit Error Rate (BER) 8.77×10 -09 . Application/Improvements: This design having decoder based on XOR logic gate utilizing the Multi-diagonal code will have wide applications in military for the secure transmission of data.

Theoretical and experimental research on MZI frequency detection method based on orthogonal signal processing technology

A novel MZI structure was proposed by taking advantage of orthogonal signal processing technology (OSPT) and used for frequency detection. The proposed MZI was made up of a 4×4 coupler and a 2×2 coupler, and the signal processing was realized by a numerical oscilloscope. The theoretical and experimental results demonstrated that the proposed MZI structure could decrease the influence of input power vibration and the output profile was linearity and the measurement range was enlarged to more than 6 times as large as before. The achievement in this research could not only make up for the weakness of conventional MZI, but also extent the application ranges of interferometer.

A straightforward electro-optic polymer covered titanium dioxide strip line modulator with a low driving voltage

An electro-optic (EO) modulator composed of an EO polymer/titanium dioxide (TiO2) hybrid waveguide has been designed and fabricated. By using a TiO2 strip line (0.3 × 0.3 μm2 cross-section) as the core, the confinement factor in the EO polymer is optimized, thus achieving a high EO activity. The coplanar electrode spacing is tuned to enable an effective poling and a small propagation loss. The measured in-device EO coefficient is 100 pm/V at 1550 nm, with a driving voltage (Vπ) 3.2 V for the 12 mm-electrode length. The results also predict a possible Vπ of ∼1 V in a push-pull MZI structure. The EO activity of the modulator exhibited an excellent temporal stability at 85 °C for 500 h due to the high glass transition temperature of the EO polymer and the temperature-insensitive TiO2 strip line.

Implementation of sequential logic circuits using the Mach–Zehnder interferometer structure based on electro-optic effect

The electro-optic effect is one of the most important phenomena in Mach–Zehnder (MZI) interferometer structure. The Mach–Zehnder interferometer structure working on the principle of electro-optic effect behaves as the powerful optical switching device. The paper contains the discussion of electro-optic effect based MZI structure. The proper feedback mechanism with the delay unit provides the responses of optical clocked D flip-flop. The paper includes the detailed mathematical description of optical clocked D flip-flops with the MATLAB simulation result. Based on the proposed optical D-flip flop, it is possible to construct some sequential circuits such as synchronous shift registers and ripple counters. Finally, the paper includes the detailed discussion of optical sequential circuits such as synchronous shift register and ripple counter and its implementation using the MATLAB simulation. However, the concept of proposed optical clocked D flip-flop is implemented using the OptiBPM software for the proper verification of the discussed schemes. The Basic building block structures are analyzed to check the optimum performance parameters such as crosstalk, power imbalance, extinction ratio and transition losses, in order to obtain the appropriate Ti-thickness and switching voltage.