Waveguide-based Mach-Zehnder Interferometer Research Articles

Turning the optical properties of microcrystalline diamond films by boron ion implantation and annealing

We investigated the correlation between microstructures and optical properties of boron ion implanted microcrystalline diamond (B-MCD) thin films annealed at different temperatures. Ellipsometry characterization of B-MCD films was performed in the wavelength range of 380–1000 nm and the disperse parameters of the films such as single oscillator energy and dispersive energy were uniquely determined by using a Gaussian model. The results show that the refractive index increases from 2.18 to 2.21 to 2.28–2.29 with annealing temperature increasing from 700 to 800 °C and then it slightly decreases to 2.25–2.28 with annealing temperature further increasing to 900 °C, implying that the annealing temperature has a significant impact on the optical properties of B-MCD films. Raman spectra reveal that the full width at half maximum of diamond peak significantly decreases after 800 °C annealing, indicating a better quality of diamond crystalline. X-ray photoelectron spectroscopy results show that this sample contains higher sp3 carbon content, lower sp2 and C–O contents on the film surface after 800 °C annealing, implying that fewer defects exist. The results are of great significance for the preparation of excellent boron ion implanted microcrystalline diamond for waveguide based Mach-Zehnder Interferometer liquid sensing.

A compact realization of Feynman Reversible and NOR logic gate using Plasmonic waveguide based MZI for all-optical signal processing

The reversible logic function becomes a potential solution in the regime of optical switching and computing. The one-to-one mapping between inputs and outputs in a reversible gate is a key advantage, that prevents information loss. The reversible logic gates have shown potential applications in low-power complementary metal-oxide semiconductors and in quantum computing. Therefore, to utilize these benefits of reversible functions, we have proposed an all-optical compact circuit to realize the functioning of Feynman reversible and NOR logic gates. The proposed all-optical circuit is modeled within the footprints of 87μm by using a plasmonic metal–insulator–metal (MIM) waveguide-based Mach–Zehnder interferometer (MZI). The numerical investigation of the MZI is done by evaluating the power imbalance and extinction ratio. The results show that the optical signal propagating in a single MZI with an extinction ratio of 15.1 dB for the power difference of 0.001 W/μm (∼0.1 dB) and 0.0012 W/μm (∼0.79 dB) for logic ‘0’ and logic ‘1’, respectively. The logic ‘0’ and ‘1’ is represented by low (0.028 W/μm) and high (0.038 W/μm) power signals. At logic ‘0’ the optical signal propagates in linear arms of MZI with ‘π’ phase variation, which causes constructive interference (CI) and thrives the signal at the cross-port. For logic ‘1’ the optical signal experiences ‘0’ phase variation in linear arms of MZI, and due to destructive interference reaches its through-port. The investigated results of the proposed circuit are attained by using the finite difference time domain (FDTD) method.

A Microscale Numerical Analysis of Ex-OR and Ex-NOR Logic Gates by Using Single Plasmonic MZI

This work is focused on a detailed mathematical and numerical simulation–based analysis of Ex-OR and Ex-NOR logic gates at microscale by employing metal-insulator-metal (MIM) plasmonic waveguide–based Mach-Zehnder interferometer (MZI). The geometry of MIM waveguide is designed by considering the air as dielectric material in between silver metallic layers. The bulk plasma frequency and damping constant of silver metallic layers are considered as ωp = 140 × 1014 rad/s and $${\varvec{\gamma}}=$$ 0.4 × 1014 rad/s, respectively. A nonlinear Kerr-material with response in the order of picosecond is employed in linear arms of MZI to switch the phase of optical signals. The design of single MZI is modelled within the footprints of 19 × 3 µm with a high extinction ratio (ER) of 29 dB. The phase change property of MZI is utilized to validate the operation of Ex-OR and Ex-NOR gates. The results suggest that the proposed plasmonic-based logic gates can pave the path for efficient all optical signal processing system.

Numerical simulation of all-optical logic functions at micrometer scale by using plasmonic Metal-Insulator-Metal (MIM) waveguides

All-optical integrated circuits are quite useful in the regime of ultrafast computing to overcome the limitations of existing electronic components. In this work, we have modelled two different all-optical integrated circuits to validate the operations of OR, AND, NOR, XOR, XNOR logic gates and half-adder circuit. To cascade the integrated circuits, a plasmonic metal–insulator-metal (MIM) waveguide based Mach-Zehnder interferometer (MZI) has been used. The signal switching is attained by using MEH-PPV [poly(2-methoxy-5-(28-ethylhexyloxy)-PPV)] as nonlinear Kerr material in one linear arm of MZI. The relative linear permittivity, response time and RI of nonlinear Kerr material are 2.7225, 2.0 e−15 s, and 1.67, respectively. The switching of signal across the output ports of MZI depends on the principle of self-phase and cross-phase modulation, which depends on the power of input signals. Signal power of 0.326 W/µm and 0.828 W/µm is used for low and high intensity which corresponds to logic level ‘0′ and ‘1′, respectively. The projected integrated circuits are analyzed at the wavelength of 1550 nm with transverse magnetic (TM) polarization under the contour of perfect matched layer (PML) as boundary conditions. The results conclude that the extinction ratio (ER) of single MZI is gradually decreasing with respect to the increase in power difference. For proposed design of single MZI the attained value of ER is 24 dB at the power difference of 0.3 dB. The authentication of proposed integrated circuits is done by using finite difference time domain (FDTD) based method.

Compact multimode waveguide based temperature-insensitive Mach-Zehnder interferometer

A novel multimode waveguide based Mach-Zehnder interferometer (MZI) is demonstrated on an SOI platform with the properties of compact footprint and temperature-insensitive operation. The device can achieve a thermal dependence around 13pm/°C in a wavelength range of 40nm. Owing to the utilization of one single straight multimode waveguide, the device is naturally immune to local temperature distributions. The measured results exhibit transmissions with an extinction ratio better than 8dB and a minimum insertion loss lower than 0.31dB over the wavelength range of 1545nm-1585nm. Moreover, the proposed device is compatible with CMOS process.

On-chip integratable all-optical quantizer using strong cross-phase modulation in a silicon-organic hybrid slot waveguide.

High performance all-optical quantizer based on silicon waveguide is believed to have significant applications in photonic integratable optical communication links, optical interconnection networks, and real-time signal processing systems. In this paper, we propose an integratable all-optical quantizer for on-chip and low power consumption all-optical analog-to-digital converters. The quantization is realized by the strong cross-phase modulation and interference in a silicon-organic hybrid (SOH) slot waveguide based Mach-Zehnder interferometer. By carefully designing the dimension of the SOH waveguide, large nonlinear coefficients up to 16,000 and 18,069 W−1/m for the pump and probe signals can be obtained respectively, along with a low pulse walk-off parameter of 66.7 fs/mm, and all-normal dispersion in the wavelength regime considered. Simulation results show that the phase shift of the probe signal can reach 8π at a low pump pulse peak power of 206 mW and propagation length of 5 mm such that a 4-bit all-optical quantizer can be realized. The corresponding signal-to-noise ratio is 23.42 dB and effective number of bit is 3.89-bit.

Microfiber Mach-Zehnder interferometer embedded in low index polymer

Microfiber Mach Zehnder Interferometer (MMZI) is demonstrated by micromanipulating an optical microfiber drawn from a single mode fiber (SMF) using a flame brushing technique. The MMZI shows good interference fringes with an extinction ratio of 13 dB and a free spectral range (FSR) of 0.52 nm at 1530 nm. The MMZI is then embedded in a polymer with the refractive index of 1.36 to increase the stability and robustnes of the device. It is found that the transmission spectrum of the packaged MMZI is changed by the polymer, which increases the FSR to 0.83 nm. The degradation in transmission loss and extinction ratio are attributed to the disturbance at the coupling area during the packaging. Compared with waveguide based mach zehnder interferometer, the proposed MMZI is favoured due to easy fabrication, compact size, and easy integration with the fiber system.