Optimized Design and Fabrication of Mach–Zehnder Interferometer Sensor in Polymer Technology

Abstract

Without any external modulating facilities, through a precisely controlled sensing length of 11,515 μm, the integrated Mach–Zehnder interferometer sensor obtains a quadrature point and linear response in refractive index measuring range of 1.31–1.42 at the wavelength of 1,550 nm. Combined with structure optimization and surface treatment of sensing arm, the sensitivity is measured as 225.4 dB/RIU, and the sensing response time is less than 20 s to analyte solutions. Cost-efficient polymers are used as waveguide materials, and a microfluidic system is achieved.     

Nanosecond Bias-Free Mach–Zehnder Electro-Optic Switch Based on Dye-Doped Polymer DR1/SU-8 and Microstrip Line Electrode

Abstract

A bias-free Mach–Zehnder interferometer electro-optic switch is demonstrated with a dye-doped polymer Disperse Red 1 (Tokyo Chemical Industry, Co., LTD, Tokyo, Japan)/SU-8 (MicroChem Corp., Newton, Massachusetts, USA) and microstrip line electrode. The device is carefully designed and optimized for bias-free function and high-speed switching using the three-dimensional beam-propagation method and extended point-matching method, and the switch is seriously fabricated by a wet-etching technique and inductively coupled plasma etching technique for good control of dimension parameters. The measured rise time and fall time at 1,550 nm are both at the level of ~10 ns. Owing to the bias-free function and nanosecond response speed, this switch exhibits potential applications of high-speed optical routing and exchanging.     

Vibrational Spectroscopic Investigation,First Hyper Polarizability and Homo–Lumo Analysis of Tetrahydroxy-1,4Quinone Hydrate Using Density Functional Theory and Hartree-Fock Method

The FTIR and FT-Raman spectra of tetrahydroxy-1,4quinone hydrate have been recorded in the regions 4000–400 and 3500–50 cm^–1 respectively. Using the observed Fourier-transform infrared spectroscopy (FTIR) and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound has been carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by the density functional theory (DFT/B3LYP) and Hartree–Fock (HF) method with 6-311+G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamental vibrations is very small. A detailed interpretation of the infrared and Raman spectra of tetrahydroxy-1,4quinone hydrate is also reported. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule.     

Design of a spectrum-periodized polymer optical filter using arc-type Mach–Zehnder interferometer and <Emphasis Type="Italic">N</Emphasis>th order phase-generating couplers

We proposed a kind of polymer arc-type Mach–Zehnder interferometer (MZI) optical filter by employing two parallel cascaded Nth-order phase-generating couplers (PGCs). To realize periodic spectrum response with low insertion loss, a nonlinear least square method was investigated for optimizing PGC structure to satisfy periodic phase compensation (PPC) and insertion loss compensation (ILC) conditions. With the needed wavelength period of 24 nm, design and simulation on five Nth-order PGCs-based filters were performed as N changes from 0 to 4. When N=3, the optimized filter exhibits the most favorable uniform periodic response with the maximum period shift less than 0.3 nm, which is about 1/10 times of that of the traditional filter when N=0, and the insertion loss at the central wavelength of each channel is 1.39–9.98 dB. The PGC’s order N should be properly selected for low optical loss, uniform wavelength period, and feasible optimization complexity. The proposed technique can also be used to design such PGCs-based arc-type MZI filters with any other uniform wavelength period by altering the radius-difference between two arc-type MZI waveguides for CWDM networks.     

Coexistence of attractors in autonomous Van der Pol–Duffing jerk oscillator: Analysis,chaos control and synchronisation in its fractional-order form

Dynamics at infinity and a Hopf bifurcation for a Sprott E system with a very small perturbation constant are studied in this paper. By using Poincaré compactification of polynomial vector fields in \(R^3\), the dynamics near infinity of the singularities is obtained. Furthermore, in accordance with the centre manifold theorem, the subcritical Hopf bifurcation is analysed and obtained. Numerical simulations demonstrate the correctness of the dynamical and bifurcation analyses. Moreover, by choosing appropriate parameters, this perturbed system can exhibit chaotic, quasiperiodic and periodic dynamics, as well as some coexisting attractors, such as a chaotic attractor coexisting with a periodic attractor for \(a>0\), and a chaotic attractor coexisting with a quasiperiodic attractor for \(a=0\). Coexisting attractors are not associated with an unstable equilibrium and thus often go undiscovered because they may occur in a small region of parameter space, with a small basin of attraction in the space of initial conditions.