Wavelength and throughput tuning of FORR-based optical filter using Sagnac effect

In this paper, analysis of tunable optical filter based on Sagnac effect tuning is presented using a fiber-optic ring resonator (FORR) and the responses of the filters for different FORR and Sagnac loop parameters under steady-state conditions are investigated. Formulation of the optical filter response is presented by considering with/without single and multiple Sagnac loop effects. Effects of the FORR parameters of filter response are studied and analyzed under different parametric conditions for the maximum transmission intensity. The simulation results show that the filter responses are affected strongly by the Sagnac loop and the FORR parameters. With the Sagnac effect, it is shown that full-width at half maximum (FWHM) would increase by increasing the phase difference Δϕ from 0 to 0.20 radian, beyond which it will start decreasing. The difference in FWHM value in this range of Δϕ variations is found to be about 3.77 nm. Between the first and the second resonances at wavelengths 1395 and 1538 nm, the free spectral range (FSR) is found to be 140 nm. In multiple loops effects, by increasing the number of loop turn N, the values of FSR would reduce. For Δϕ = 0.3 and N = 1, 2, 3, the values of FSR are obtained as 144, 74, 47 nm, respectively.

Electrostatically Tuned Optical Filters Based on Hybrid Plasmonic-Dielectric Thin Films for Hyperspectral Imaging

Hyperspectral imaging has a wide range of uses, from medical diagnostics to crop monitoring; however, conventional hyperspectral imaging systems are relatively slow, bulky, and rather costly. In this paper, we present an inexpensive, compact tunable optical filter for hyperspectral applications. The filter is based on a Fabry-Pérot interferometer utilizing hybrid metallic-dielectric mirrors and actuated using a MEMS electrostatic actuator. The optical filter is designed using the transfer matrix method; then, the results were verified by an electromagnetic wave simulator. The actuator is based on a ring-shaped parallel plate capacitor and is designed using COMSOL Multiphysics. An actuation displacement of 170 nm was used, which is the required distance to tune the filter over the whole visible range (400–700 nm). There are two designs proposed for the optical filter: the first was optimized to provide maximum transmission and the other is optimized to have minimum full-width-half-maximum (FWHM) value. The first design has a maximum transmission percentage of 94.45% and a minimum transmission of 86.34%; while the minimum FWHM design had an average FWHM value of 7.267 nm. The results showed improvements over the current commercial filters both in transmission and in bandwidth.

Bandwidth-tunable optical filter based on microring resonator and MZI with Fano resonance

A bandwidth-tunable optical filter is fabricated by combining Mach–Zehnder interferometer (MZI) and microring resonator. Both bandwidth red-shift and blue-shift are observed in the experiment. The bandwidth can be tuned from 0.46 to 3.09 nm by controlling two phase shifters. The device also shows an extinction ratio higher than 25 dB. Potential applications are integrated optical signal processing such as reconfigurable filtering and channel selecting in wavelength division multiplexer.

Tunable optical filter based on one-dimensional periodic structure composed of SiO2 and anisotropic metamaterial (AMM) with a liquid crystal defect layer sandwiched by two SiO2

This paper reports the tunable transmission properties of asymmetric one-dimensional periodic structure (1DPS) composed of SiO2 and anisotropic metamaterial (AMM) layers with defect of liquid crystal (LC) sandwiched by two SiO2 layers, i.e., (SiO[Formula: see text]AMM)[Formula: see text]SiO[Formula: see text]LC[Formula: see text]SiO[Formula: see text](SiO[Formula: see text]AMM)3 using the transfer matrix method (TMM). We have studied the optical properties of the periodic structure (SiO[Formula: see text]AMM)3 [Formula: see text]SiO[Formula: see text]LC[Formula: see text]SiO[Formula: see text](SiO[Formula: see text]AMM)3 with a different incident angle of the electromagnetic wave for particular director angle of LC molecules. The tunability of the transmission property of the considered 1DPS shows that the transmittance depends upon the orientation of LC molecules. Such an asymmetric periodic structure (1DPS) composed of SiO2 and AMM with a defect of LC sandwiched by two SiO2 layers, (SiO2 [Formula: see text]AMM)[Formula: see text]SiO[Formula: see text]LC[Formula: see text]SiO[Formula: see text](SiO[Formula: see text]AMM)3, may be used as a tunable optical filter and bi-stable device.