Design of a large bandwidth 2 × 2 interferometric switching cell based on a sub-wavelength grating

Abstract

In the last few decades, increasing research effort has focused on the design of telecommunication payload systems with advanced features and lower costs in space applications. In this context, photonic solutions have already proven the potential to achieve additional functionalities, such as multiplexing or switching of RF or microwave signals, with consequent additional benefits in terms of size and mass reduction. In this paper, we report on the design of a 2 × 2 switching cell based on a thermo-optic interferometric configuration, whose key element is a sub-wavelength grating. We have theoretically demonstrated a broadband operation, with better performance in terms of operating wavelength range and compactness with respect to the existing interferometric cells. The switching cell shows a worst extinction ratio of about 13 dB, insertion loss of less than 2 dB, crosstalk of 12 dB, over a bandwidth of 150 nm, within a footprint as small as 240 µm × 9 µm. To demonstrate its potential use as a routing fabric in flexible telecommunication satellite payloads, as an example, the designed switching cell has been used as a building block of an 8 × 8 dilated Banyan matrix, where large bandwidth (150 nm), low crosstalk (−38 dB), small footprint (≈1620 µm × 576 µm) and relatively low power consumption (276 mW) have been achieved.

A 3-Dimensional Modelling of the Optical Switch Based on Guided Mode Resonances in Photonic Crystals

“…Considering the components of the PIC, an optical switch is an important element that can work analogous to the electronic transistor in the electronic integrated circuits. Therefore, utmost efforts are made to achieve the functions of optical switching element using the time domain [16] or frequency domain [17], with different topologies in the form of cross waveguide geometries [18], quantum dots [19], optoelectronic hybrid devices [20], ring resonators [21], combined configurations of thermodynamics and optical components [22] and utilization of transparent and active materials [23,24], with it desired working and implementation in the optical circuits. A 2D-FDTD design of an optical switch is investigated in [25], by means of the phenomenon of GMR with varying radius cavity implemented at the start of the PhC-mesh.…”

Range-Gated LIDAR Utilizing a LiNbO3 (LN) Crystal as an Optical Switch

“…In 2021, Giuseppe Brunetti et al from Italy designed a large-bandwidth 2 × 2 interferometric switching cell. The photonic switch they designed showed a worst-case extinction ratio of approximately 13 dB, insertion loss of less than 2 dB, and crosstalk of 12 dB over a broad bandwidth of 150 nm [25]. In 2023, Jie Tang et al from China designed a LNOI-based high-speed electro-optical switch.…”

An Optimization Framework for Silicon Photonic Evanescent-Field Biosensors Using Sub-Wavelength Gratings

“…SWG structures significantly extend the SiP design space by allowing for the fabrication of metamaterial anisotropic structures using standard single-etch CMOS-compatible techniques [ 42 ]. SWGs have been used to create photonic structures with tailored modal confinement, broadband behavior, dispersion control, and polarization management [ 42 , 43 ]. For example, the tailorability of modal confinement in SWGs has allowed for the design of ultralow loss waveguide crossings [ 41 ] and efficient couplers to interface on-chip waveguides with off-chip optical fibers [ 44 ].…”

“…The tailorable modal confinement and diffraction suppression afforded by SWGs have been employed to design ultracompact and broadband Y-branches [ 45 ] and adiabatic couplers [ 46 , 47 ]. Further, the controlled dispersion of SWGs has been leveraged to design broadband 2 × 2 interferometric switching cells [ 43 ] and broadband directional couplers [ 48 , 49 ]. Finally, SWG structures have been used to design optimized sensing waveguides [ 42 ].…”