Compact and phase-error-robust multilayered AWG-based wavelength selective switch driven by a single LCOS

Abstract

A novel liquid crystal on silicon (LCOS)-based wavelength selective switch (WSS) is proposed, fabricated, and demonstrated. It employs a multilayered arrayed waveguide grating (AWG) as a wavelength multiplex/demultiplexer. The LCOS deflects spectrally decomposed beams channel by channel and switches them to desired waveguide layers of the multilayered AWG. In order to obtain the multilayered AWG with high yield, phase errors of the AWG is externally compensated for by an additional phase modulation with the LCOS. This additional phase modulation is applied to the equivalent image of the facet of the AWG, which is projected by a relay lens. In our previously-reported WSS configuration, somewhat large footprint and increased cost were the drawbacks, since two LCOSs were required: one LCOS was driven for the inter-port switching operation, and the other was for the phase-error compensation. In the newly proposed configuration, on the other hand, both switching and compensation operations are performed using a single LCOS. This reduction of the component count is realized by introducing the folded configuration with a reflector. The volume of the WSS optics is 80 × 100 × 60 mm³, which is approximately 40% smaller than the previous configuration. The polarization-dependent loss and inter-channel crosstalk are less than 1.5 dB and -21.0 dB, respectively. An error-free transmission of 40-Gbit/s NRZ-OOK signal through the WSS is successfully demonstrated.

Programmable High-Resolution Spectral Processor in C-band Enabled by Low-Cost Compact Light Paths

“…Currently, the spatial light modulator (SLM) utilizing LCoS (LCoS-SLM) is the most competing technique adopted in the design of multiple port WSSs [10][11][12][13][14]. LCoS device combing with gratings can be further developed as programmable PSP for processing optical spectrum resources [15].…”

Silicon monolithic wavelength selective switch utilizing arrayed waveguide gratings and Bragg grating filters

“…However, silicon AWGs are difficult to put into practical use because of high crosstalk due to phase errors caused by manufacturing errors [15] [16]. Free-space optics type WSSs use MEMS mirrors [17] [18][19] [20] or LCOS [21][22][23] [24] for switching. Although free-space optic type WSSs have low loss and crosstalk and can be configured with multiple ports and channels, the switching speed with MEMS mirrors and LCOS is slow (a few milliseconds).…”

Asymmetric Optical Wavelength Switch Based on LCoS-SLM for Edge Node of Optical Access Network

“…Several technologies, including thermo-optic waveguide switches [6], 1D/2D MEMS [7][8], and polarization-modulated liquid crystal (LC) switches [9], have been developed for ROADM applications in an optical core transport network. Liquid Crystal on Silicon (LCoS) based optical wavelength switches were considered the most key-enabling technology in future optical networks [10][11]. Moreover, hologram beam steering switches based on LCoS spatial light modulator (SLM) have been reported as a promising optical switch technology for edge node application [12].…”