Ultracompact and fabrication-tolerant integrated polarization splitter

Abstract

Design and fabrication of a 2×2 two-mode interference (TMI) coupler based on-chip polarization splitter is presented. By changing the angle between the access waveguides, one can tune the effective TMI length for the mode with less optical confinement (transverse magnetic, TM) to coincide with the target TMI length for a desired transmission of the mode with higher optical confinement (transverse electric, TE). The fabricated 0.94 μm long 2×2 TMI splits the input power into TM (bar) and TE (cross) outputs with splitting ratio over 15 dB over 50 nm bandwidth. Fabrication tolerance analysis shows that the device is tolerant to fabrication errors as large as 60 nm.

Low-Loss and Broadband <inline-formula> <tex-math notation="LaTeX">$2 \times 2$ </tex-math> </inline-formula> Polarization Beam Splitter Based on Silicon Nitride Platform

“…On the silicon-on-insulator (SOI) platform, directional coupler [15][16][17] and multimode interferometer (MMI) [18,19] based PBSs with low loss, high extinction ratio (ER) and wide bandwidth have been demonstrated. However, these kinds of devices become considerably long on the SiN platform due to the reduction in ∆neff between the fundamental TE and TM polarizations.…”

A compact plasmonic MOS-based 2×2 electro-optic switch

“…An important building block for network-on-chip architectures is the 2×2 crossbar switch, a device with two inputs and outputs whereas the optical routing is controlled by an electrical gate. A variety of photonic switches have been investigate such as those based on directional couplers (DC) [2][3][4], multimode interference (MMI) [5,6], ring resonators, Mach-Zehnder interferometers (MZI) [7,8] and photonic-crystal-based (PhC) structures [9][10][11]. While these approaches are able to reduce the footprint into the ten's of micrometer scale for instance by deploying high-Q ring resonators, they introduce other limitations relating to bandwidths (spectrally and temporally) and demand tighter fabrication tolerances for mode-coupled devices [12,13].…”

CMOS-compatible and fabrication-tolerant MMI-based polarization beam splitter

“…Recently, silicon-on-insulator (SOI) has become an attractive candidate material to realize dense PICs for its compatibility with complementary metal oxide semiconductor (CMOS) technology and its high refractive index contrast. The MMI PBSs based on SOI have been demonstrated [9][10][11], which utilize air as the top cladding layer. However, this lack of solid cladding layer makes the device incompatible with most metal back-end-of-line (BEOL) processes, and thus greatly complicates the integration with other SOI photonic devices.…”

“…However, this lack of solid cladding layer makes the device incompatible with most metal back-end-of-line (BEOL) processes, and thus greatly complicates the integration with other SOI photonic devices. Besides, the PBS [11] is extremely sensitive to the angle (7.41) between the access waveguides.…”