Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides

Abstract

Abstract:A new way to make broadband polarizers on silicon-on-insulator (SOI) waveguides is proposed, analyzed and characterized. The characteristics of the eigenmodes in a shallowly-etched SOI ridge optical waveguide are analyzed by using a full-vectorial finite-different method (FV-FDM) mode solver. The theoretical calculation shows that the loss of TE fundamental mode could be made very low while at the same time the TM fundamental mode has very large leakage loss, which is strongly dependent on the trench width. The leakage loss of the TM fundamental mode changes quasi-periodically as the trench width w tr varies. The formula of the period ∆w tr is given. By utilizing the huge polarization dependent loss of this kind of waveguide, a compact and simple optical polarizer based on a straight waveguide was demonstrated. The polarizer is fabricated on a 700nm-thick SOI wafer and then characterized by using a free-space optical system. The measured extinction ratio is as high as 25dB over a 100nm wavelength range for a 1mm-long polarizer.

TE-Pass Polarizer With Cylinder Array Inserted in Buffer Layer of Silica-on-Silicon Waveguide

“…Where β im is the imaginary part of the propagation constant and l 0 is the propagation distance [13]. By optimally designing the parameters of the CABL-WG, the leakage loss of the TM fundamental mode is higher than that of the TE fundamental mode, which can obtain TE-pass single polarization waveguide.…”

Broadband and Compact TE-Pass Polarizer Based on Hybrid Plasmonic Grating on LNOI Platform

“…The basic principle to design a polarizer is to distinguish one polarization of propagation loss from others. Conventionally, the dielectric-based polarizer has been developed to achieve high extinction ratio (ER) and low insertion loss (IL) [4]- [8]. These polarizers usually utilize shallowetched waveguide or subwavelength grating waveguide to accomplish large leakage loss.…”

Si-core photonic crystal fiber transverse-electric pass polarizer

“…Therefore, it is mandatory to design compact polarizers that can be integrated on PIC. This gave rise to silicon-on-insulator (SOI) polarizers [6]. SOI devices have advantages in terms of low cost and high compatibility with CMOS as well as silicon sources and detectors [7].…”

“…Many SOI-based transverse electric (TE)/transverse magnetic (TM)-pass polarizers are available in literature. Dai et al have proposed a TE-pass polarizer with a device length of 1 mm [6]. Alam et al have introduced a compact hybrid TM-pass polarizer for SOI platforms [8].…”