On-chip multifunctional polarizer based on phase change material.

Abstract

Polarizers are used to eliminate the undesired polarization state and maintain the other one. The phase change material Ge2Sb2Se4Te1 (GSST) has been widely studied for providing reconfigurable function in optical systems. In this paper, based on a silicon waveguide embedded with a GSST, which is able to absorb light by taking advantage of the relatively large imaginary part of its refractive index in the crystalline state, a multifunctional polarizer with transverse electric (TE) and transverse magnetic (TM) passages has been designed. The interconversion between the two types of polarizers relies only on the state switching of GSST. The size of the device is 7.5µm∗4.3µm, and the simulation results showed that the extinction ratio of the TE-pass polarizer is 45.37dB and the insertion loss is 1.10dB at the wavelength of 1550nm, while the extinction ratio (ER) of the TM-pass polarizer is 20.09dB and the insertion loss (IL) is 1.35dB. For the TE-pass polarizer, a bandwidth broader than 200nm is achieved with ER>20dB and IL<2.0dB over the wavelength region from 1450 to 1650nm and for the TM-pass polarizer, ER>15dB and IL<1.5dB in the wavelength region from 1525 to 1600nm, with a bandwidth of approximately 75nm.