# Integrated polarizers based on graphene oxide in waveguides and ring resonators

## TL;DR

This paper demonstrates integrated waveguide polarizers and micro-ring resonators with graphene oxide films, achieving high polarization selectivity and providing insights into material effects and device performance.

## Contribution

It introduces a layer-by-layer GO coating method for integrated photonic devices, enabling precise control and high polarization selectivity in waveguides and resonators.

## Key findings

- Achieved ~53.8 dB polarization dependent loss with patterned GO films.
- Demonstrated 8.3 dB polarization extinction ratio in micro-ring resonators.
- Identified material loss anisotropy and mode overlap as key performance factors.

## Abstract

Integrated waveguide polarizers and polarization-selective micro-ring resonators (MRRs) incorporated with graphene oxide (GO) films are experimentally demonstrated. CMOS-compatible doped silica waveguides and MRRs with both uniformly coated and patterned GO films are fabricated based on a large-area, transfer-free, layer-by-layer GO coating method that yields precise control of the film thickness. Photolithography and lift-off processes are used to achieve photolithographic patterning of GO films with precise control of the placement and coating length. Detailed measurements are performed to characterize the performance of the devices versus GO film thickness and coating length as a function of polarization, wavelength and power. A high polarization dependent loss of ~53.8 dB is achieved for the waveguide coated with 2-mm-long patterned GO films. It is found that intrinsic film material loss anisotropy dominates the performance for less than 20 layers whereas polarization dependent mode overlap dominates for thicker layers. For the MRRs, the GO coating length is reduced to 50 microns, yielding a ~ 8.3-dB polarization extinction ratio between TE and TM resonances. These results offer interesting physical insights and trends of the layered GO films and demonstrate the effectiveness of introducing GO films into photonic integrated devices to realize high-performance polarization selective components.

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Source: https://tomesphere.com/paper/1907.06861