Laser-written polarizing directional coupler with reduced interaction length

TL;DR

This paper presents a novel femtosecond laser written polarizing directional coupler that significantly reduces device size by exploiting stress-induced anisotropy, advancing integrated photonics with polarization control.

Contribution

The study introduces a stress-induced anisotropy method to miniaturize femtosecond laser written polarizing directional couplers, overcoming previous size limitations.

Findings

Reduced the size of polarizing directional couplers by nearly an order of magnitude.

Demonstrated stress-induced anisotropy as an effective approach for device miniaturization.

Provided detailed analysis of waveguide interactions in close proximity.

Abstract

Integrated optical devices are becoming a common tool in modern optical science and engineering. This devices should be designed to allow for precise control and manipulation of light. The femtosecond laser written (FSLW) photonic chips have proven to cope with the most current demands of integrated photonics. However, up to date the polarization degree of freedom has rarely been exploited in experiments performed on the FSLW integrated platform. The main obstacle is an intrinsically low anisotropy of laser written waveguides, preventing the design of polarizing integrated devices with small footprint. In this Letter we demonstrate the approach based on stress-induced anisotropy allowing us to decrease the size of polarizing directional couplers fabricated with the FSLW technology by almost an order of magnitude. We provide an accurate account for the effects emerging in waveguides written in a close proximity to each over.