# Low power (mW) nonlinearities of polarization maintaining fibers

## TL;DR

This paper investigates the nonlinear polarization effects in polarization maintaining fibers at low power levels, revealing potential applications in sensing, power control, and stabilization.

## Contribution

It demonstrates that even at low milliwatt power levels, PM fibers exhibit nonlinear transmission effects useful for various optical applications.

## Key findings

- Nonlinear transmission observed at power levels below a few milliwatts.
- Monitoring polarization enables new sensing and stabilization methods.
- Time constants of nonlinear effects are in the microsecond range.

## Abstract

Polarization maintaining (PM) fibers are meant to maintain linear polarization along a preferred axis. A PM fiber can be seen as the fiber version of a very high order waveplate, designed with different refractive indices along two orthogonal axes. It is shown that monitoring the polarization of initially circularly polarized light sent through a PM fiber, leads not only to new sensing methods, but also to power control, saturable absorption, and optical path stabilization. Even at peak power levels not exceeding a few mW, nonlinear transmission is detected, with time constants in the microsecond range.