Model and Simulation of a Tunable Birefringent Fiber Using Capillaries Filled with Liquid Ethanol for Magnetic Quasiphase Matching In-Fiber Isolator

Clint Zeringue,Gerald T Moore

doi:10.1155/2010/586986

Abstract

A technique to tune a magnetic quasi-phase matching in-fiber isolator through the application of stress induced by two mutually orthogonal capillary tubes filled with liquid ethanol is investigated numerically. The results show that it is possible to “tune” the birefringence in these fibers over a limited range depending on the temperature at which the ethanol is loaded into the capillaries. Over this tuning range, the thermal sensitivity of the birefringence is an order-of-magnitude lower than conventional fibers, making this technique well suited for magnetic quasi-phase matching.

Highlights

Optical isolators play a critical role in the fabrication of highpower fiber amplifiers
Polarization independent isolators consist of an input birefringent wedge, a Faraday rotator, and an output birefringent wedge oriented at 45◦ to the first
The approach was to minimize the sensitivity in the birefringence with respect to operating temperatures near room temperature while maximizing the sensitivity in the beat length with respect to loading temperature

Summary

Introduction

Optical isolators play a critical role in the fabrication of highpower fiber amplifiers. Their purpose is to protect optical sources from light traveling in the backward direction which can cause damage to the optical source and instabilities in the output spectra. Optical isolators come in two flavors: polarization-dependent and polarization-independent. The polarization dependent isolator consists of an input polarizer, a Faraday rotator, and an output polarizer. Polarization independent isolators consist of an input birefringent wedge (with its ordinary polarization direction vertical and its extraordinary polarization direction horizontal), a Faraday rotator, and an output birefringent wedge oriented at 45◦ to the first. The birefringent crystals and Faraday rotator should have low absorption coefficients at the wavelengths of interests, low nonlinear refractive indices, and high damage thresholds. The Faraday rotator should have a high Verdet constant to achieve the highest degree of rotation with minimal length to prevent self-focusing inside the material and other thermal effects, as well as nonreciprocal nonlinear polarization coupling at high power

Methods

Results

Conclusion