Single and multi-stage high power optical isolators using a single polarizing element

Abstract

An optical isolator for generally collimated laser radiation includes a single polarizing element, at least one Faraday optical element, at least one reciprocal polarization altering optical element disposed at the single polarizing element, at least one reflective optical element for reflecting radiation to provide an even number of passes through the at least one Faraday optical element, and a magnetic structure. The magnetic structure is capable of generating a magnetic field within the at least one Faraday optical element that is generally aligned with the even number of passes along a beam propagation axis. The optical isolator is configured to receive generally collimated laser radiation, which passes through the single polarizing element and the at least one reciprocal polarization altering optical element and which makes at least two passes through the at least one Faraday optical element, whereby generally collimated laser radiation is output from the optical isolator.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]The present application claims the filing benefits of U.S. provisional application Ser. No. 62 / 269,349, filed Dec. 18, 2015, which is hereby incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates to high power optical isolators and more particularly to high power single and multi-stage polarization maintaining [“PM”] and polarization insensitive [“PI”] optical isolators.BACKGROUND OF THE INVENTION[0003]Optical isolators are routinely used to decouple a laser oscillator from downstream laser amplifier noise radiation and / or target reflections. Optical isolators are typically comprised of a Faraday rotator surrounded by polarizers that are aligned with the input and output linear polarization states. A Faraday rotator is typically comprised of a non-reciprocal, optical element in a strong magnetic field that is co-axially aligned with the laser radiation so that the plane of polarization is...

AI Technical Summary

Benefits of technology

[0011]The present invention provides PM and PI multi-pass isolator forms that are simple to align, have few optical parts to assemble and work well with scalable beam diameters large enough to prevent optical damage in the optical elements of the isolator when used with high peak and average power laser sources. The present invention relates to high peak and average power optical isolators and more particularly to high power single and multi-stage polarization maintaining [“PM”] and polarization insensitive [“PI”] optical isolators with improved size, improved alignment simplicity, reduced parts count, and reduced cost.

Problems solved by technology

This results in reverse propagating radiation to experience high transmission losses while allowing forward propagating radiation to experience low transmission losses.

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