Holographic injection locking of a broad area laser diode via a photorefractive thin-film device

P D Van Voorst,H L Offerhaus,M R De Wit,S Tay,K.-J Boller,J Thomas,N Peyghambarian

doi:10.1364/oe.15.017587

Abstract

We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time. A four-wave mixing setup is used to generate feedback for the broad area diode at the wavelength of the single frequency source (Ti:Sapphire laser) while the spatial distribution adapts to the preferred profile of the broad area diode. The result is an injection-locked broad area diode emitting with a linewidth comparable to the Ti:Sapphire laser.

Highlights

Broad area lasers (BALs) can produce output powers up to several Watts
We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time
Since holographic locking in different configurations can be used to improve the spatial beam quality besides the spectral quality, we believe it is useful to investigate alternative locking configurations

Summary

Introduction

Broad area lasers (BALs) can produce output powers up to several Watts. This high output power is achieved, at the cost of a poor spatial and spectral quality of the emitted radiation caused by the large gain area and wide output facet. BaTiO 3 is a delicate material and depolarization can occur due to mechanical stress, and operation or storage outside a limited temperature range It has a high refractive index of about 2.4 giving rise to parasitic effects due to crystal-internal reflections. This means that those parts of the beams that do not overlap have to travel significant distances through the the crystal as well, which can lead to the build-up of parasitic gratings [11] requiring additional suppression [5] These disadvantages motivated us to investigate alternative photorefractive materials for their use in holographic injection locking. As the signatures of locking we find that the BAL emits at a single-frequency concomitant with a temporal stabilization of the BAL output into its self-preferred, spatial mode pattern

Experiment

Results

Summary and Conclusions