Quadratic spatial solitons generated in periodically poled lithium tantalite

Wenjun Liu,Gang Yang,Xiang Lin,Shengli Fan,Lihui Pang

doi:10.1117/1.oe.52.8.087103

Abstract

The properties of quadratic spatial solitons generated in periodically poled lithium tantalite in the femtosecond regime are investigated. By using only a fundamental frequency beam as the input to excite quadratic spatial solitons, single and spatially anisotropic multiple solitons are generated. Our experiments demonstrate that the number of solitons is dependent on the input power. In the experiment, beam narrowing occurs first, leading to single-soliton generation. The threshold for multiple solitons is around 1.5 mW. The number of solitons does not increase indefinitely with input power. Multiple soliton generation only occurs in the input power range of 1.5 to 6.3 mW. The number of solitons decreases to 1 when the input power is 6.3 mW. The temporal and spectral characteristics of the spatial solitons are measured by using the GRENOUILLE technique.

Highlights

With the development of high power ultrafast lasers, quadratic nonlinear crystals have become widely used in nonlinear optics, and the quadratic spatial soliton is one of the most intriguing nonlinear effects.[1,2,3,4,5,6,7,8,9,10] One of the unique features of quadratic solitons is that they consist of all of the beams strongly coupled together by the second-order nonlinearity
As long as the walk-off distance is less than the gain length, the fundamental and harmonic beams are locked in space and copropagate together as quadratic spatial solitons
A magnified image of the output beam at the exit surface of the periodically poled lithium tantalite (PPLT) crystal is recorded by a charge-coupled device (CCD) camera connected to a beam analyzer

Summary

Introduction

With the development of high power ultrafast lasers, quadratic nonlinear crystals have become widely used in nonlinear optics, and the quadratic spatial soliton is one of the most intriguing nonlinear effects.[1,2,3,4,5,6,7,8,9,10] One of the unique features of quadratic solitons is that they consist of all of the beams strongly coupled together by the second-order nonlinearity. Second-harmonic generation (SHG) processes can result in generation of quadratic spatial soliton. With their particlelike behavior in interactions and collisions, spatial solitons have the potential to be used for all-optical data processing, pattern recognition, and parallel information storage.[11,12,13]. The self-trapped soliton exists by virtue of the strong interaction and energy exchange between two or more beams with different frequencies. In SHG, it is common for the energy propagation directions of the fundamental and harmonic beams to be different. As long as the walk-off distance is less than the gain length, the fundamental and harmonic beams are locked in space and copropagate together as quadratic spatial solitons

Methods

Results

Conclusion