Open AccessInvestigation of thermally-induced phase mismatching in continuous-wave second harmonic generation: a theoretical model
Author(s) -
Mohammad Sabaeian,
Laleh Mousave,
Hamid Nadgaran
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.018732
Subject(s) - second harmonic generation , optics , materials science , refractive index , thermal , crystal (programming language) , energy conversion efficiency , temperature gradient , nonlinear optics , continuous wave , physics , optoelectronics , thermodynamics , laser , quantum mechanics , computer science , programming language
A fraction of the fundamental beam energy deposited into nonlinear crystals to generate second harmonic waves (SHW) causes a temperature gradient within the crystal. This temperature inhomogeneity can alter the refractive index of the medium leading to a well-known effect called thermal dispersion. Therefore, the generated SHW suffers from thermal lensing and a longitudinal thermal phase mismatching. In this work by coupling the heat equation with second harmonic generation (SHG) formalism applied to type-II configuration along with walk-off effect, we investigate the continuous wave (CW) SHW beam profile and conversion efficiency when a non-linear KTP crystal is under induced thermal load. We have demonstrated for average and high powers, the thermal de-phasing lead to considerable reduction in SHG compared to an ideal case in which induced heat is neglected.