Broad Bandwidth Blue Laser Based on Quasi-Phase-Matched Periodically-Poled Lithium Tantalate
Date Issued
2010
Date
2010
Author(s)
Wu, Chien-Chih
Abstract
This thesis is composed of three parts：(1) the theory of quasi-phase- matching(QPM) and the QPM optical parametric oscillator(OPO), (2) the fabrication technique of one-dimensional periodically poled congruent grown lithium tantalite(LiTaO3) for cascade OPO-SHG 465nm blue laser chip, (3)the measurement and analysis of OPO-SHG blue light generators.
First of all, I will introduce the mechanism of nonlinear frequency conversion and QPM theory, and it’s application to the optical parametric and second harmonic generation. Using Sellmeier equation, I design the QPM period of periodically poled LiTaO3(PPLT) for the above application. By taking advantage of the nickel-diffusion assisted electric poling process, I fabricated 930nm OPO devices of 5um periodicity on 0.5mm- and 0.75mm-thick congruent LiTaO3 substratee. Using this method, cascaded OPO-SHG PPLT device with a chirp structure in SHG segment, composed of 3 periods separate period of 4.96um, 4.98um, and 5um. With this design, the output of blue light contains high conversion effiency and broad spectrum.
Using a 532nm, 5ns pulsewidth laser as the pump source, a 16mm long cascaded OPO-SHG chip in a concave laser cavity of 17mm length is shown to generate a 465nm blue laser. The spectrum is shown to have a 0.8nm bandwidth and an up-conversion effiency of 16% at 350mW green pump.
Subjects
broad spectrum
blue laser
lithium tantalate
Type
thesis
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