A Study of Fan-Out Periodic Domain Inversion in Lithium Niobate for Second Harmonic Generation

• Main Authors: Chih-Wei Huang, 黃志偉
• Other Authors: Way-Seen Wang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/71842417884830422296

碩士 === 國立臺灣大學 === 電機工程學研究所 === 88 === The current demands of blue light sources are emerging for the academic and industrial applications. However, short wavelength industrial grade lasers cannot be easily fabricated with the existing semiconductor laser techniques. Using second harmonic generation, sum frequency generation or difference frequency generation on nonlinear crystals, it is possible to produce lasers covering the whole spectral range with the current availability of limited laser sources. With quasi-phase matching technique, it only requires the coupling of light to the nonlinear crystal which has periodic domain inversion grating and waveguide structures, and a subsequently efficient double frequency generation of light can be made. As we enhance the optic field by focusing light into the waveguides, the nonlinear phenomena will be more pronounced. We introduce periodic domain inversion via diffusion of titanium, in combination with nickel-indiffused and annealed proton exchange waveguides, and fan-out design of grating. Aimed at a fundamental pump frequency of 980nm diode laser, we successfully produced devices of second harmonic generation for blue light. The calculated normalized conversion efficiency is about 2.6%/W. We also discuss the compatibility of the fabrication processes of waveguide and periodic domain inversion, and prove the processes would not destroy the structure of periodic domain inversion.