| Summary: | 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.
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