| Summary: | 碩士 === 淡江大學 === 物理學系 === 85 === The major purpose of this thesis is to investigate the
principle and effects of second-order nonlinear optical
frequency conversion, compare between different types of phase
matching methods, and produce tunable coherent deep ultraviolet(
UV) light by sum-frequency generation (SFG). In the theoretical
part, the effects of frequency mixing of optical waves in
nonlinear media are reviewed, and some basics of uniaxial and
biaxial crystals and of β-barium borate(BBO) crystals are
discussed. According to thn-縱lready known optical
characteristics of BBO, the phase matching angles for parametric
conversion and SFG in BBO are calculated; the walk off of the
sum-fr?簇ncy beam in BBO is also discussed. In the
experimental part, we used the third harmonic(TH) of a
nanosecond pulsed Nd:YAG laser to pump a BBO based optical
parametric oscillator (OPO) which provides a wavelength tuning
range from 450 nm to 690 nm for the signal wave and from 730 nm
to about 1.7 mm for idler wave. We used the signal wave (478-650
nm) and the residual pump beam of the OPO as the input beams to
perform SFG in BBO crystals, and thus, tunable coherent deep UV
output from 203.6 nm to 229.5 nm can be obtained. The average
SFG conversion efficiency is about 15% and the average energy of
deep UV output is about 8mJ/pulse. We also find that the SFG
conversion efficiency depends mainly on the intensity, beam
divergence, beam quality, and the degree of phase matching of
the interacting beams. The study shows that the SFG of the OPO
output and the TH beam of the Nd:YAG laser can be very efficient
for producing tunable deep UV light. The SFG system is all-
solid-state and is easy to operate.
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