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Chapter I Brief Introduction...
effective nonlinear coefficient (deff), as given by equation (1.8), in general,
higher the power density, longer the crystal length, larger the nonlinear
coefficients and smaller the phase mismatching will result higher conversion
efficiency. However, there are some limitations coming from nonlinear crystals
and lasers used , for example, the deff is determined by the nonlinear crystal
itself and the input power density has to be lower than the damage threshold
of crystal.
1.4 Some NLO Crystal Parameters
For selecting crystals for different applications, certain crystal
parameters are important to consider along with the laser parameters. Table
(1.1) lists various laser and crystal parameters for selecting proper NLO
crystals. Various NLO parameters are discussed in detail by Adhav [21].
Table :1.1 Different Laser and Crystal Parameters required for NLO.
Crystal Acceptance
Laser Parameters Crystal Parameters
NLO Process Phase-Matching Type and Angle
Power or Energy Damage Threshold, D eff
Divergence Acceptance
Bandwidth Spectral Acceptance
Beam Size Crystal Size, Walk-off Angle
Pulse Width Group Velocity Mismatching
Repetition Rate Damage Threshold
Environment Temperature Acceptance, Moisture
If a laser light propagates in the direction with angle Δθ to phase
matching direction, the conversion efficiency will reduce dramatically. One
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