Please advise me more ... I understand BBO is one of those up down conversion materials with efficiency in very low % ranges.
I am scientist worked on Quantum Optics research works. May you suggest if I may have access of very high efficiency (e.g. > 95% conversion rate) nonlinear crystals with very high up or down frequency conversions (e.g. SPDC) for RED or GREEN Laser sources in my Lab?
this is idea not exactly right, the frequency conversion efficiency no only depend on the types materials crystal but also depend on several parameters such as the wavelength, dimensions of the crystal as well as intensity or the powers of the incident laser...,
Dear Mickey,
If you means physical efficiency it depends upon from the second order nonlinearity which are growing with main frequency while SHG power may decreasing if it is approaching to the nearest absorption band of crystal.
Technical efficiency depends on length of the nonlinear crystal in the phasing direction. This direction is also frequency dependent and very strong. Only the nonlinear crystals with 90-grade phasing do not have similar frequency dependence. If You will have choose nonlinear crystal with taking into account this details You get high efficiency of SHG. 90% efficiency of SHG has been achieved by the so called intracavity location of nonlinear crystal, but this way is connected with application cavity mirrors with the peculiar frequency reflection.
As well as, the phase matching conditions is very important factor.
The SHG conversion efficiency is determined by parameters related to the pump source, such as power density, beam divergence, and spectral linewidth, and to the harmonic generator, such as nonlinear coefficient, crystal length, angular and thermal deviation from the optimum operating point, absorption, and inhomogeneities in the crystal.
Dear Eugene and Raad,
Thanks a lot for both of your such good suggestion and teaching to me. Will keep me learning more ...
Nanophotonic PPLN waveguide with required phase matching condition for your nonlinear process (e.g. SHG or SFG). The normalized efficiency could be as high as 2,000~10,000 % W-1cm-2. This means, in principle, you could obtain near 100% conversion with few tens of milli-watt pump power for a centimeter long nanophotonic PPLN waveguide.
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