1. Apparatus for frequency-doubling optical radiation, the apparatus comprising:
a) an optically nonlinear medium that receives a first beam of optical radiation having a first frequency, wherein the first
beam makes N passes through the nonlinear medium, where N is an integer ≧2, to thereby generate a second beam having a second
frequency substantially equal to twice the first frequency; and
b) a telescope subassembly having an ABCD matrix with matrix coefficients substantially A=−1, B has any real value, substantially
C=0 and substantially D=−1, for receiving and coupling the first and second beams, emitted from the nonlinear medium after
a pass number J, back into the nonlinear medium for a pass number J+1, where 1≤J<N, wherein the second beam issues from the
telescope subassembly.
|