| 摘要 |
According to one embodiment of the invention, improved multipass second harmonic generation (SHG) is provided by the use of an inverting, self-imaging telescope. This embodiment ensures parallelism of all passes of all beams within the nonlinear medium. According to another embodiment of the invention, improved multipass SHG is provided by the use of a wedged phasor. This arrangement provides a simple adjustment of the relative phase of the pump beam and second harmonic beam between passes. According to a further embodiment of the invention, improved multipass SHG is provided by the use of an inverting self-imaging telescope in combination with a wedged phasor. This arrangement provides a simple adjustment of the relative phase of the pump beam and second harmonic beam between passes, and ensures parallelism of all passes of all beams within the nonlinear medium. This arrangement also allows corresponding passes of the pump beam and second harmonic beam to be made collinear within the nonlinear medium. A further embodiment of the invention comprises an OPO having at least one phasor for receiving and adjusting the phase of the one or more beams resonating within the optical cavity which forms part of the OPO. A further OPO embodiment includes first and second telescope assemblies, the optical cavity, phasor and nonlinear medium components of the OPO being situated between the two telescopes.
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