A nonlinear frequency conversion system includes a first element including a first medium configured to perform type II birefringent phase matching (BPM) of a pump beam to provide corresponding seed beams having at least first and second polarization states. A second element includes a second medium...http://www.google.de/patents/US7339722?utm_source=gb-gplus-sharePatent US7339722 - Hybrid nonlinear optical conversion and optical parametric oscillation
