Squeezing in the sum and difference fields in second harmonic generation

In this article we show that, in intracavity second harmonic generation, a combined quadrature can be chosen which exhibits considerably more squeezing than the amplitude quadratures of the fundamental or second harmonic individually. We also investigate squeezing in single-pass travelling wave second harmonic generation, showing that previously published results are not accurate for arbitrary interaction length, with the behaviour obtained being qualitatively different. (C) 1999 Elsevier Science B.V. All rights reserved.