Mirrorless optical parametric oscillators with stitching faults: Backward downconversion efficiency and coherence gain versus stochastic pump bandwidth

Description

Parametric downconversion in submicronic periodically poled (PP) quadratic materials allows the generation of signal and idler waves in opposite directions. The distributed feedback mechanism enables a backward mirrorless optical parametric oscillator (BMOPO), which has been experimentally realized using a periodically-poled KTP crystal with 800 nm periodicity. A remarkable spectral property of the BMOPO is that the bandwidth of the forward co-propagating wave is comparable to the pump bandwidth, whereas that of the backward wave is typically several orders of magnitude narrower. In the backward idler configuration realized in PPKTP the backward idler exhibits a coherence gain of two orders of magnitude. In this paper we will consider the backward signal configuration, where the effect of coherence enhancement of the backward signal wave is especially pronounced for exact group velocity matching of the co-propagating pump and idler waves.

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