Optical frequency conversion in quasi-phase-matched stacks of nonlinear crystals

The paper presents a quantitative theory of nonlinear frequency conversion in stacks of crystals in which the phase mismatch due to dispersion is compensated by changing the sign of the nonlinear coupling coefficient in successive crystals. The effects of systematic and random departures in crystal lengths are studied with emphasis on the evolution of the relative phase. It is shown that with the appropriate choice of the signs of the nonlinear coupling coefficient in various crystals, high efficiency frequency conversion should be possible using almost any sufficiently large set of nonlinear crystals. In addition, the theory of second harmonic generation in periodic stacks and in rotating twinned crystals of zinc-blend structure is described.