Abstract

Nonlinear optical effects based on birefringent phase matching and quasi-phase-matching (QPM) are an inherent part of contemporary photonics. Among the widely used nonlinear optical materials, numbering more than 80 compounds, only three (KTP, LN, LT) are suitable for creating commercially available periodically poled [1] (PP) structures. A number of approaches were used to create conditions for QPM in other materials. In [2], and [3] it was realized in Brewster-angle-stacked wafers (5 plates), made of GaAs and CdTe isotropic crystals. In [4] the QPM conditions were created in chalcogenide crystals by using specific packing defects-“twins”. Attempts were made to create a tight stack of multiple, bonded-together crystalline quartz plates [5]. But these methods did not receive further development. Here we propose a concept based on multiple passes of interacting beams through the same nonlinear crystal element placed inside a quasi-waveguide or multi-pass cell.

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