Highly efficient broadband second harmonic generation in a tapered zinc telluride slab using total internal reflection fractional quasi phase matching

Abstract

We analytically describe broadband second-harmonic generation in a tapered zinc telluride (ZnTe) slab using total internal reflection fractional quasi-phase matching. Refractive index of ZnTe shows minimum deviation over a wide wavelength range resulting in increased coherence length which leads to fractional quasi-phase matching scenario, ensuring highly efficient second harmonic output. The simulated results, considering absorption and reflection losses, indicate 3dB bandwidth of 192.5nm, centered at 8.583μm, with conversion efficiency as high as 19.6% in a 30mm ZnTe slab. The effects of variations in incident angle at air–material interface, length and tapering angle of the slab have also been analyzed.