2015年8月13日星期四

Quasi-phase matched broadband difference frequency generation in the mid-infrared region using total internal reflection in a tapered gallium arsenide (GaAs) slab

We developed an analytical model of a quasi-phase matched mid-infrared frequency converter which uses total internal reflection in an isotropic semi-conductor slab (GaAs) having tapered configuration. A computer aided simulation has been performed by adopting Difference Frequency Generation (DFG) with ppp polarization where the pump wave is of 4 μm and the signal bandwidth lies between 14-17 μm. The resultant 3 dB broadband output has a bandwidth of 523 nm centred at 15.423 μm and a peak conversion efficiency of 0.091% in a 30 mm long slab. Due consideration has been given to the effect of optical beam walk off on the frequency conversion process, and the losses due to absorption, Goos-Hänchen shift and surface roughness. We also analyse the impacts of the variations in tapering angle, temperature, angle of the front face, beam walk off tolerance and angle of refraction at the air-crystal interface inside the slab, on the performance of the frequency converter.

Keywords

  • Broadband
  • Isotropic semiconductors
  • Gallium Arsenide
  • Difference frequency generation
  • Total internal reflection quasi-phase matching
  • Goos-Hänchen shift
  • Optical beam walk-off.