SPATIAL CONTROLLABILITY OF PERIODIC RIPPLE STRUCTURES GENERATED IN LASER ETCHING OF N-GAAS

Spatial controllability of periodic ripple structures was investigated in laser etching of n-GaAs. For single-beam etching and holographic etching with high ratios of average spacing of holographic grating to average spacing of ripple structures (LAMBDA(h)/LAMBDA(h)), ripple structures were observed. In particular, in p-polarization, spatial fluctuation was greater than that in s-polarization. This might occur because phase distortion cannot be eliminated by p-polarization beam irradiation. For holographic etching with small LAMBDA(h)/LAMBDA(r) ratios, ripple structures were changed into grating structures because these grating structures might be generated in phase with holographic gratings.