Wavelength dependence of the single pulse femtosecond laser ablation threshold of indium phosphide in the 400–2050nm range

We present single pulse femtosecond laser ablation threshold measurements of InP obtained by optical, scanning electron, and atomic force microscopy. The experiments were conducted with laser pulses 65–175fs in duration, in the wavelength range from 400 to 2050nm, covering the photon energy region above and below the bandgap of InP. The ablation thresholds determined from depth and volume measurements varied from 87mJ/cm2 at 400nm to 250mJ/cm2 at 2050nm. In addition, crater depths and volumes were measured over a range of laser fluences extending well above the ablation threshold.