Laser-induced etching of InP using two laser frequencies simultaneously

Two different lasers were used simultaneously to etch sinusoidal gratings on InP surfaces employing a thin-film cell configuration under external biasing, in which current was allowed to flow. Irrespective of the laser frequency, large pitch gratings etch faster than small ones when each single grating is etched separately. However, when two gratings are superimposed on each other these characteristics are changed. Also, there is a degradation in the etched profile after prolonged exposure time. This is more pronounced for relatively large pitches than for small pitches. We suggest that the reaction products, the oxide layer, regulate the reaction process in a reverse biased cell.