BCl3plasma for reactive ion etching of GaAs and GaSb structure have been examined as a function process parameters: RF power, BCl3pressure and gas additive (Ar, N2). High rate etching of GaSb from 110 nm/min. to 1600 nm/min. is well controlled by RF power, BCl3pressure and it can be increased up to 2 times by an additional Microwave Downstream (MVDS). Smooth etched surface morphologies were obtained at low and medium RF power densities. Anisotropy of etching was evaluated by measurements of sidewall profiles. Highly anisotropic etching and smooth etched surfaces were observed at optimum conditions (RIE 25 W, BCl36 Pa). Operating under these conditions the mesa structures of the detectors and of the double ridge waveguide lasers are fabricated by photolithography. An circular grating for high-efficiency Surface Emitting Lasers is presented to.