Loss-induced phase-sensitive spatial light modulator with a wide field of view

We investigate the feasibility of achieving practical phase modulation by changing only the absorption of the device. We present a spatial light modulator that consists of a three-mirror cavity with lossy slabs inserted between the mirrors. When only the absorption of these slabs is changed, this device can have a gradual change in phase, but no intensity modulation. Theoretical analysis by the use of numbers appropriate to multiple quantum wells shows that the total phase-tuning range can be as large as 2π with an absorption coefficient change of less than 9000 cm(-1); the length of each multiple-quantum-well slab is ~ 1.5 µm. This gives an expected 16° field of view with the nanosecond speed typical of semiconductors.