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 l ight 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 in tensity modulation. Theoretical analysis by the use of numbers appropr iate to multiple quantum wells shows that the total phase-tuning range can be as large as 2pi with an absorption coefficient change of less than 9000 cm-1; the length of each multiple-quantum-well slab is appro ximately 1.5 mum. This gives an expected 16-degrees field of view with the nanosecond speed typical of semiconductors.