A new reconfigurable cascadable all-optical on-
chip device is presented. The gate operates by combining the
Vernier effect with a novel effect, the
gain-index lever, to help shift the dominant lasing mode from a mode where the
laser light is output at one
facet to a mode where it is output at the other
facet. Since the
laser remains above threshold, the speed of the gate for logic operations as well as for
reprogramming the function of the gate is primarily limited to the small
signal optical modulation speed of the
laser, which can be on the order of up to about tens of GHz. The gate can be rapidly and repeatedly reprogrammed to perform any of the basic digital logic operations by using an appropriate analog optical or electrical
signal at the gate selection port. Other all-optical functionality includes
wavelength conversion,
signal duplication, threshold switching,
analog to digital conversion, digital to analog conversion,
signal routing, and environment sensing. Since each gate can perform different operations, the functionality of such a cascaded circuit grows exponentially.