Patent ID: 7557368
Filing Date: 2009-07-07
Classification: B82Y,H01L

Abstract:
1. A method for detecting a light signal of a predetermined wavelength by two photon absorption using an optically pumped photodetector, the method comprising: providing the detector in the form of a resonator adapted to resonate in response to the light signal of the predetermined wavelength, the resonator having a plurality of spaced apart active semiconductor regions at locations substantially corresponding to anti-nodes of a resonating electromagnetic field, each active region defining a conduction band and at least one valence band, the conduction band defining with the corresponding valence band closest thereto an energy bandgap, selecting the material of the active regions so that the energy bandgap of each active region is such that the photon energy of the light signal of the predetermined wavelength is less than half of the energy gap of the bandgap, pumping the active regions with a pump light beam, the photon energy of which is not less than the energy gap of the band gap of each active region less the photon energy of the light signal of the predetermined wavelength, so that when the light signal of the predetermined wavelength is received simultaneously with the pump light beam a photon is absorbed by each active region from each of the light signal and the pump light beam to transfer an electron across the energy bandgap from the valence band to the conduction band of the corresponding active region, directing the light signal into the active regions, and monitoring the voltage across the active regions for detecting a change in voltage indicative of the light signal being of a predetermined wavelength.