PHOTODETECTOR WITH A RESONANT CAVITY

摘要

Described is a resonant-cavity p-i-n photodetector based on the reflection or transmission through a Fabry-Perot cavity incorporating non-epitaxial, amorphous layers with alternating refractive index difference electron-beam deposited on a light-gathering side of a commercially available photodetector. The materials of the Fabry-Perot cavity are be selectable from materials refractive indices of which fall with a large range (from n=1.26 for CaF2 to n=3.5 for Si) preferably from materials which are depositable in an amorphous state. The material combinations are selected so that only wavelengths resonant with the cavity modewill be detected. The microcavity of the RC-PIN design can also be deposited on any existing detector structure, without modification of semiconductor growth. Such a photodetector would be useful for wavelength de-multiplexing applications. Theease of layer deposition, as well as the high degree of tailorability of spectral position, spectral detection width, and maximum numerical aperture of efficient detection, make the RC-PIN attractive for use in wavelength demultiplexing applications. An exemplary RC-PIN photodetector includes a Si/SiO2 Fabry-Perot cavity electron-beam deposited on the InP substrate of a commercial InGaAs photodetector. The detection efficiency relative to a reference device was 52 percent at the resonant wavelength of 1350 nm, with a resonance width of 14 nm, and a 4 percent response for off-resonance wavelengths in the 1100-1700 nm range.