<title>Very narrow linewidth tunable distributed Bragg reflector photodetector</title>

Abstract

We demonstrate a photodetector with a very narrow spectral linewidth (less than 2 angstroms) and a 35 angstroms tuning range is demonstrated. The absorption medium is made up of 3 pairs of InGaAs/GaAs Quantum Wells and the operating wavelength of the photodetector is approximately 960 nm. The photodetector features a horizontal resonant cavity in which feedback is achieved using Distributed Feedback Reflectors (DFB). The DFB gratings have a periodicity of 2850 angstroms and provide feedback through the second order of diffraction. The grating periodicity was chosen to facilitate the coupling of normally incident light into the 0.25 micrometers -thick GaAs waveguide of the cavity through the first order of diffraction. The optical and electrical paths in this photodetector are completely orthogonal. Consequently, this normal incidence horizontal resonant cavity photodetector is completely integrable into Wavelength Division Demultiplexing and other Optoelectronic Integrated Circuits with a potential for high speed operation.