Monolithically integrated tunable dual-wavelength photodetector with flat-top response

This paper elaborates the design and analysis of a novel monolithically integrated tunable dual-wavelength photodetector which can be formed by heteroepitaxial growth of an InP-based p-i-n absorption structure on a GaAs-based Fabry–Pérot filter. The photodetector presents two response peaks resulting from the introduction of 4-step Fabry–Pérot cavity. The wavelength spacing between the two peaks, as well as the peak shapes, can be accurately and easily tailored by adjusting the corresponding step height. This photodetector can be tuned via thermal-optic effect. With optimum design by using Transfer Matrix Method, the detectable wavelength range of the photodetector will be twice as that of its counterpart being with a uniform filter cavity; what is more, flat-top responses of the two peaks can also be obtained, simultaneously. We discuss the epitaxial growth and fabrication of the photodetector at the end, indicating the mature technique available for the device.