A Monothically Integrated Dual-Wavelength Tunable Photodetector Based on a Taper GaAs Substrate

The design and fabrication of a monothically integrated dual-wavelength tunable photodetector are reported. The dual-wavelength character is realized by fabricating a taper substrate. The photodetector, operating at a long wavelength, is monothically integrated by using a heteroepitaxy growth of $ \hbox{InP-In}_{0.53}\hbox{Ga}_{0.47}\hbox{As-InP}$ p-i-n structure on a GaAs-based GaAs/AlAs Fabry–PÉrot-filter structure, which can be tuned via the thermal-optic effect. High-quality heteroepitaxy was realized by employing a thin low-temperature buffer layer. The integrated device with a dual-peak distance of 7 nm (1530, 1537 nm), a wavelength-tuning range of 5.0 nm, and a 3-dB bandwidth of 5.9 GHz was demonstrated, agreeing with the theoretical simulation.