Regrowth-free waveguide-integrated photodetector with efficient total-internal-reflection coupling

A novel technique utilizing an etched total-internal-reflection mirror for vertical waveguide-to-photodetector coupling is described. An 83% quantum efficiency and 5-GHz bandwidth are achieved at lambda =0.84 mu in a GaAs MSM photodetector illuminated by a low-loss (0.5 dB/cm) AlGaAs double-heterostructure (DH) waveguide. A significant advantage of total-internal-reflection coupling is its compatibility with the integration of low-loss active DH waveguide components without requiring epitaxial regrowth. This coupling technique is independent of both optical wavelength and polarization, and permits efficient waveguide coupling to extremely small-area photodetectors.<
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