High quantum efficiency, 40 GHz InGaAs twin waveguide PIN photodetectors

Asymmetric twin-waveguide (ATG) technology wherein active and passive devices are formed in two separate waveguides, and light is coupled between them via a lateral taper, has proven to be a versatile integration platform for photonic integrated circuits. Here, we demonstrate a /spl lambda/=1.55 /spl mu/m wavelength, high-speed, high-efficiency photodetector made by integrating a spot-size converter with an evanescently coupled In/sub 0.53/Ga/sub 0.47/As absorption region. While several versions of waveguide photodetectors have been proposed to overcome the bandwidth-efficiency trade-off, the ATG design provides a simple means of fabrication with the possibility of monolithically integrating detectors with other optical components such as semiconductor optical amplifiers and in-plane waveguide filters.