A Monolithically Integrated Long-Wavelength Balanced Photodiode Using Asymmetric Twin-Waveguide Technology

We demonstrate a long-wavelength monolithically integrated photodiode pair balanced to within 0.4 dB. The (15/spl plusmn/1) GHz bandwidth balanced photodiode pair has minimum dark current of 5 nA, a responsivity of (0.32/spl plusmn/0.02) A/W at 1.55-μm wavelength, linearity up to +3-dBm input optical power, and a common mode rejection ratio of (34/spl plusmn/2) dB. The asymmetric twin-waveguide architecture used makes it possible for integration of the detector pair with other optical components such as semiconductor optical amplifiers, lasers, modulators, and in-plane waveguide-filters.