42 GHz p.i.n germanium photodetector integrated in a silicon-on-insulator waveguide

Overview & Synopsis

A compact pin Ge photodetector is integrated in submicron SOI rib waveguide. The detector length is reduced down to 15 μ m using butt coupling configuration which is sufficient to totally absorb light at the wavelength of 1.55 μ m. A -3 dB bandwidth of 42 GHz has been measured at a 4V reverse bias with a responsivity as high as 1 A/W at the wavelength of 1.55 μ m and a low dark current density of 60 mA/cm2. At a wavelength of 1.52 μ m, a responsivity of 1 A/W is obtained under -0.5 V bias. The process is fully compatible with CMOS technology.