Extended Data Fig. 2: Polysilicon avalanche photodetector.
From: Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip
a, Current–voltage curve of the microring photodiode under dark and illumination for an input optical power of 20 µW. Dynamic range is about 60 dB and about 10 dB at 0 V and 16 V, respectively. b, One microring photodetector resonance (top) and the corresponding photo-current (bottom) as the wavelength is swept across the resonance. The loaded Q-factor (Qloaded) of the microring is about 10,000. The fit is obtained through least-squares optimization of a model that includes a Lorentzian resonance for the microring and accounts for the reflections from the end facets of the chip to model the Fabry–Perot resonances observed in the transmission curve. c, Noise equivalent power (NEP, blue curve) of the photodiode estimated from the dark-current shot noise, which dominates the detector noise. Avalanche gain is 13 at 16 V bias, with an noise equivalent power of 0.27 pW Hz−1/2. The simulated signal-to-noise ratio (SNR) (red curve) at the output of the optical receiver, assuming an optical signal of 1 µW, and a receiver circuit input-referred noise spectral density of 1 pA Hz−1/2. d, The responsivity of the photodetector versus input optical power, showing minimal power dependency. The error bar is estimated based on a ±5% error in estimating the optical power in the waveguide before coupling into the detector. This error comes from variations in fibre to chip coupling efficiency owing to fibre-grating coupler misalignment. e, f, Eye diagrams at 12.5 Gb s−1 at 0 V and 14.5 V reverse bias.
