APD direct detection receiver OEIC operating 14.1 dB above the shot noise quantum limit

This paper presents a highly-sensitive direct detection receiver optoelectronic integrated circuit (OEIC) with a dot-cathode avalanche photodiode (APD) in 180 nm high-voltage CMOS. Experimental sensitivity results of the APD receiver are compared to a reference PIN photodiode receiver. Both photodiodes are integrated on the same wafer, with identical integrate-and-dump source-follower front-end. At a wavelength of 642 nm, bit rate of 100 Mb∕s with 80 % return-to-zero (RZ) on-off keying (OOK) modulation, and reference BER = 0.002, the APD receiver achieves a sensitivity of -56.6 dBm. The sensitivity equals a gap of 14.1 dB to the shot noise quantum limit, that is an average of 71 photons per bit. The minimum normalized sensitivity (ηP-) improvement over the PIN receiver is 4 dB.