摘要： We demonstrate a high signal-to-noise ratio (SNR) for a photonic-crystal nanophotodetector (PD). The ultralow-capacitance nano-PD can be terminated with a load resistor with a resistance as high as 59 kX for ef?cient light-to-voltage conversion, and its strong thermal-noise suppression leads to an SNR that is 30 dB higher than that of the conventional p-i-n PD terminated with a 50-X load. The noise equivalent power is only 500 fW/(cid:2)Hz, while a gigahertz-level bandwidth can be maintained when considering that the PD capacitance is only 1 fF. Theoretically, this allows optical reception at less than 100 aJ to obtain a bit error rate of 10–9. The resistor-loaded nano-PD requires a small electrical biasing energy comparable to the optical energy, which is remarkably energy saving compared with avalanche PDs or other PDs integrated with ampli?ers. Such a receiver promises a dense optical interface with CMOS electronics in photonic networking and processing chips.