InP-based Single Photon Detectors with Active Negative Feedback

From the perspective of performance, reliability, and cost, the most practical photodetector available today with single photon sensitivity between 1.0 and 1.6 ìm is the InGaAs/InP single photon avalanche diode (SPAD). However, even the best InP-based SPADs have photon counting rate limitations of ~1 – 10 MHz. For applications ranging from quantum information science to covert short-wave infrared imaging, single photon detectors with much faster counting rates in the range of 100 MHz – 1 GHz will be essential. A primary shortcoming of conventional SPADs is the positive feedback inherent in their avalanche dynamics and performance degradation associated with it. We propose to radically improve upon these structures by monolithically integrating negative feedback elements to create negative feedback avalanche diodes (NFADs) with self-limiting avalanches exhibiting highly deterministic gain values. Self-limited avalanches will greatly reduce latency problems caused by afterpulsing, offering the potential for repetition rates exceeding 100 MHz, and highly deterministic gains will provide much lower excess noise. NFAD device operation will also be greatly simplified relative to SPADs since NFADs can be operated with just a single dc bias. We will investigate several approaches towards incorporating negative feedback using active elements and compare these approaches with on-going work that entails the use of passive negative feedback. Long-term prospects include the increase of repetition rates beyond 1 GHz and the achieving of photon number resolution using multiplexed NFAD formats.