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Patent US10312387
Issued 2019-06-04
Single Photon Detection Using A Resonator With An Absorber
A single photon detector (SPD) includes a resonator to store probe photons at a probe wavelength and an absorber disposed in the resonator to absorb a signal photon at a signal wavelength. The absorber is also substantially transparent to the probe photons. In the absence of the signal photon, the resonator is on resonance with the probe photons, thereby confining the probe photons within the resonator. Absorption of the signal photon by the absorber disturbs the resonant condition of the resonator, causing the resonator to release multiple probe photons. A photodetector (PD) then detects these multiple probe photons to determine the presence of the signal photon.
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- 1. An apparatus for detecting a signal photon at a first wavelength, the apparatus comprising:
a resonator to store a plurality of probe photons at a second wavelength different from the first wavelength; an absorber, disposed at least partially in the resonator and substantially transparent to the plurality of probe photons, to absorb the signal photon, absorption of the signal photon causing a change of a resonant wavelength of the resonator, the change of the resonant wavelength causing release of at least some of the plurality of probe photons from the resonator; and a detector, in optical communication with the resonator, to generate an electrical signal in response to detection of the at least some of the plurality of probe photons, the electrical signal indicating a presence of the signal photon.
- 14. A method of detecting a signal photon at a first wavelength, the method comprising:
coupling a plurality of probe photons at a second wavelength, different from the first wavelength, into a resonator, the resonator including an absorber disposed at least partially in the resonator and substantially transparent to the plurality of probe photons; absorbing the signal photon with the absorber, the absorber changing a resonant wavelength of the resonator in response to absorption of the signal photon, thereby releasing at least some of the plurality of probe photons from the resonator; and detecting the at least some of the plurality of probe photons; and determining a presence of the signal photon based on detection of the at least some of the plurality of probe photons.
- 21. A single-photon detector to detect a signal photon at a signal wavelength, the single-photon detector comprising:
an input waveguide to receive a plurality of probe photons at a probe wavelength less than half of the signal wavelength; a micro-ring resonator, evanescently coupled to the input waveguide, to receive the plurality of probe photons, the input waveguide comprising:
a first section, evanescently coupled to a first location of the micro-ring resonator, to couple out a first portion of the plurality of probe photons; and
a second section, evanescently coupled to a second location of the micro-ring resonator, to couple out a second portion of the probe photons, the second portion destructively interfering with the first portion;
an absorber, disposed at least partially in the micro-ring resonator and substantially transparent at the probe wavelength, to absorb the signal photon, absorption of the signal photon causing a change of a resonant wavelength of the micro-ring resonator releasing at least some of the plurality of probe photons from the micro-ring resonator, the absorber comprising a III-N semiconductor having a bandgap energy at least two times greater than a photon energy of the probe photons in the plurality of probe photons; and a detector, in optical communication with the resonator, to detect the at least some of the plurality of probe photons.
