Characterization of single-photon detectors using a continuous wave laser source
AssigneeAT&T Intelletual Property I, L.P.
InventorsMichael Brodsky, Cristian Antonelli, Jungmi Oh
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Abstract
Operational parameters of a single-photon detector are determined with a continuous wave laser source. At a fixed trigger, a dark count probability and a series of count probabilities at different optical powers are determined. A particular optical power is selected by using a wide-range variable attenuator to attenuate the optical power of the continuous wave laser. The dark count probability and the count probabilities are determined for different trigger rates. The operational parameters include efficiency, afterpulsing constant, and detrap time. The operational parameters are computed by fitting the computed dark count probabilities and count probabilities to a user-defined relationship.
Claims17
A method for characterizing a single-photon detector operating with a plurality of trigger rates, the method comprising:
- for each of the plurality of trigger rates:
- recording, by a processor, dark counts with the single-photon detector and computing a dark count probability;
- and
- for each of a plurality of optical powers generated by a continuous wave laser,
- recording, by the processor, counts with the single-photon detector and computing a count probability;
- calculating, by the processor, a single-photon detector operational parameter based on the dark count probability and the count probability, wherein the count probability is derived from evaluating a probability of an afterpulse at a predetermined time interval;
- and
- fitting, by the processor, the dark count probability and the count probability for a user-defined relationship, wherein the user-defined relationship comprises a probability of detecting photons generated by a specific source in an absence of dark counts and afterpulses, an average number of photons per detector gate and a trigger rate, wherein the probability of detecting photons generated by the specific source in the absence of dark counts is exponentially related to the average number of photons per detector gate.
An apparatus comprising:
- a processor;
- and
- a memory to store computer program instructions, the computer program instructions when executed on the processor cause the processor to perform operations comprising:
- for each of the plurality of trigger rates:
- recording dark counts with the single-photon detector and computing a dark count probability;
- and
- for each of a plurality of optical powers generated by a continuous wave laser,
- recording counts with the single-photon detector and computing a count probability;
- calculating a single-photon detector operational parameter based on the dark count probability and the count probability, wherein the count probability is derived from evaluating a probability of an afterpulse at a predetermined time interval;
- and
- fitting the dark count probability and the count probability for a user-defined relationship, wherein the user-defined relationship comprises a probability of detecting photons generated by a specific source in an absence of dark counts and afterpulses, an average number of photons per detector gate and a trigger rate, wherein the probability of detecting photons generated by the specific source in the absence of dark counts is exponentially related to the average number of photons per detector gate.
A tangible computer readable medium storing computer program instructions for characterizing a single-photon detector operating with a plurality of trigger rates, which, when executed on a processor, cause the processor to perform operations comprising:
- for each of the plurality of trigger rates:
- recording dark counts with the single-photon detector and computing a dark count probability;
- and
- for each of a plurality of optical powers generated by a continuous wave laser,
- recording counts with the single-photon detector and computing a count probability;
- calculating a single-photon detector operational parameter based on the dark count probability and the count probability, wherein the count probability is derived from evaluating a probability of an afterpulse at a predetermined time interval;
- and
- fitting dark count probability and the count probability for a user-defined relationship, wherein the user-defined relationship comprises a probability of detecting photons generated by a specific source in an absence of dark counts and afterpulses, an average number of photons per detector gate and a trigger rate, wherein the probability of detecting photons generated by the specific source in the absence of dark counts is exponentially related to the average number of photons per detector gate.
A method for determining an effective gate window τg of a single-photon detector operating with a trigger rate, the method comprising:
- for each of a plurality of optical powers Pcw generated by a continuous wave laser, recording, by a processor, counts with the single-photon detector and computing, by the processor, a corresponding count probability Pc(Pcw);
- for each of a plurality of average optical powers Pp generated by a pulse laser, recording, by the processor, counts with the single-photon detector and computing, by the processor, a corresponding count probability Pc(Pp);
- determining, by the processor, a particular optical power Pcwo and a particular average optical power Ppo for which the corresponding count probabilities are equal:
- Pc(Pcwo)=Pc(Ppo);
- and
- calculating the effective gate window τg from a relationship
- τg=10(Ppo−Pcwo−10 log10(R))/10,
- wherein R is the trigger rate.
Dependencies are inferred from the claim text.