Abstract: An exemplary system includes an array of photodetectors and a control system. Each photodetector of the array of photodetectors may include a single-photon avalanche diode (SPAD) and a fast-gating circuit configured to arm and disarm the SPAD. The control system is configured to control a current drawn by the array of photodetectors.

Abstract: A wearable system includes a stacked photodetector assembly including a first wafer including a single photon avalanche diode (SPAD), the first wafer having a thickness T1 configured to minimize absorption by the first wafer of photons included in light incident upon the first wafer while the SPAD is in a disarmed state, and a second wafer having a thickness T2 including a fast gating circuit electrically coupled to the SPAD and configured to arm and disarm the SPAD, the second wafer bonded to the first wafer in a stacked configuration. The fast gating circuit includes a capacitor configured to be charged, while the SPAD is in the disarmed state, with a bias voltage by a voltage source, and supply, while the SPAD is in an armed state, the bias voltage to the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.

Abstract: An exemplary photodetector system includes a plurality of photodetectors connected in parallel and a processor communicatively coupled to the plurality of photodetectors. The processor is configured to receive an accumulated output from the plurality of photodetectors. The accumulated output represents an accumulation of respective outputs from each of the plurality of photodetectors detecting photons during a predetermined measurement time period that occurs in response to a light pulse being directed toward a target within a body. The processor is further configured to determine, based on the accumulated output, a temporal distribution of photons detected by the plurality of photodetectors, and generate, based on the temporal distribution of photons, a histogram representing a light pulse response of the target within the body.

Abstract: An exemplary wearable brain interface system includes a headgear configured to be worn on a head of a user, a plurality of photodetector units configured to attach to the headgear, and a master control unit coupled to each of the photodetector units and configured to control the photodetector units by directing a photodetector of each photodetector unit to detect photons of light.

Abstract: A wearable system for use by a user includes a photodetector configured to detect a photon of a light pulse after the photon reflects from a target internal to the user. The photodetector includes a single photon avalanche diode (SPAD) and a capacitor configured to be charged, while the SPAD is in a disarmed state, with a bias voltage by a voltage source, and supply, when the SPAD is put in an armed state, the bias voltage to an output node of the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.

Abstract: An exemplary non-invasive wearable brain interface system includes a headgear configured to be worn on a head of a user, a plurality of self-contained photodetector units configured to removably attach to the headgear, the photodetector units each comprising a plurality of photodetectors configured to detect photons of light after the photons reflect from a target within a brain of the use, and a master control unit coupled to each of the photodetector units and configured to control the photodetector units.

Abstract: An exemplary stacked photodetector assembly includes a first wafer and a second wafer bonded to the first wafer. The first wafer includes a SPAD and has a thickness T1 configured to minimize absorption by the first wafer of photons included in light incident upon the first wafer while the SPAD is in a disarmed state. The second wafer has a thickness T2 configured to provide structural support for the first wafer. The stacked photodetector assembly includes a fast gating circuit electrically coupled to the SPAD and configured to arm and disarm the SPAD.

Abstract: A wearable system includes a stacked photodetector assembly including a first wafer including a single photon avalanche diode (SPAD), the first wafer having a thickness T1 configured to minimize absorption by the first wafer of photons included in light incident upon the first wafer while the SPAD is in a disarmed state, and a second wafer having a thickness T2 including a fast gating circuit electrically coupled to the SPAD and configured to arm and disarm the SPAD, the second wafer bonded to the first wafer in a stacked configuration. The fast gating circuit includes a capacitor configured to be charged, while the SPAD is in the disarmed state, with a bias voltage by a voltage source, and supply, while the SPAD is in an armed state, the bias voltage to the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.

Abstract: A wearable system for use by a user includes a photodetector configured to detect a photon of a light pulse after the photon reflects from a target internal to the user. The photodetector includes a single photon avalanche diode (SPAD) and a capacitor configured to be charged, while the SPAD is in a disarmed state, with a bias voltage by a voltage source, and supply, when the SPAD is put in an armed state, the bias voltage to an output node of the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.

Abstract: An exemplary non-invasive wearable brain interface system includes a headgear configured to be worn on a head of a user, a plurality of self-contained photodetector units configured to removably attach to the headgear, the photodetector units each comprising a plurality of photodetectors configured to detect photons of light after the photons reflect from a target within a brain of the use, and a master control unit coupled to each of the photodetector units and configured to control the photodetector units.

Abstract: An exemplary stacked photodetector assembly includes a first wafer and a second wafer bonded to the first wafer. The first wafer includes a SPAD and has a thickness T1 configured to minimize absorption by the first wafer of photons included in light incident upon the first wafer while the SPAD is in a disarmed state. The second wafer has a thickness T2 configured to provide structural support for the first wafer. The stacked photodetector assembly includes a fast gating circuit electrically coupled to the SPAD and configured to arm and disarm the SPAD.

Abstract: An exemplary photodetector includes a SPAD and a capacitor. The capacitor is configured to be charged, while the SPAD is in a disarmed state, with a bias voltage by a voltage source. The capacitor is further configured to supply, when the SPAD is put in an armed state, the bias voltage to an output node of the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.

Abstract: An exemplary non-invasive wearable brain interface system includes a headgear configured to be worn on a head of the user and a plurality of self-contained photodetector units configured to removably attach to the headgear. The photodetector units each include a plurality of photodetectors configured to detect photons of light after the photons reflect from a target within a brain of the user. The brain interface system further includes a master control unit communicatively coupled to each of the photodetector units by way of a plurality of wires and configured to control the photodetector units, the master control unit comprising an input power port configured to connect to a power cable that provides power from a power source for the master control unit and the photodetector units.

Abstract: An exemplary photodetector includes a SPAD and a capacitor. The capacitor is configured to be charged, while the SPAD is in a disarmed state, with a bias voltage by a voltage source. The capacitor is further configured to supply, when the SPAD is put in an armed state, the bias voltage to an output node of the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.