Abstract: A free-space optical communication device includes an optical fiber bundle and one or more processors. The optical fiber bundle includes a central fiber connected to a first photodetector, and a plurality of surrounding fibers, each surrounding fiber connected to a corresponding second photodetector. The one or more processors are in communication with the first photodetector and each second photodetector. The one or more processors are also configured to receive a current or voltage generated at the first photodetector and each second photodetector and to determine a pointing accuracy of a beam received at the optical fiber bundle based on the current or voltage generated at the second photodetectors.

Abstract: An optical communication system includes an optical transmitter and one or more processors. The optical transmitter is configured to output an optical signal, and includes an average-power-limited optical amplifier, such as an erbium-doped fiber amplifier (EDFA). The one or more processors are configured to receive optical signal data related to a received power for a communication link from a remote communication system and determine that the optical signal data is likely to fall below a minimum received power within a time interval. In response to the determination, the one or more processors are configured to determine a duty cycle of the optical transmitter based on a minimum on-cycle length and a predicted EDFA output power and operate the optical transmitter using the determined duty cycle to transmit an on-cycle power that is no less than the minimum required receiver power for error-free operation of the communication link.

Abstract: An optical communication system includes an optical transmitter and one or more processors. The optical transmitter is configured to output an optical signal, and includes an average-power-limited optical amplifier, such as an erbium-doped fiber amplifier (EDFA). The one or more processors are configured to receive optical signal data related to a received power for a communication link from a remote communication system and determine that the optical signal data is likely to fall below a minimum received power within a time interval. In response to the determination, the one or more processors are configured to determine a duty cycle of the optical transmitter based on a minimum on-cycle length and a predicted EDFA output power and operate the optical transmitter using the determined duty cycle to transmit an on-cycle power that is no less than the minimum required receiver power for error-free operation of the communication link.

Abstract: Aspects of the disclosure provide an optical communication system. The system may include a receiver lens system configured to receive a light beam from a remote optical communication system and direct the light beam to a photodetector. The system may also include the photodetector. The photodetector may be configured to convert the received light beam into an electrical signal, and the photodetector may be positioned at a focal plane of the receiver lens system. The system may also include a phase-aberrating element arranged with respect to the receiver lens system and the photodetector such that the phase-aberrating element is configured to provide uniform angular irradiance at the focal plane of the receiver lens system.

Abstract: An optical communication device is provided that includes a first lens having a first surface and a second surface, a second lens having a third surface and a fourth surface, an optical fiber configured to output light including a plurality of ray bundles, and a photodetector located at the fourth surface of the second lens. The first lens is configured to cause the light output from the optical fiber to form an image at an image plane located at the third surface of the second lens. The second lens is configured to cause subsets of the ray bundles received at the third surface of the second lens to intersect or overlap at the photodetector in a smaller cross-sectional area than at the third surface of the second lens.

Abstract: Aspects of the disclosure provide an optical communication system. The system may include a receiver lens system configured to receive a light beam from a remote optical communication system and direct the light beam to a photodetector. The system may also include the photodetector. The photodetector may be configured to convert the received light beam into an electrical signal, and the photodetector may be positioned at a focal plane of the receiver lens system. The system may also include a phase-aberrating element arranged with respect to the receiver lens system and the photodetector such that the phase-aberrating element is configured to provide uniform angular irradiance at the focal plane of the receiver lens system.

Abstract: Aspects of the disclosure provide an optical communication system. The system may include a receiver lens system configured to receive a light beam from a remote optical communication system and direct the light beam to a photodetector. The system may also include the photodetector. The photodetector may be configured to convert the received light beam into an electrical signal, and the photodetector may be positioned at a focal plane of the receiver lens system. The system may also include a phase-aberrating element arranged with respect to the receiver lens system and the photodetector such that the phase-aberrating element is configured to provide uniform angular irradiance at the focal plane of the receiver lens system.

Abstract: An optical communication system includes an optical transmitter and one or more processors. The optical transmitter is configured to output an optical signal, and includes an average-power-limited optical amplifier, such as an erbium-doped fiber amplifier (EDFA). The one or more processors are configured to receive optical signal data related to a received power for a communication link from a remote communication system and determine that the optical signal data is likely to fall below a minimum received power within a time interval. In response to the determination, the one or more processors are configured to determine a duty cycle of the optical transmitter based on a minimum on-cycle length and a predicted EDFA output power and operate the optical transmitter using the determined duty cycle to transmit an on-cycle power that is no less than the minimum required receiver power for error-free operation of the communication link.

Abstract: An optical communication system includes an optical transmitter and one or more processors. The optical transmitter is configured to output an optical signal, and includes an average-power-limited optical amplifier, such as an erbium-doped fiber amplifier (EDFA). The one or more processors are configured to receive optical signal data related to a received power for a communication link from a remote communication system and determine that the optical signal data is likely to fall below a minimum received power within a time interval. In response to the determination, the one or more processors are configured to determine a duty cycle of the optical transmitter based on a minimum on-cycle length and a predicted EDFA output power and operate the optical transmitter using the determined duty cycle to transmit an on-cycle power that is no less than the minimum required receiver power for error-free operation of the communication link.

Abstract: An optical communication device is provided that includes a first lens having a first surface and a second surface, a second lens having a third surface and a fourth surface, an optical fiber configured to output light including a plurality of ray bundles, and a photodetector located at the fourth surface of the second lens. The first lens is configured to cause the light output from the optical fiber to form an image at an image plane located at the third surface of the second lens. The second lens is configured to cause subsets of the ray bundles received at the third surface of the second lens to intersect or overlap at the photodetector in a smaller cross-sectional area than at the third surface of the second lens.

Abstract: An optical communication system includes an optical transmitter and one or more processors. The optical transmitter is configured to output an optical signal, and includes an average-power-limited optical amplifier, such as an erbium-doped fiber amplifier (EDFA). The one or more processors are configured to receive optical signal data related to a received power for a communication link from a remote communication system and determine that the optical signal data is likely to fall below a minimum received power within a time interval. In response to the determination, the one or more processors are configured to determine a duty cycle of the optical transmitter based on a minimum on-cycle length and a predicted EDFA output power and operate the optical transmitter using the determined duty cycle to transmit an on-cycle power that is no less than the minimum required receiver power for error-free operation of the communication link.

Abstract: The disclosure provides a communication system that includes sensors, a plurality of components, and processors. The sensors receive measurements related to a state of the communication system. The processors receive an indication of an amount of received power at a remote communication system and estimate a state of the plurality of components based on the received one or more measurements and the received indication. Using the indication and the estimated state, the processors determine whether the amount of received power is likely to fall below a minimum received power within a given time interval. When it is likely, the processors select an adjustment technique of a plurality of adjustment techniques for adjusting a data rate of the outbound signal and adjust a given component of the communication system using the selected adjustment technique to change the data rate of the outbound signal.

Abstract: The disclosure provides for a free-space optical communication system that includes a first lens group, a field corrector lens, and a second lens group. The first lens group is configured to receive light received from a remote free-space optical transmitter. The first lens group has a first focal plane. The field corrector lens is positioned between the first lens group and the first focal plane of the first lens group and positioned closer to the first focal plane than the first lens group. The first lens group also is made of material having an index of refraction of at least 2.0, and has a second focal plane. The second lens group is positioned at the second focal plane of the field corrector lens and is configured to couple light to a sensor.

Abstract: Aspects of the disclosure provide techniques for automatic repeat request (ARQ) in a free-space optical communication (FSOC) architecture. These techniques, including block-selective ARQ, adaptive retransmission delay, and random seed scrambling, can be used individually or in combination to combat problems involving frame loss or corruption. These techniques enable the system to rapidly recover by streamlining the retransmission process. For instance, block-selective ARQ acknowledges variable length blocks of frames in the return stream from the receiver to the transmitter. Adaptive retransmission delay allows the retransmission delay to grow in the absence of feedback by the receiver, up to some defined limit. And with random seed sampling, a scrambling sequence is incorporated to aid with frame syncing, which avoids the need for a line code. These aspects of the technology provide a robust communication process, and also reduce overhead costs associated with unnecessary retransmissions.

Abstract: Aspects of the disclosure provide techniques for automatic repeat request (ARQ) in a free-space optical communication (FSOC) architecture. These techniques, including block-selective ARQ, adaptive retransmission delay, and random seed scrambling, can be used individually or in combination to combat problems involving frame loss or corruption. These techniques enable the system to rapidly recover by streamlining the retransmission process. For instance, block-selective ARQ acknowledges variable length blocks of frames in the return stream from the receiver to the transmitter. Adaptive retransmission delay allows the retransmission delay to grow in the absence of feedback by the receiver, up to some defined limit. And with random seed sampling, a scrambling sequence is incorporated to aid with frame syncing, which avoids the need for a line code. These aspects of the technology provide a robust communication process, and also reduce overhead costs associated with unnecessary retransmissions.

Abstract: The disclosure provides a communication system that includes sensors, a plurality of components, and processors. The sensors receive measurements related to a state of the communication system. The processors receive an indication of an amount of received power at a remote communication system and estimate a state of the plurality of components based on the received one or more measurements and the received indication. Using the indication and the estimated state, the processors determine whether the amount of received power is likely to fall below a minimum received power within a given time interval. When it is likely, the processors select an adjustment technique of a plurality of adjustment techniques for adjusting a data rate of the outbound signal and adjust a given component of the communication system using the selected adjustment technique to change the data rate of the outbound signal.

Abstract: The disclosure provides for an optical communication device that includes a photodetector, an optical fiber, a first lens, and a second lens. The optical fiber may be configured to relay light. The first lens may include a first surface and a second surface and has an image plane. The first lens may be configured to receive the light output from the optical fiber, where the received light has a first cross-sectional area at the first surface. The second lens may include a third surface positioned at the image plane of the first lens and a fourth surface positioned adjacent to the photodetector. The second lens may be configured to receive the light output from the first lens and to output light having a second cross-sectional area at the fourth surface that is smaller than the first cross-sectional area.

Abstract: Aspects of the disclosure provide techniques for automatic repeat request (ARQ) in a free-space optical communication (FSOC) architecture. These techniques, including block-selective ARQ, adaptive retransmission delay, and random seed scrambling, can be used individually or in combination to combat problems involving frame loss or corruption. These techniques enable the system to rapidly recover by streamlining the retransmission process. For instance, block-selective ARQ acknowledges variable length blocks of frames in the return stream from the receiver to the transmitter. Adaptive retransmission delay allows the retransmission delay to grow in the absence of feedback by the receiver, up to some defined limit. And with random seed sampling, a scrambling sequence is incorporated to aid with frame syncing, which avoids the need for a line code. These aspects of the technology provide a robust communication process, and also reduce overhead costs associated with unnecessary retransmissions.

Abstract: Aspects of the disclosure provide techniques for automatic repeat request (ARQ) in a free-space optical communication (FSOC) architecture. These techniques, including block-selective ARQ, adaptive retransmission delay, and random seed scrambling, can be used individually or in combination to combat problems involving frame loss or corruption. These techniques enable the system to rapidly recover by streamlining the retransmission process. For instance, block-selective ARQ acknowledges variable length blocks of frames in the return stream from the receiver to the transmitter. Adaptive retransmission delay allows the retransmission delay to grow in the absence of feedback by the receiver, up to some defined limit. And with random seed sampling, a scrambling sequence is incorporated to aid with frame syncing, which avoids the need for a line code. These aspects of the technology provide a robust communication process, and also reduce overhead costs associated with unnecessary retransmissions.

Abstract: A data rate at which data can be transmitted is adapted in real-time to power fluctuations. Bits of data to be sent by a transmitter are mapped to physical symbols, where a first modulation uses a first number of bits per pulse and a second modulation uses a second number of bits per pulse. Both modulations are sent, with one nested inside the other. A receiver decodes one or both bit streams, depending on a signal to noise ratio (SNR). In this regard, the data rate traces the received power, and higher data rates may be used despite periods of power fluctuations. This technique enables rapid, or even instantaneous, changes by using nested modulation. Moreover, a fast feedback mechanism is used to inform the transmitter when to change its modulation and to retransmit bits lost during an initial transmission.