Abstract: Communication bottlenecks, particularly in the downlink direction, are a common problem for many CubeSat developers. As described herein, a CubeSat module for a CubeSat comprises an optical transmitter to transmit data to a remote terminal, a receiver to acquire an optical beacon from a remote terminal, and a fine-pointing module operably and directly coupleable to a coarse-pointing module of the CubeSat. The fine-pointing module is configured to point the optical transmitter toward the remote terminal with an accuracy range that overlaps with an accuracy range of the coarse-pointing module of the CubeSat so as to establish a communications link between the CubeSat and the remote terminal over a low-Earth-orbit (LEO) distance.

Abstract: Communication bottlenecks, particularly in the downlink direction, are a common problem for many CubeSat developers. As described herein, a CubeSat module for a CubeSat comprises an optical transmitter to transmit data to a remote terminal, a receiver to acquire an optical beacon from a remote terminal, and a fine-pointing module operably and directly coupleable to a coarse-pointing module of the CubeSat. The fine-pointing module is configured to point the optical transmitter toward the remote terminal with an accuracy range that overlaps with an accuracy range of the coarse-pointing module of the CubeSat so as to establish a communications link between the CubeSat and the remote terminal over a low-Earth-orbit (LEO) distance.

Abstract: Communication bottlenecks, particularly in the downlink direction, are a common problem for many CubeSat developers. As described herein, a CubeSat module for a CubeSat comprises an optical transmitter to transmit data to a remote terminal, a receiver to acquire an optical beacon from a remote terminal, and a fine-pointing module operably and directly coupleable to a coarse-pointing module of the CubeSat. The fine-pointing module is configured to point the optical transmitter toward the remote terminal with an accuracy range that overlaps with an accuracy range of the coarse-pointing module of the CubeSat so as to establish a communications link between the CubeSat and the remote terminal over a low-Earth-orbit (LEO) distance.

Abstract: An apparatus for generating a processed optical signal includes a first laser configured to emit a first optical signal in response to a first drive signal. The first optical signal has a first phase shift depending on a first integrated amplitude of the first drive signal. The apparatus also includes a spectral-temporal filter, in optical communication with the first laser, to change a first spectral profile and a first temporal profile of the first optical pulse so as to generate the processed optical signal. Replacing a conventional continuous-wave (CW) laser and external modulation with filter-based modulation can achieve the same or better performance without high-fidelity low-noise input signals.

Abstract: An apparatus for generating a processed optical signal includes a first laser configured to emit a first optical signal in response to a first drive signal. The first optical signal has a first phase shift depending on a first integrated amplitude of the first drive signal. The apparatus also includes a spectral-temporal filter, in optical communication with the first laser, to change a first spectral profile and a first temporal profile of the first optical pulse so as to generate the processed optical signal. Replacing a conventional continuous-wave (CW) laser and external modulation with filter-based modulation can achieve the same or better performance without high-fidelity low-noise input signals.

Abstract: An optical receiver includes a cascade of optical filtering elements, each of which selects spectral components from incoming optical signals at a wavelengths aligned to filter passbands. The selected spectral components may be optically combined to form k pairs of intermediary signals, where k=log2(M). By comparing the k pairs of intermediary signals, k bits of a digital signal representing the incident signal may be generated. The filtering elements may be configured to perform demultiplexing and demodulation simultaneously, increasing functionality and reducing excess losses.

Abstract: The present invention provides a simple means of demodulating optical signals, e.g. wideband M-ary orthogonal. The demodulator comprises an optical processor and a comparison module. The optical processor transforms M input optical signals into 2 log2(M) intermediary optical signals and the comparison module determines the logical representation of the input data based on log2(M) binary comparisons of the optical power of the intermediary signals. Example embodiments may be reconfigurable to receive optical signals using M-FSK, M-PPM, M-PolSK, and hybrid M-ary orthogonal modulation formats. Example embodiments also offer small size, weight and power consumption for both free-space and fiber optic environments as well as improved receiver sensitivity and reduced electron bandwidth requirements.

Abstract: Communication bottlenecks, particularly in the downlink direction, are a common problem for many CubeSat developers. As described herein, a CubeSat module for a CubeSat comprises an optical transmitter to transmit data to a remote terminal, a receiver to acquire an optical beacon from a remote terminal, and a fine-pointing module operably and directly coupleable to a coarse-pointing module of the CubeSat. The fine-pointing module is configured to point the optical transmitter toward the remote terminal with an accuracy range that overlaps with an accuracy range of the coarse-pointing module of the CubeSat so as to establish a communications link between the CubeSat and the remote terminal over a low-Earth-orbit (LEO) distance.

Abstract: Communication bottlenecks, particularly in the downlink direction, are a common problem for many CubeSat developers. As described herein, a CubeSat module for a CubeSat comprises an optical transmitter to transmit data to a remote terminal, a receiver to acquire an optical beacon from a remote terminal, and a fine-pointing module operably and directly coupleable to a coarse-pointing module of the CubeSat. The fine-pointing module is configured to point the optical transmitter toward the remote terminal with an accuracy range that overlaps with an accuracy range of the coarse-pointing module of the CubeSat so as to establish a communications link between the CubeSat and the remote terminal over a low-Earth-orbit (LEO) distance.

Abstract: An optical receiver includes a cascade of optical filtering elements, each of which selects spectral components from incoming optical signals at a wavelengths aligned to filter passbands. The selected spectral components may be optically combined to form k pairs of intermediary signals, where k=log2(M). By comparing the k pairs of intermediary signals, k bits of a digital signal representing the incident signal may be generated. The filtering elements may be configured to perform demultiplexing and demodulation simultaneously, increasing functionality and reducing excess losses.

Abstract: A burst-mode phase shift keying (PSK) communications apparatus according to an embodiment of the present invention enables practical, power-efficient, multi-rate communications between an optical transmitter and receiver. Embodiments may operate on differential PSK (DPSK) signals. An embodiment of the apparatus includes an average power limited optical transmitter that transmits at a selectable data rate with data transmitted in bursts, the data rate being a function of a burst-on duty cycle. DPSK symbols are transmitted in bursts, and the data rate may be varied by changing the ratio of the burst-on time to the burst-off time. This approach offers a number of advantages over conventional DPSK implementations, including near-optimum photon efficiency over a wide range of data rates, simplified multi-rate transceiver implementation, and relaxed transmit laser line-width requirements at low data rates.

Abstract: A burst-mode phase shift keying (PSK) communications apparatus according to an embodiment of the present invention enables practical, power-efficient, multi-rate communications between an optical transmitter and receiver. Embodiments may operate on differential PSK (DPSK) signals. An embodiment of the apparatus includes an average power limited optical transmitter that transmits at a selectable data rate with data transmitted in bursts, the data rate being a function of a burst-on duty cycle. DPSK symbols are transmitted in bursts, and the data rate may be varied by changing the ratio of the burst-on time to the burst-off time. This approach offers a number of advantages over conventional DPSK implementations, including near-optimum photon efficiency over a wide range of data rates, simplified multi-rate transceiver implementation, and relaxed transmit laser line-width requirements at low data rates.

Abstract: A burst-mode phase shift keying (PSK) communications system according to an embodiment of the present invention enables practical, power-efficient, multi-rate communications between an optical transmitter and receiver. Embodiments may operate on differential PSK (DPSK) signals. An embodiment of the system utilizes a single interferometer in the receiver with a relative path delay that is matched to the DPSK symbol rate of the link. DPSK symbols are transmitted in bursts, and the data rate may be varied by changing the ratio of the burst-on time to the burst-off time. This approach offers a number of advantages over conventional DPSK implementations, including near-optimum photon efficiency over a wide range of data rates, simplified multi-rate transceiver implementation, and relaxed transmit laser line-width requirements at low data rates.

Abstract: Communication bottlenecks, particularly in the downlink direction, are a common problem for many CubeSat developers. As described herein, a CubeSat module for a CubeSat comprises an optical transmitter to transmit data to a remote terminal, a receiver to acquire an optical beacon from a remote terminal, and a fine-pointing module operably and directly coupleable to a coarse-pointing module of the CubeSat. The fine-pointing module is configured to point the optical transmitter toward the remote terminal with an accuracy range that overlaps with an accuracy range of the coarse-pointing module of the CubeSat so as to establish a communications link between the CubeSat and the remote terminal over a low-Earth-orbit (LEO) distance.

Abstract: A system includes an optical transmitter that outputs an optical signal having a substantially Gaussian waveform and an optical receiver that is optically coupled to the optical transmitter and has an impulse response essentially matching the waveform. The impulse response and waveform preferably match in the time domain. The transmitter and receiver may be average-power-limited, using, for example, an erbium-doped fiber amplifier. To achieve a high signal-to-noise ratio, the waveform may be designed to minimize jitter, sample duration, matching parasitics, and inter-symbol interference (ISI). Such a waveform may be a return-to-zero (RZ) Gaussian or Gaussian-like waveform and may be transmitted in a variety of modulation formats. Further, the system may be used in WDM or TDM systems. A method for characterizing the time domain impulse response of an optical element used in the optical receiver is provided, where the method is optionally optimized using deconvolution and/or cross-correlation techniques.

Abstract: A filter-based method of demodulating differentially encoded phase shift keyed (DPSK) optical signals, such as commonly used binary-DPSK (DBDPSK) and quadrature DPSK (DQPSK) signals, that can achieve optimal receiver sensitivity is described. This approach, which combines filtering and differential phase comparison, can reduce the complexity and cost of DPSK receivers by obviating delay-line interferometer-based demodulation. This can improve receiver stability and reduce size, weight, and power, while maintaining the ability to achieve optimal communications performance.

Abstract: A filter-based method of demodulating differentially encoded phase shift keyed (DPSK) optical signals, such as commonly used binary-DPSK (DBDPSK) and quadrature DPSK (DQPSK) signals, that can achieve optimal receiver sensitivity is described. This approach, which combines filtering and differential phase comparison, can reduce the complexity and cost of DPSK receivers by obviating delay-line interferometer-based demodulation. This can improve receiver stability and reduce size, weight, and power, while maintaining the ability to achieve optimal communications performance.

Abstract: A filter-based method of demodulating differentially encoded phase shift keyed (DPSK) optical signals, such as commonly used binary-DPSK (DBDPSK) and quadrature DPSK (DQPSK) signals, that can achieve optimal receiver sensitivity is described. This approach, which combines filtering and differential phase comparison, can reduce the complexity and cost of DPSK receivers by obviating delay-line interferometer-based demodulation. This can improve receiver stability and reduce size, weight, and power, while maintaining the ability to achieve optimal communications performance.

Abstract: The present invention provides a simple means of demodulating optical signals, e.g. wideband M-ary orthogonal. The demodulator comprises an optical processor and a comparison module. The optical processor transforms M input optical signals into 2 log2(M) intermediary optical signals and the comparison module determines the logical representation of the input data based on log2(M) binary comparisons of the optical power of the intermediary signals. Example embodiments may be reconfigurable to receive optical signals using M-FSK, M-PPM, M-PolSK, and hybrid M-ary orthogonal modulation formats. Example embodiments also offer small size, weight and power consumption for both free-space and fiber optic environments as well as improved receiver sensitivity and reduced electron bandwidth requirements.

Abstract: The present invention addresses the problem of transmitting optical signals with high extinction ratios using low-power drive signals. At present, low-power optical transmitters typically operate with modulation extinction ratios of, at best, about 10 dB. Embodiments of the present invention may achieve extinction ratios exceeding 20 dB using low-power drive signals of under 20 mW at data rates on the order of Gbits/sec. In addition, the modulation may be achieved with both low-power and low-fidelity drive waveforms, enabling conventional and often noisy high-speed, low-power electronics to generate high-extinction, high-fidelity optical waveforms.