The technology employs a state-based power control loop (PCL) architecture to maintain tracking and communication signal-to-noise ratios at suitable levels for optimal tracking performance and data throughput in a free-space optical communication system. Power for a link is adjustable to stay within a functional range of receiving sensors in order to provide continuous service to users. This avoids oversaturation and possible damage to the equipment. The approach can include decreasing or increasing the power to counteract a surge or drop while maintaining a near constant received power at a remote communication device. The system may receive power adjustment feedback from another communication terminal and perform state-based power control according to the received feedback. This can include re-initializing and reacquiring a link with the other communication terminal automatically after loss of power, without human intervention. There may be a default state and discrete states including rain, fade, surge and unstable states.

A first multimode optical fiber carries a mode division multiplexed (MDM) optical signal. The MDM optical signal is transmitted into a second multimode fiber from the first multimode optical fiber. The first and second multimode fibers are coupled via a fiber connector. The lateral offset between the two fibers at the connector is less than 2 μm.

A first multimode optical fiber carries a mode division multiplexed (MDM) optical signal. The MDM optical signal is transmitted into a second multimode fiber from the first multimode optical fiber. The first and second multimode fibers are coupled via a fiber connector. The lateral offset between the two fibers at the connector is less than 2 μm.

A decoder for determining an estimate of a vector of information symbols carried by optical signals propagating along a multi-core fiber in an optical fiber transmission channel according to two or more cores is provided. The decoder is implemented in an optical receiver. The optical signals are encoded using a space-time coding scheme and/or scrambled by at least one scrambling device arranged in the optical fiber transmission channel according to a predefined scrambling function. The decoder comprises a processing unit configured to adaptively: determine, in response to a temporal condition, one or more channel quality indicators from the optical signals; determine a decoding algorithm according to a target quality of service metric and on the one or more channel quality indicators; update the predefined scrambling function and/or the space-time coding scheme depending on the target quality of service metric and on the one or more channel quality indicators. The decoder further comprises a symbol estimation unit configured to determine an estimate of a vector of information symbols by applying the decoding algorithm to the optical signals.

A mode-multiplexing control method, and a transmission apparatus and reception apparatus for the same, the mode-multiplexing control method performed by the transmission apparatus, the mode-multiplexing control method including measuring data traffic, determining a transmission mode count to be used based on the measured data traffic, and transmitting data to a reception apparatus through an optical line in transmission modes corresponding to the determined transmission mode count.

A mode-multiplexing control method, and a transmission apparatus and reception apparatus for the same, the mode-multiplexing control method performed by the transmission apparatus, the mode-multiplexing control method including measuring data traffic, determining a transmission mode count to be used based on the measured data traffic, and transmitting data to a reception apparatus through an optical line in transmission modes corresponding to the determined transmission mode count.

An injection locked transmitter for an optical communication network includes a primary seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one secondary laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the primary seed laser source. The laser injected modulator is configured to receive the primary seed laser source input and the input data stream, and output a laser modulated data stream.

An injection locked transmitter for an optical communication network includes a primary seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one secondary laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the primary seed laser source. The laser injected modulator is configured to receive the primary seed laser source input and the input data stream, and output a laser modulated data stream.

This disclosure describes, among other things, an Optical Communications Module Link Extender (OCML) including embedded Ethernet and PON amplification rather than relying on a separate amplification module for Ethernet and/or PON signals transmitted through the OCML. Providing an OCML that is able to provide the appropriate amplification to transmit both Ethernet and PON signals may be accomplished by using one or more Raman pumps on the signals transmitted in the upstream direction through the OCML (for example, upstream from one or more customer devices to one or more OLTs for PON signals. This OCML configuration may allow for a more cost-effective and efficient system with a smaller footprint than a system that relies on external amplification modules to transmit Ethernet or PON signals.

A method for transmitting a plurality of input streams from a transmitter to a receiver processes each of a plurality of input data streams to generate a plurality of parallel pairs of data streams including an in-phase stream (I) and a quadrature-phase stream (Q) for each of the plurality of input data streams. Each of the plurality of parallel pairs of data streams are modulated with a selected one of at least three prolate spheroidal wave functions, respectively, to generate a plurality of data signals, each of the plurality of data signals associated with one of the plurality of parallel pairs of data streams. A plurality of composite data streams are generated by overlaying at least one data signal of the plurality of data signals in a first data layer with the at least one data signal of the plurality of data signals in a second data layer. The plurality of composite data streams are processed to associate with each of the plurality of composite data streams an orthogonal function to cause each of the plurality of composite data streams to be mutually orthogonal to each other on the link to enable transmission of each of the plurality of the composite data streams on the link at a same time.