Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, an optical communication system includes a primary transceiver, a component, and secondary transceivers. The primary transceiver is operable to supply first optical subcarriers to an optical communication path, the first optical subcarriers being amplitude modulated at a first frequency to carry first control information and amplitude modulated at a second frequency to carry second control information. The component is operable to be coupled to the optical communication path and includes circuitry operable to detect the first control information. The secondary transceivers are coupled to a terminal end of the optical communication path. At least one of the secondary transceivers is operable to detect the second control information and block the first control information.

An object is to be capable of housing an optical fiber that connects between components not to exceed a bending limit of the optical fiber in a housing of a pluggable optical module. A pluggable electric connector (11) is configured to be insertable into and removable from an optical communication apparatus (93). An optical output module (12) outputs an optical signal (LS1) and a local oscillation light (LO). An optical reception module (13) outputs a communication data signal (DAT) generated by demodulating using the local oscillation light (LO). A pluggable optical receptor (15) is configured in such a manner that optical fibers are insertable thereinto and removable therefrom. A first optical fiber (F11) is connected between the optical output module (12) and the pluggable optical receptor (15). A second optical fiber (F12) is connected between the optical output module (12) and the optical reception module (13). A third optical fiber (F13) is connected between the optical reception module (13) and the pluggable optical receptor (15). Optical fiber housing means winds extra lengths of the first to third optical fibers (F11 to F13) around a guide.

Provided is a coherent detection implementing apparatus, system and method. The apparatus includes: a first transceiver unit, configured to send an optical signal in a first direction to a second device, wherein the optical signal in the first direction includes a direct current optical signal with a first wavelength and a modulated optical signal with a second wavelength; and configured to receive an optical signal in a second direction from the second device; and a first coherent receiver, connected with the first transceiver unit, and configured to take a part of the direct current optical signal with the first wavelength in the optical signal in the first direction as a Local Oscillator (LO) light for coherent reception, perform coherent frequency mixing between the LO light and the optical signal in the second direction, and demodulate the optical signal in the second direction.

A Field Programmable Gate Array (“FPGA”) transmitter reliability directly drives an optical modulator. Each time the FPGA is powered up, the transmitters are aligned using optical feedback for coarse and fine alignments. The fine alignment may be executed using a built-in transmitter phase interpolator Parts-Per-Million (“PPM”) controller.

An apparatus includes an input receiving a modulated optical data signal having components of at least first and second polarizations, a first optical detector receiving the data signal, the first optical detector being first polarization-selective or first polarization-sensitive, passing components of the data signal having the second polarization, and outputting a first electrical signal, a second optical detector coupled to the first optical detector to receive the components of the data signal having the second polarization, and outputting a second electrical signal, and a processor applying a Kramers-Kronig process to the first and second electrical signals, and outputting the data signal using the Kramers-Kronig processed first and second electrical signals. A combiner is connected between the input and the first optical detector and combines the data signal with an unmodulated optical signal such that the unmodulated optical signal serves as a Kramers-Kronig carrier for the first and second polarizations.

An example system includes a hub transceiver and a plurality of edge transceivers. The hub transceiver is operable to transmit, over a first communications channel, a first message to each of the edge transceivers concurrently, including an indication of available network resources on an optical communications network. Each of the edge transceiver is operable to transmit, transmit, over a second communications channel, a respective second message to the hub transceiver including an indication of a respective subset of the available network resources selected by the edge transceiver for use in communicating over the optical communications network. Further, the edge transceiver is operable to receive, from the hub transceiver, a third message acknowledging receipt of a selection and a fourth message confirming an assignment of the selected subset of the available network resources to the edge transceiver.

An object is to be capable of housing an optical fiber that connects between components not to exceed a bending limit of the optical fiber in a housing of a pluggable optical module. A pluggable electric connector (11) is configured to be insertable into and removable from an optical communication apparatus (93). An optical output module (12) outputs an optical signal (LS1) and a local oscillation light (LO). An optical reception module (13) outputs a communication data signal (DAT) generated by demodulating using the local oscillation light (LO). A pluggable optical receptor (15) is configured in such a manner that optical fibers are insertable thereinto and removable therefrom. A first optical fiber (F11) is connected between the optical output module (12) and the pluggable optical receptor (15). A second optical fiber (F12) is connected between the optical output module (12) and the optical reception module (13). A third optical fiber (F13) is connected between the optical reception module (13) and the pluggable optical receptor (15). Optical fiber housing means winds extra lengths of the first to third optical fibers (F11 to F13) around a guide.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS) systems, methods, and structures that advantageously sense/monitor intra-data center operations using self-coherent detection. Advantageously, sensing signal(s) and data signal(s) are optically multiplexed such that the sensing signal(s) are generated and detected using the same optoelectronic components as data generation and detection while requiring only minimal changes to transponder arrangements and no additional bandwidth to digital-to-analog converters (DAC) or analog-to-digital converters (ADC).

A coherent optical transmitter is in operable communication with an optical fiber an includes a plurality of analog-to-digital converters (ADCs) configured to (i) receive a plurality of radio frequency analog input signals, respectively, and (ii) convert the received plurality of RF analog input signals into a plurality of respective digital data streams. The transmitter further includes a source laser configured to output at least two orthogonal polarization component signals, and at least two polarization modulators configured to modulate (i) an in-phase portion output from a first ADC, (ii) an in-quadrature portion output from a second ADC, and (iii) one polarization component signal of the at least two orthogonal polarization component signals. The transmitter further includes a polarization beam combiner configured to (i) multiplex the respective outputs of the at least two polarization modulators, and (ii) transmit the multiplexed output from the polarization beam combiner to the optical fiber.

Optical network systems and components are disclosed, including a transmitter comprising a digital signal processor that receives data; circuitry that generate a plurality of electrical signals based on the data; a plurality of filters, each of which receiving a corresponding one of the plurality of electrical signals, a plurality of roll-off factors being associated with a respective one of the plurality of filters; a plurality of DACs that receive outputs from the digital signal processor, the outputs being indicative of outputs from the plurality of filters; a laser that supplies light; and a modulator that receives the light and outputs from the DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.