A microcomputer 202 is coupled to a SFP module 101 via control signal lines 112 to 114. The microcomputer 202 monitors control signals transmitted on the control signal lines 112 to 114, and acquires, based on the result of monitoring, the condition of the SFP module 101 from a ROM 151 at a timing when a protocol chip 102 is not accessing the SFP module 101.

An optical communication network includes a downstream optical transceiver. The downstream optical transceiver includes at least one coherent optical transmitter configured to transmit a downstream coherent dual-band optical signal having a left-side band portion, a right-side band portion, and a central optical carrier disposed within a guard band between the left-side band portion and the right-side band portion. The network further includes an optical transport medium configured to carry the downstream coherent dual-band optical signal from the downstream optical transceiver. The network further includes at least one modem device operably coupled to the optical transport medium and configured to receive the downstream coherent dual-band optical signal from the optical transport medium. The at least one modem device includes a downstream coherent optical receiver, and a first slave laser injection locked to a frequency of the central optical carrier.

An asymmetric coherent receiver includes an optical front end configured to split a received optical signal into two paths, wherein the split received optical signal experiences a different optical transfer function in one of the two paths; two photodetectors each configured to detect power one of the split received optical signals in each of the two paths to obtain corresponding electrical signals; and circuitry configured to perform electrical domain extraction of information of each of the corresponding electrical signals from the two paths, wherein the different optical transfer function provides additional information utilized in optical field reconstruction via direct detection.

A method of encoding quantum information on one or several degrees of freedom of coherent states of photons of a baseband input optical signal, a quantum transmitter, and a computer-readable medium. The quantum transmitter comprises a modulator configured to encode quantum information on one or several degrees of freedom of coherent states of photons of a baseband input optical signal using sideband modulation of the baseband optical input signal.

A hyperspectral radiometer may comprise one or more antennas, a electro-optical modulator modulating the received RF signal onto an optical carrier to generate a modulated signal having at least one sideband; a filter filtering the modulated signal to pass the sideband to a photodetector; and a photodetector producing an electrical signal from which information of the RF signal can be extracted. In some examples, the optical sideband may be spatially dispersed to provide a plurality of spatially separate optical components to the photodetector, where the spatially separate optical components having different frequencies and correspond to different frequencies of the received RF signal. In some examples, the passed sideband may be mixed with an optical beam having a frequency offset from the optical carrier to form a combined beam having at least one optical signal component having a beat frequency from which information of the RF signal can be extracted.

An asymmetric coherent receiver includes an optical front end configured to split a received optical signal into two paths, wherein the split received optical signal experiences a different optical transfer function in one of the two paths; two photodetectors each configured to detect power one of the split received optical signals in each of the two paths to obtain corresponding electrical signals; and circuitry configured to perform electrical domain extraction of information of each of the corresponding electrical signals from the two paths, wherein the different optical transfer function provides additional information utilized in optical field reconstruction via direct detection.

Systems, methods, and computer-readable media are provided for signaling the presence of a fault in a multi-band optical network or other communication system. In response to a detected fault in a multi-band communication system impacting a specific band of the multi-band communication system, a method, according to one implementation, may include a step of creating a fault signal corresponding to the detected fault. The method may also include the step of conveying the fault signal to at least one of an upstream controller and a downstream controller of the multi-band communication system to trigger an action for handling the fault on the specific band. The action may be handled independently of other actions associated with one or more other bands of the multi-band communication system.

A hyperspectral radiometer may comprise one or more antennas, a electro-optical modulator modulating the received RF signal onto an optical carrier to generate a modulated signal having at least one sideband; a filter filtering the modulated signal to pass the sideband to a photodetector; and a photodetector producing an electrical signal from which information of the RF signal can be extracted. In some examples, the optical sideband may be spatially dispersed to provide a plurality of spatially separate optical components to the photodetector, where the spatially separate optical components having different frequencies and correspond to different frequencies of the received RF signal. In some examples, the passed sideband may be mixed with an optical beam having a frequency offset from the optical carrier to form a combined beam having at least one optical signal component having a beat frequency from which information of the RF signal can be extracted.

A photonic processor includes a modulator, an optical filter, and a polarization combiner. The modulator is configured to receive an electronic signal, first optical control signal, and first optical operating signal, the first optical operating signal received from an optical source circuit on a first path having a first length, the first optical control signal received from an optical control circuit on the first path; modulate the first optical operating signal using the electronic signal to provide an intensity-modulated optical operating signal comprising a first optical operating carrier, first sideband, and second sideband; and modulate the first optical control signal using the electronic signal to provide an intensity-modulated control signal comprising a first optical control carrier. The optical filter is configured to extract the first optical operating carrier and first sideband from the intensity-modulated optical operating signal and provide the second sideband and the control carrier.

A method for operating an optical modulator includes receiving a narrowband radio frequency (“RF”) signal. The method further including, responsive to receiving the narrowband RF signal, modulating the narrowband RF signal using a double sideband suppressed carrier (“DSBSC”) modulation scheme to generate a DSBSC optical signal. The method further including transmitting the DSBSC optical signal to an optical transmitter.