An optical network element for a hardware configured optical network includes a first optical port that receives an input optical signal comprising receive control information from the hardware configured optical network. A demodulator optically coupled to the first optical port decodes the receive control information for configuring the optical network element. A modulator having an electrical modulation input that receives transmit control information imparts a modulation onto an optical carrier thereby generating a transmit optical control signal representing the transmit control information. A second optical port transmits the transmit optical control signal representing the transmit control information to the hardware configured optical network.

A downhole tool apparatus is disclosed that includes an input fiber optic cable coupled to an electro-optic modulator. The input fiber optic cable propagates first and second actively orthogonally polarized light beams. The electro-optic modulator modulates the first and second actively orthogonally polarized light beams in response to a measurement data stream (e.g., telemetry data). A single light beam comprising the modulated first and second actively orthogonally polarized light beams is propagated over an output fiber optic cable so that the modulated first and the second actively orthogonally polarized light beams propagate the same data through the output fiber optic cable. Recovery circuitry coupled to the single light beam is then used to detect, demodulate, and decode the original measurement data stream.

An optical network element for a hardware configured optical network includes a first optical port that receives an input optical signal comprising receive control information from the hardware configured optical network. A demodulator optically coupled to the first optical port decodes the receive control information for configuring the optical network element. A modulator having an electrical modulation input that receives transmit control information imparts a modulation onto an optical carrier thereby generating a transmit optical control signal representing the transmit control information. A second optical port transmits the transmit optical control signal representing the transmit control information to the hardware configured optical network.

There is provided a receiving device including a receiver configured to receive a signal including at least data information and control information; a monitor configured to monitor the control information included in the signal received by the receiver; and a controller configured to control the monitor to start monitoring the control information when a strength of the signal is equal to or lower than a predetermined value.

In some embodiments, an apparatus includes a first optical transceiver. The first optical transceiver includes a set of optical transmitters, an optical multiplexer operatively coupled to the set of optical transmitters, and a variable optical attenuator operatively coupled to the optical multiplexer. The variable optical attenuator is configured to receive a control signal from a controller of the first optical transceiver and modulate a signal representing control information with an output from the optical multiplexer. The control information is associated with the control signal and for a second optical transceiver operatively coupled to the first optical transceiver.

An optical network element for a hardware configured optical network includes a first optical port that receives an input optical signal comprising receive control information from the hardware configured optical network. A demodulator optically coupled to the first optical port decodes the receive control information for configuring the optical network element. A modulator having an electrical modulation input that receives transmit control information imparts a modulation onto an optical carrier thereby generating a transmit optical control signal representing the transmit control information. A second optical port transmits the transmit optical control signal representing the transmit control information to the hardware configured optical network.

The present disclosure provides an optical module comprising: a photoelectric conversion unit, a first demodulation circuit, and a second demodulation circuit; the first demodulation circuit and the second demodulation circuit are respectively connected to the photoelectric conversion unit; the photoelectric conversion unit is configured to convert the received optical signal into an electrical signal; the first demodulation circuit is configured to demodulate an electrical signal converted by the photoelectric conversion unit and generate a high-frequency electrical signal; the second demodulation circuit is configured to demodulate an electrical signal converted by the photoelectric conversion unit and generate a low-frequency electrical signal.

A receiving device receives a received signal in which a data signal, modulated by using a phase modulation method, and a pilot signal are time-multiplexed. The receiving device includes a synchronizing circuit that synchronizes the phase of the received signal. The synchronizing circuit extracts a pilot signal from the received signal. The synchronizing circuit estimates a phase error by comparing the extracted pilot signal and a predetermined pattern. The synchronizing circuit conducts phase rotation on constellation points of the received signal in accordance with the reference phase, obtained from the phase error, and the phase in the modulation method related to the received signal. The synchronizing circuit estimates a phase estimate value of the received signal in accordance with the constellation points, on which phase rotation has been conducted. The synchronizing circuit compensates for a phase error of the received signal in accordance with the phase estimate value.

Methods, circuits and active optical cable assemblies for simultaneous transmission of low-speed optical data and high-speed optical data over an optical fiber link are disclosed. In one embodiment, a method of optical communication includes controlling a laser such that an output of the laser transmits high-speed optical data at a first bit rate, and modulating an amplitude of the output of the laser such that the laser transmits low-speed optical data at a second bit rate simultaneously with the high-speed optical data. In another embodiment, a circuit for providing optical communication includes a laser and a laser driver circuit that digitally modulates an output of the laser to transmit high-speed optical data at a first bit rate. The circuit further includes an amplitude modulation circuit that modulates an amplitude of the laser to transmit low-speed optical data at a second bit rate simultaneously with the high-speed optical data.

A multifunctional laser driving circuit, and an optical module and method of using the same, are disclosed. The circuit combines first and second optical signals having different functions to form a compound signal, and switches among the first optical signal, second optical signal and compound signal by enabling or disabling first and second laser drivers corresponding to the first and second optical signals. The circuit can provide functions to optical modules, including converting an electrical data signal into an optical data signal; converting an electrical line monitoring signal into an optical line monitoring signal; combining the optical data and line monitoring signals and synchronously transmitting them to a fiber; and providing an OTDR function. Relative to using external OTDR tools to detect line faults, the present circuit and method enables simple line connection, timely detection of lines faults, and low costs of implementation.