Disclosed are a wavelength-selectable laser diode and an optical communication apparatus including the same. The wavelength-selectable laser diode includes a substrate, which includes a gain region, a tuning region spaced apart from the gain region, and a phase adjusting region between the tuning region and the gain region, a waveguide layer on the substrate, a clad layer on the waveguide layer, and gratings disposed on the substrate or the clad layer in the gain region and the tuning region.

A cryogenic optoelectronic data link, comprising a sending module operating at a cryogenic temperature less than 100 K. An ultrasensitive electro-optic modulator, sensitive to input voltages of less than 10 mV, may include at least one optically active layer of graphene, which may be part of a microscale resonator, which in turn may be integrated with an optical waveguide or an optical fiber. The optoelectronic data link enables optical output of weak electrical signals from superconducting or other cryogenic electronic devices in either digital or analog form. The modulator may be integrated on the same chip as the cryogenic electrical devices. A plurality of cryogenic electrical devices may generate a plurality of electrical signals, each coupled to its own modulator. The plurality of modulators may be resonant at different frequencies, and coupled to a common optical output line to transmit a combined wavelength-division-multiplexed (WDM) optical signal.

A computer-implemented method of transmitting through a disordered medium from a transmitter to a receiver an image represented as input coherent electromagnetic radiation, the disordered medium having a transmission matrix comprising a plurality of complex-valued transmission constants that relate said input coherent electromagnetic radiation to output electromagnetic radiation at said receiver, which method comprises the steps of: performing a characterising process on said disordered medium to determine said transmission matrix; using said transmitter to transmit said image through said disordered medium; performing a reconstruction process using said transmission matrix to generate a reconstructed image from the output electromagnetic radiation at said receiver; wherein in said characterisation process the step of determining said transmission matrix comprises: determining said complex-valued transmission constants as real-valued transmission constants by using an approximately linear relationship between said input electromagnetic radiation and said output electromagnetic radiation; and using said real-valued transmission constants to generate and store a version of the transmission matrix; and said reconstruction process comprises the steps of: generating an output signal comprising intensity or amplitude values of said output electromagnetic radiation; generating said reconstructed image by combining said output signal and said version of the transmission matrix in a way that effects a matrix multiplication of an inverse of said transmission matrix and said output signal; and outputting said reconstructed image from said receiver.

A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive user data and provide electrical signals based on the data; and a modulator operable to modulate the optical signal to provide optical subcarriers based on the electrical signals. A first one of the subcarriers carriers carries first TDMA encoded information and second TDMA encoded information, such that the first TDMA encoded information is indicative of a first portion of the data and is carried by the first one of the subcarriers during a first time slot, and the second TDMA encoded information is indicative of a second portion of the data and is carried by the first one of the subcarriers during a second time slot. The first TDMA encoded information is associated with a first node remote from the transmitter and the second TDMA encoded information is associated with a second node remote from the transmitter. A second one of the subcarriers carries third information that is not TDMA encoded, the third information being associated with a third node remote from the transmitter. A receiver and system also are described.

An optical fiber amplification apparatus is disclosed, including an optical receiving port, a first optical output port, a second optical output port, a gain medium, a pump laser, reflection films, and a transmission-reflection film. The pump laser activates a function of the gain medium to amplify an optical signal. A multiplexed optical signal including a first-waveband optical signal and a second-waveband optical signal is incident onto the gain medium. The reflection films enable the multiplexed optical signal to be reflected back and forth in the gain medium. After the first-waveband optical signal reaches a first target gain, the first-waveband optical signal is output from the gain medium to the first optical output port. The second-waveband optical signal is amplified in the gain medium. After the second-waveband optical signal reaches a second target gain, the second-waveband optical signal is output from the gain medium to the second optical output port.

A signal pre-compensation method is provided. In the method, at least one target frequency subband is determined from a plurality of frequency subbands of a first optical signal and an optical signal of the at least one target frequency subband in the first optical signal is demodulated based on the at least one target frequency subband. A first electrical signal is obtained after demodulation, and a pre-compensation parameter is updated based on the at least one target frequency subband, the first electrical signal, and a second electrical signal. Herein the pre-compensation parameter is used to perform signal pre-compensation on the second electrical signal, and the first optical signal is generated after the pre-compensation is performed on the second electrical signal.

A system for controlling a pulsed laser diode includes a power source configured to supply power to the pulsed laser diode and at least one driving branch between the power source and the pulsed laser diode. The at least one driving branch is configured to control power delivery from the power source to the pulsed laser diode. The at least one driving branch is connected to a cathode of the pulsed laser diode.

A wavelength division multiplexing filter comprises: a first multi-order Mach-Zehnder interferometer comprising a plurality of first-order Mach-Zehnder interferometers, and a second multi-order Mach-Zehnder interferometer comprising a plurality of first-order Mach-Zehnder interferometers; wherein the first multi-order Mach-Zehnder interferometer and the second multi-order Mach-Zehnder interferometer are included in a group of multiple multi-order Mach-Zehnder interferometers arranged within a binary tree arrangement, the binary tree arrangement comprising: a first set of a plurality of multi-order Mach-Zehnder interferometers, the first set including the first multi-order Mach-Zehnder interferometer, and having an associated spectral response with a first spacing between adjacent passbands, and a second set of at least twice as many multi-order Mach-Zehnder interferometers as in the first set, the second set including the second multi-order Mach-Zehnder interferometer, and having an associated spectral response with a second spacing between adjacent passbands that is twice the first spacing.

An interconnect transceiver for transmitting and receiving optical signals, comprising an electronics module with a transceiver engine, and a photonics module with a laser source, a modulator, a photodetector to monitor the laser, one to receive an external optical signal, and a controller to operate the laser source and the laser source modulator, an electronic switch having two states is proposed. The first state is to allow monitoring of the modulated laser source by the transceiver engine, so as to acquire a reference set of operating parameters, and the second state is where a signal from the modulated laser source is directed to the controller, such as to allow real-time control of the source of the transmitting laser and modulator by the controller.

In a system for converting digital data into a modulated optical signal, an electrically controllable device, including a modulator having one or more actuating electrodes, provides an analog-modulated optical signal that is modulated in response to output data bits of a digital-to-digital mapping. A digital-to-digital conversion provides the mapping of input data words to the output data bits. The mapping enables adjustments to correct for non-linearities and other undesirable characteristics, thereby improving signal quality.