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

An optical transmission device includes a first detector, a generator, a second detector, and a controller. The first detector detects optical output power of an optical signal for each channel for input to a Mach-Zehnder unit that has asymmetric optical waveguides. The generator superimposes, based on the detected optical output power for each of the channels, a dither signal onto an optical signal in a specific channel from among the plurality of channels for input to the Mach-Zehnder unit. The second detector detects an amplitude value of the dither signal superimposed onto the optical signal in the specific channel output from the Mach-Zehnder unit. The controller adjusts a phase difference in the Mach-Zehnder unit such that the amplitude value of the dither signal superimposed onto the detected optical signal in the specific channel is less than a predetermined threshold.

Methods, systems, and devices for network communications to reduce optical beat interference (OBI) in upstream communications are described. For example, a fiber node may provide a seed source to injection lock upstream laser diodes. Therefore, upstream communications from each injection locked laser diode may primarily include the wavelength associated with each seed source. The seed sources may be unique to each end device and configured to minimize OBI. That is, the upstream laser diodes may be generic, but the collected seed source may enable upstream communications at varying wavelengths. The end device may provide upstream communications by externally modulating a signal generated by the injection locked laser diode.

High-channel-count optical transceivers can be implemented in photonic integrated circuits (PICs) with shared lasers, splitting the light of each laser between multiple lanes prior to modulation. To reduce waveguide crossings in such PICs, transmitter and self-test functionality may be distributed between separate device layers. Various beneficial transmitter circuitry layouts are disclosed.

Integrated optical filter and photodetectors and methods of fabrication thereof are described herein according to the present disclosure. An example of an integrated optical filter and photodetector described herein includes a substrate, an insulator layer on the substrate, and a semiconductor layer on the insulator layer. An optical filter having a resonant cavity is formed in or on the semiconductor layer. The integrated optical filter and photodetector further includes two first metal fingers and a second metal finger interdigitated between the two first metal fingers on the semiconductor layer forming Schottky barriers. The first metal fingers are constructed from a different metal relative to the second metal finger.

An optical circuit is used with continuous wave signals having different wavelengths at a channel spacing from one another. A portion of the optical circuit is implemented in a photonic integrated circuit. Modulators in a modulation stage modulate the continuous wave signals to produce modulated signals. A multiplexing stage, which can have multiplexing filters, power combiners, or power couplers, multiplexes the continuous wave or modulated signals to produce multiplexed signals. The multiplexing stage may be placed either before or after the modulation stage. One or more polarization rotator and combiner (PRC) devices in a final stage combines the multiplexed signals into an output signal. The output signal has a first set of the different wavelengths at a first polarization and has a second separate set of the different wavelengths at a second polarization orthogonal to the first polarization.

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.

A length calculation unit calculates, based on a transmission time required for an optical signal transmitted from a first optical transmission apparatus to a second optical transmission apparatus through an optical transmission line to be transmitted through the optical transmission line, a length of the optical transmission line. A wavelength dispersion calculation unit calculates a wavelength dispersion per unit length of the optical transmission line based on a wavelength dispersion of the optical signal received by the second optical transmission apparatus and the length of the optical transmission line. A type determination unit determines a type of the optical transmission line based on information indicating a correspondence relationship between a value of the wavelength dispersion per unit length and the type of the optical transmission line and the calculated wavelength dispersion per unit length of the optical transmission line.

Various embodiments are disclosed herein with generally relate to an optical communication system using a photonic lantern. In at least one embodiment, the optical system comprises: an optical transmitter coupled to a signal transmitting path; an optical receiver coupled to a signal receiving path; a photonic lantern, the photonic lantern extending between a first open end and a second open end, the first end comprising an opening to a single multi-mode fiber, and the second end comprising a plurality of single mode fibers that are adiabatically coupled to the multi-mode fiber, the plurality of single-mode fibers includes a single-mode fiber adapted to carry a fundamental optical mode and the remaining single-mode fibers adapted to carry higher-order optical modes, wherein, the single-mode fiber is coupled to the optical transmitting path, the remaining single-mode fibers are coupled to the optical receiving path.

An optical wireless communication system comprising a transmitter apparatus that comprises: an illumination light source configured to output visible light for illumination purposes, and a controller configured to control operation of the illumination light source to produce modulation of the visible light to provide an optical wireless communication signal representing data; a further light source configured to output further light, wherein the controller is configured to control operation of the further light source to produce modulation of the further light to provide a further optical wireless communication signal representing substantially the same data, wherein the visible light and the further light have different wavelengths.