A photonic integrated circuit (PIC) includes various mode field adapters (MFAs), a waveguide, and various contact pads. All the MFAs are on a same facet of the PIC. One MFA of the PIC outputs a first optical signal that is an amplified version of a second optical signal. The waveguide is divided into two waveguide arms and a bend portion to join the two waveguide arms. The waveguide extends between the MFAs such that the second optical signal propagates through the waveguide. Further, each waveguide arm is formed between the contact pads. The second optical signal propagating through the waveguide is amplified based on a current that is injected in the PIC by way of the contact pads.

A laser device is provided which comprises a common waveguide layer and a plurality of laser bodies, wherein each of the laser bodies has an active region configured for generating coherent electromagnetic radiation. The laser bodies are arranged side by side on the common waveguide layer, wherein the laser bodies are directly adjacent to the common waveguide layer. In particular, the laser bodies are configured to be phase-coupled to each other via the waveguide layer during operation of the laser device.

Furthermore, a method for producing such a phase-coupled laser device is provided.

A wavelength tunable light source includes a wavelength tunable laser device and a control device. The wavelength tunable laser device includes: M laser diodes configured to generate laser oscillation to output beams; a multiplexer/demultiplexer configured to multiplex the beams output from the M laser diodes to bifurcate the beams for output; a first semiconductor optical amplifier configured to amplify one output beam of the bifurcated beams to output a first emitted beam; and a second semiconductor optical amplifier configured to amplify another output beam of the bifurcated beams to output a second emitted beam. The control device is configured to perform wavelength switching control on wavelengths of the first emitted beam and the second emitted beam by switching an electric power input to the second semiconductor optical amplifier.

An optical device comprises a light input, a light modulating means and a light output. The optical device further comprises an optical amplification device arranged to amplify light travelling between said light modulating means and said output. The optical amplification device comprises first and second serially connected post SOA (Semiconductor Optical Amplifier) units, each comprising at least one respective serially connected post SOA segment, which device is arranged to vary a light amplification by varying respective SOA bias voltages across said post SOA segments. A total SOA length of the first post SOA unit is relatively longer than a total SOA length of the second post SOA unit, which is relatively shorter. The optical device is arranged to, during operation using a particular operation program, always keep respective SOA bias voltages across each of the post SOA segments of the first post SOA unit at +0.5 V or more.

Systems and methods of undersea optical communication are provided. An undersea optical amplifier assembly can include a water-tight housing and a photonic integrated circuit disposed within the housing. The photonic integrated circuit includes a plurality of optical fiber inputs, each configured to receive an end of a respective optical fiber of a first fiber optic cable bundle, and a plurality of optical fiber outputs. Each optical fiber output corresponds to a respective optical fiber input to form a fiber optic input-output pair, and is configured to receive an end of a respective optical fiber of a second fiber optic cable bundle. The photonic integrated circuit includes an optical amplifier optically coupled to each respective fiber optic input-output pair. The housing includes a first water-tight access port configured to receive the first fiber optic cable bundle, and a second water-tight access port configured to receive a second fiber optic cable bundle.

Described herein are photonic integrated circuits (PICs) comprising a semiconductor optical amplifier (SOA) to output a signal comprising a plurality of wavelengths, a sensor to detect data associated with a power value of each wavelength of the output signal of the SOA, a filter to filter power values of one or more of the wavelengths of the output signal of the SOA, and control circuitry to control the filter to reduce a difference between a pre-determined power value of each filtered wavelength of the output signal of the SOA and the detected power value of each filtered wavelength of the output signal of the SOA.

A wavelength tunable light source includes: a common wavelength filter that has periodic transmission peak wavelengths or reflection peak wavelengths and is commonly used for a plurality of channels; a wavelength tunable filter that is coupled to the common wavelength filter and has a one-input and multiple-output configuration which has a plurality of output ports, and that has a plurality of transmission peak wavelengths corresponding to the plurality of channels at the plurality of output ports; and a plurality of gain media optically coupled to the plurality of output ports of the wavelength tunable filter, wherein a plurality of laser cavities that perform laser oscillation at a plurality of different wavelengths are formed between the common wavelength filter and the plurality of gain media.

An optical amplifier includes an optical amplifier chip that includes a pair of semiconductor optical amplifiers (SOAs), a U-shaped waveguide connecting the pair of SOAS, and two electrodes that respectively correspond to the pair of SOAS and are separated from each other, and a base substrate that includes a common metal wiring connecting the two electrodes, and on which the optical amplifier chip is mounted.

A semiconductor optical amplifier having a 3 dB coupler is described for use in providing an amplified optical data signal to a photonic chip. The semiconductor optical amplifier includes an amplifier die having a signal coupling facet, waveguides terminating at the signal coupling facet, a 3 dB coupler, and a reflector. The 3 dB coupler is optically coupled between the signal coupling facet and the reflector.

Described herein are photonic integrated circuits (PICs) comprising a semiconductor optical amplifier (SOA) to output a signal comprising a plurality of wavelengths, a sensor to detect data associated with a power value of each wavelength of the output signal of the SOA, a filter to filter power values of one or more of the wavelengths of the output signal of the SOA, and control circuitry to control the filter to reduce a difference between a pre-determined power value of each filtered wavelength of the output signal of the SOA and the detected power value of each filtered wavelength of the output signal of the SOA.