A QCL may include a substrate, and a semiconductor layer adjacent the substrate. The semiconductor layer may define branch active regions, and a stem region coupled to output ends of the branch active regions. Each branch active region may have a number of stages less than 30.

An optical resonator of wavelength beam combining type, includes: a laser diode array having a plurality of laser elements arranged along a predetermined direction and configured to emit light beams having wavelengths different from one another; a diffraction grating that diffracts the light beam emitted from each of the laser elements at a diffraction angle corresponding to the wavelength of the light beam; an output coupler that reflects a part of the light beam diffracted by the diffraction grating toward each of the laser elements; and an optical system provided between the laser diode array and the diffraction grating and configured to align the light beams emitted from the laser elements with one another; wherein the optical system includes a first lens element having a negative power only in the predetermined direction and a second lens element having a positive power only in the predetermined direction.

Provided is a tunable laser source including a plurality of optical waveguides, at least three optical resonators provided between the plurality of optical waveguides and optically coupled to the plurality of optical waveguides, the at least three optical resonators having different lengths, and at least one optical amplifier provided on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer.

An integrated photonic device having an array of two or more semiconductor optical amplifiers includes a first semiconductor optical amplifier, which has a first gain region and a second gain region connected by a first connecting waveguide, and a second semiconductor optical amplifier, which is provided in parallel with the first semiconductor optical amplifier and has a third gain region and a fourth gain region connected by a second connecting waveguide. The first gain region and the second gain region are provided on an outer side of the third gain region and the fourth gain region. The first connecting waveguide is configured to connect the first gain region and the second gain region on the outer side of the second connecting waveguide.

A device comprises three elements. The first element, comprising an optical gain structure and a laser cavity mirror structure, couples light to the second element, comprising a phase tuner. The second element couples phase tuned light to the third element. The third element, comprising an optical resonator with first and second coupler/splitter structures, provides a primary optical output from the second coupler/splitter structure. Light coupled into the optical resonator through the first coupler/splitter structure and then coupled out of the optical resonator though the first coupler/splitter structure is injected back into the optical gain structure through the second element. Light coupled out of the optical resonator through the second coupler/splitter structure is provided as the primary optical output. Characteristic of the coupler/splitter structures and the optical resonator are selected such that the light injected back into the optical gain structure reduces linewidth, and noise in primary optical output is suppressed.

A multi-channel laser source, including: a bus waveguide coupled, at an output end of the bus waveguide, to an output of the multi-channel laser source; a first semiconductor optical amplifier; a first back mirror; a first wavelength-dependent coupler, having a first resonant wavelength, on the bus waveguide; a second semiconductor optical amplifier; a second back mirror; and a second wavelength-dependent coupler, on the bus waveguide, having a second resonant wavelength, different from the first resonant wavelength. In some embodiments the first semiconductor optical amplifier is coupled to the bus waveguide by the first wavelength-dependent coupler, which is nearer to the output end of the bus waveguide than the second wavelength-dependent coupler, the second semiconductor optical amplifier is coupled to the bus waveguide by the second wavelength-dependent coupler, and the first wavelength-dependent coupler is configured to transmit light, at the second resonant wavelength, along the bus waveguide.

Provided is a laser oscillation device including; a plurality of semiconductor laser diodes (1a to 1e); optical component (5) that directs a plurality of laser beams emitted from the plurality of semiconductor laser diodes in a specific direction to generate a superimposed laser beam including the plurality of laser beams and propagating in the specific direction; and optical switching element (130) that receives the superimposed laser beam from optical component (5). The superimposed laser beam has a plurality of wavelengths.

The invention relates to a radiation-emitting semiconductor chip having the following features:—a semiconductor body including an active region which, during operation, generates electromagnetic radiation and is arranged in a resonator, —at least one recess in the semiconductor body, which recess completely penetrates the active region, wherein—the recess has a first lateral face and a second lateral face opposite the first lateral face, and—the first lateral face has a first coating which specifies a reflectivity for the electromagnetic radiation of the active region, and/or—the second lateral face has a second coating which specifies a reflectivity for the electromagnetic radiation of the active region. The invention further relates to a method for producing such a semiconductor chip.

Aspects of the present disclosure describe planar lightwave circuit systems, methods and structures including a resonant mirror assembly having cascaded resonators that provide or otherwise facilitate the control of the transmissivity/reflectivity of a planar lightwave circuit (PLC)—or portion thereof—over a range of 0% to substantially 100%.

A system and method for stabilizing and combining multiple emitted beams into a single system using both WBC and WDM techniques.