A disclosed semiconductor laser device includes a distributed feedback portion serving as a light-emittable active region the distributed feedback portion having a diffraction grating; and a distributed reflective portion serving as a passive reflective mirror, the distributed reflective portion having a diffraction grating, wherein the distributed feedback portion includes a first region adjacent to the distributed reflective portion and having a diffraction grating having a predetermined standard period, a phase shift region adjacent to the first region, the phase shift region being longer by twice or more than the standard period, and a second region adjacent to an opposite side to the first region of the phase shift region and having a diffraction grating with the standard period, and the phase shift region optically changes a phase of laser beam between the first region and the second region.

There is disclosed in one example a communication system, including: a data transmission interface; and a wavelength division multiplexing (WDM) silicon laser source to provide modulated data on a carrier laser via the data transmission interface, the WDM laser including a single laser cavity to generate an internally multiplexed multi-wavelength laser, the single laser cavity including a filter having a first grating period to generate a first wavelength and a second grating period to generate a second wavelength, the second grating period superimposed on the first grating period.

Various disclosed embodiments provide illustrative interferometers, optical phase locked loops, laser systems, interferometry methods, and phase locked loop methods. In illustrative embodiments, light from a laser is split into a first arm and a second arm. Light in an arm chosen from the first arm and the second arm is time delayed. The light in the first arm is split into third, fourth, and fifth arms. The light in the second arm is split into sixth, seventh, and eighth arms. Light in the seventh and eighth arms is phase shifted relative to light in the sixth arm. Light in the third, fourth, and fifth arms is combined with light in the sixth arm and phase shifted light in the seventh and eighth arms, respectively. A frequency correction signal for the laser is generated.

A tunable laser that includes an array of parallel optical amplifiers is described. The laser may also include an intracavity NM coupler that couples power between a cavity mirror and the array of parallel optical amplifiers. Phase adjusters in optical paths between the NM coupler and the optical amplifiers can be used to adjust an amount of power output from M1 ports of the NM coupler. A tunable wavelength filter is incorporated in the laser cavity to select a lasing wavelength.

A process of forming a semiconductor optical device is disclosed. The semiconductor optical device provides a waveguide structure accompanied with a heater for varying a temperature of the waveguide structure. The process includes steps of: (a) forming a striped mask on a semiconductor substrate; (b) selectively growing a dummy layer on the semiconductor substrate; (c) removing the patterned mask; (d) burying the dummy layer by a supplemental layer; (e) exposing a portion of the dummy layer by etching a portion of the supplemental layer; (f) and removing the dummy layer by immersing the dummy layer within a solution that shows an etching rate for the dummy layer enough faster than an etching rate for the supplemental layer and the substrate so as to leave a void in a region the dummy layer had existed.

Provided is a distributed feed back semiconductor laser including a phase shift part capable of obtaining an excellent single-mode yield and a high luminous efficiency. A diffraction grating (105) is formed so as to extend in a guiding direction of a resonator between an end surface at which a low reflective film (111) is formed and an end surface at which a high reflective film (110) is formed. In diffraction grating (105) a plurality of phase shift parts (106) that discontinuously change a phase of the diffraction grating (105) in a predetermined range separated from the end surface at which the low reflective film (111) is formed are disposed.

A light emitting device, an optical module and a manufacturing method thereof are disclosed. According to an example of the disclosure, the light emitting device may comprise an optical waveguide chip, a light emitting chip and a grating between the light emitting chip and the optical waveguide chip. The light emitting chip may emit laser light. The grating may couple the laser light emitted from the active layer into the optical waveguide chip in a way that the laser light is output along a length direction of the optical waveguide chip.

Consistent with the present disclosure, an output of a seed laser is split by a series of first coupler stages and each split portion is provided to a respective laser in an array of secondary lasers to realized injection locking of the laser array. Undesired light output from the secondary laser array back to the seed laser is monitored and the phase of such light is adjusted so that such light is subject to destructive interference and its power is minimized. Accordingly, light output from the secondary laser array back to the seed laser does not degrade the performance of the seed laser. On the other hand, light intended for output from the secondary laser array is combined through a second series of coupler stages and monitored at each stage. The phase of the output of each laser in the array is controlled to equal or be aligned with one another such that laser array outputs constructively interfere with one another. As a result, the combined output power is maximized.

A ring-cavity surface emitting quantum cascade laser (RCSE-QCL) may include a ring-shaped active region having first and second opposing facets. One of the first and second opposing facets may define a radiation emitting facet. The RCSE-QCL may also include a ring-shaped phase shifter aligned with the radiation emitting facet and having a spiraled surface.

A ring-cavity surface emitting quantum cascade laser (RCSE-QCL) may include a ring-shaped active region having first and second opposing facets. One of the first and second opposing facets may define a radiation emitting facet. The RCSE-QCL may also include a ring-shaped phase shifter aligned with the radiation emitting facet and having a spiraled surface.