A master oscillator power amplifier comprises a semiconductor laser formed on a substrate and configured to output an optical signal, and a semiconductor optical amplifier (SOA) formed on the substrate. The SOA comprises an optical waveguide having an optically active region, wherein the optical waveguide is configured to expand a mode size of the optical signal along at least two dimensions.

A semiconductor laser may include an active region having a longitudinal axis, a rear facet end and a front facet end. The front facet end emitting an output beam of the semiconductor laser. The semiconductor laser may include a plurality of diffraction gratings positioned along the longitudinal axis of the active region. The plurality of diffraction gratings including a first diffraction grating positioned proximate the rear facet end of the active region and at least one additional diffraction grating positioned longitudinally between the first diffraction grating and the front facet. The first diffraction grating having a first kappa value and the at least one additional diffraction grating having at least a second kappa value, the first kappa value being greater than the second kappa value.

An optical device is provided that includes a waveguide layer and at least one grating structure. A coupling coefficient of the at least one grating structure to a fundamental optical mode supported by the waveguide layer is greater than a coupling coefficient of the at least one grating structure to at least one higher order transverse optical mode supported by the waveguide layer.

An on-chip integrated semiconductor laser structure and a method for preparing the same. The structure includes: an epitaxial structure including a first N contact layer, a first N confinement layer, a first active region, a first P confinement layer, a first P contact layer, an isolation layer, a second N contact layer, a second N confinement layer, a second active region, a second P confinement layer, and a second P contact layer sequentially deposited on a substrate; a first waveguide and a second waveguide; a first optical grating and a second optical grating; and current injection windows.

Embodiments of the present disclosure may relate to a digitized grating that may include a first unit cell that has a first period and a first length, where the first period includes a first grating element width and a first space between adjacent grating elements, and where the first length includes a number of first periods. The digitized grating may further include a second unit cell that has a second period and a second length, where the second period is different than the first period and includes a second grating element width and a second space between adjacent grating elements, and where the second length includes a number of second periods.

The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12° to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95° to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 μm or more.

A laser includes an active region surrounded by first and second waveguide layers. Two or more mask openings are formed within a dielectric layer on a surface parallel to the active region. A refractive grating is formed on the dielectric mask openings and includes three-dimensional grating features spaced apart in the light-propagation direction of the laser. The refractive grating provides modulation of a real part of the effective refractive index of the laser and modulation of the imaginary part is provided by modulation of the current flow through the mask openings.

A distributed feedback laser having a conjugated dendrimer as the active lasing component, and a method for patterning conjugated dendrimers.

What is provided here are: a step of forming a first semiconductor layer on a base member; a step of forming a mask on the first semiconductor layer; a step of etching the first semiconductor layer by using the mask, to thereby form a semiconductor structure; a step of forming a second semiconductor layer in a region abutting on a side surface of the semiconductor structure, said second semiconductor layer having a convex portion abutting to the mask; a convex-portion removing step of removing the convex portion by supplying an etching gas thereto; and a regrown-layer forming step of supplying a material gas onto the semiconductor structure and the second semiconductor layer, to thereby form a regrown layer; wherein the convex-portion removing step and the regrown-layer forming step are executed in a same manufacturing apparatus.

Within examples, a laser includes a first electrode and a second electrode; a first transport layer and a second transport layer that are between the first electrode and the second electrode; a gain layer positioned between the first transport layer and the second transport layer, where the gain layer comprises a material having a Perovskite crystal structure; and a substrate on which the first electrode, the second electrode, the first transport layer, the second transport layer, and the gain layer are formed, where a distributed feedback (DFB) waveguide is formed within the first transport layer, and where the laser is configured such that a current flowing through the gain layer between the first electrode and the second electrode causes the gain layer to emit coherent light. Examples also include methods for fabricating the laser, as well as additional lasers and methods for forming those lasers.