An optical semiconductor device includes a semiconductor multilayer structure, an active region interposed between a first facet on a light emitting side and a second facet opposing to the first facet, and a first electrode layer provided on a top of the semiconductor multilayer structure and a second electrode layer provided on a bottom of the semiconductor multilayer structure; and an electrical connection region connected to at least one of the first electrode layer and the second electrode layer of the optical semiconductor device and used for injecting a current to the active region, and > and >0 are satisfied where is the contact area included in a half region on the first facet side in a top area of the optical semiconductor device and is the contact area included in a half region on the second facet side.

A semiconductor laser device is provided with a semiconductor layer including an active layer and a plurality of cladding layers sandwiching the active layer. The active layer includes a stripe-shaped active region, a pair of first refractive index regions and a pair of second refractive index regions sandwiching the active layer and the pair of first refractive index regions. When is the laser oscillation wavelength, n.sub.a is the effective refractive index of the active region, n.sub.c is the effective refractive index of the first refractive index regions, n.sub.t is the effective refractive index of the second refractive index regions, w is the width of the active region, and m is a positive integer, the semiconductor laser device satisfies n.sub.a>n.sub.t>n.sub.c, and the conditions of equations (5), (8) and (9).

A vertical cavity surface emitting laser (VCSEL) may include a top contact, wherein the top contact is associated with a particular shape, and wherein the particular shape is a toothed shape with a particular quantity of teeth. The VCSEL may include at least one implanted region. The VCSEL may include at least one top contact segment.

Provided are a laser device and a method of transforming laser spectrum, which provide a laser frequency stabilization and significant narrowing a laser spectrum. A laser device includes at least one multiple longitudinal mode laser (L) for generating a laser light having a spectrum of multiple longitudinal modes; at least one high quality factor (high-Q) microresonator (M) optically feedback coupled to the at least one multiple longitudinal mode laser (L); and a tuner (TU) for tuning the spectrum of multiple longitudinal modes of the laser light. The laser device is configured to output an output laser light having an output spectrum with at least one dominant longitudinal laser mode each at a reduced linewidth of the dominant longitudinal laser mode. The laser device allows increasing an emission power of a narrow linewidth lasing without an additional amplification while keeping a compact size of a device with a limited number of optical elements.

A laser diode vertical epitaxial structure, comprising a transverse waveguide comprising an active layer between an n-type semiconductor layer and a p-type semiconductor layer wherein the transverse waveguide is bounded by a lower index n-cladding layer on an n-side of the transverse waveguide and a lower index p-cladding layer on a p-side of the transverse waveguide, a lateral waveguide that is orthogonal to the transverse waveguide, wherein the lateral waveguide is bounded in a longitudinal direction at a first end by a facet coated with a high reflector (HR) coating and at a second end by a facet coated with a partial reflector (PR) coating and a higher order mode suppression layer (HOMSL) disposed adjacent to at least one lateral side of the lateral waveguide and that extends in a longitudinal direction.

A segmented VCSEL array having a plurality of individually addressable segments, each segment comprising one or more VCSELs. In some cases, at least two of the plurality of individually addressable segments may be driven in combination. The plurality of individually addressable segments, in some embodiments, may be centered around the same central point. An optical element may be used in conjunction with the segmented VCSEL array, and in some cases may be aligned to the central point. The optical element may be configured such that light passing therethrough may be directed according to which of the plurality of individually addressable segments is activated. In some embodiments, the optical element is a grating or diffractive optical element. The grating or diffractive optical element could be patterned with optical segments that each correspond to at least one the plurality of individually addressable segments.

Systems and methods disclosed herein include an imaging system that may include a laser diode source; an objective lens positioned to direct a focus tracking beam from the light source onto a location in a sample container and to receive the focus tracking beam reflected from the sample; and an image sensor that may include a plurality of pixel locations to receive focus tracking beam that is reflected off of the location in the sample container, where the reflected focus tracking beam may create a spot on the image sensor. Some examples may further include a laser diode light source that may be operated at a power level that is above a power level for operation at an Amplified Spontaneous Emission (ASE) mode, but below a power level for single mode operation.

A semiconductor laser is for generating colored light. The semiconductor laser oscillates in a longitudinal multimode. A width of a wavelength band with an intensity equal to or more than 20 dB relative to a peak intensity in a spectrum distribution of output light is equal to or less than 15 nm. A light source device may include The semiconductor laser; a wavelength estimating device configured to estimate a wavelength of light from the semiconductor laser; and an emission-light intensity setting unit configured to set an emission light intensity of the semiconductor laser in accordance with an estimation result by the wavelength estimating device.

A monolithic integrated semiconductor random laser composed of a gain region and random feedback region, comprising: a substrate, a lower confinement layer on the substrate, an active layer on the lower confinement layer, an upper confinement layer on the active layer, a strip-shaped waveguide layer longitudinally made in middle of the upper confinement layer, a P.sup.+ electrode layer divided into two segments by an isolation groove and made on the waveguide layer, and an N.sup.+ electrode layer on a back face of the lower confinement layer. The two segments of the P.sup.+ electrode layer correspond respectively to the gain region and the random feedback region. The random feedback region uses a doped waveguide to randomly feed back light emitted and amplified by the gain region. As a result, random laser is emitted. Frequency and intensity of laser emitted by semiconductor laser are random, and a monolithic integration structure is used, making semiconductor laser be light, small, stable in performance, and strong in integration.

A semiconductor laser is disclosed. Trim loss region is provided in inner ridge region of surface of transmission layer facing away from substrate, blind hole is provided in trim loss region, and distance from bottom surface of blind hole to surface of second cladding layer facing to substrate is smaller than evanescent wave length in transmission layer. Blind hole can affect optical field characteristics of light transmission in semiconductor laser by affecting evanescent wave. A method for fabricating a semiconductor laser is also provided.