Disclosed is a semiconductor laser with a substrate mode suppression layer, comprising a substrate, a first limiting layer, a first waveguide layer, an active layer, a second waveguide layer, an electron blocking layer, and a second limiting layer sequentially stacked from bottom to top. A Si/C concentration ratio of an element Si to an element C of the substrate mode suppression layer?that of the first sub-limiting layer?that of the second sub-limiting layer. An In/Al concentration ratio of an element In to an element Al of the substrate mode suppression layer?that of the first sub-limiting layer?that of the second sub-limiting layer. An H/C concentration ratio of an element H to an element C of the substrate mode suppression layer?that of the second sub-limiting layer?that of the first sub-limiting layer.

A vertical cavity surface emitting laser (VCSEL) may include an active region (e.g., one or more quantum wells) and a chirped pattern reflector. The active region may be configured to be electrically pumped such that the active region generates light having a fundamental mode and a higher order mode. The chirped pattern reflector may include a first portion presenting to the active region as a first portion of an effective mirror having a concave shape and a second portion presenting to the active region as a second portion of the effective mirror having a convex shape.

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.

Disclosed is a semiconductor laser with a substrate mode suppression layer, comprising a substrate, a first limiting layer, a first waveguide layer, an active layer, a second waveguide layer, an electron blocking layer, and a second limiting layer sequentially stacked from bottom to top. A Si/C concentration ratio of an element Si to an element C of the substrate mode suppression layer?that of the first sub-limiting layer?that of the second sub-limiting layer. An In/Al concentration ratio of an element In to an element Al of the substrate mode suppression layer?that of the first sub-limiting layer?that of the second sub-limiting layer. An H/C concentration ratio of an element H to an element C of the substrate mode suppression layer?that of the second sub-limiting layer?that of the first sub-limiting layer.

A spectrometer device may include a first QCL configured to operate in a frequency comb mode with spectrally equidistant modes with stable relative phase, a power supply coupled to the first QCL, and a controller coupled to the power supply. The first QCL may include different active region layers based on a vertical transition. The first QCL may be configured to provide a comb output having a cumulative flat gain profile and reduced dispersion refractive index profile in a broad range of driving conditions. The spectrometer device may include a sample cell configured to receive the comb output.

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 system and method for scanning the wavelength of an external cavity laser uses synchronized angular motions of two mirrors. By adjusting the angular motions in a selected ratio, it is possible to change the lasing wavelength of the cavity without mode-hops. The mode-hop free ratio of angular motions is determined by simultaneously satisfying the conditions of wavelength selected by diffraction angle from a diffraction grating, and the length of the external cavity.

A hybrid III-V on silicon laser device includes a layer structure, with a stack of III-V semiconductor gain materials, a silicon waveguide core and a cladding structure. The semiconductor gain materials stack is along a stacking direction, which is perpendicular to a main plane of the stack. The silicon waveguide core extends along a longitudinal direction, parallel to the main plane. The cladding structure extends between said waveguide core and the stack. The device further comprises an optical coupling structure formed in the layer structure. This coupling structure is designed: 1) to allow a hybrid-mode optical coupling of radiation between the stack of III-V semiconductor gain materials and the tapered waveguide core; and 2) to favor a coupling of a fundamental transverse optical mode of said radiation over a coupling of one or more higher-order transverse optical modes of said radiation from the stack into the waveguide core.

A vertical cavity surface emitting laser (VCSEL) may include an active region (e.g., one or more quantum wells) and a chirped pattern reflector. The active region may be configured to be electrically pumped such that the active region generates light having a fundamental mode and a higher order mode. The chirped pattern reflector may include a first portion presenting to the active region as a first portion of an effective mirror having a concave shape and a second portion presenting to the active region as a second portion of the effective mirror having a convex shape.

The present disclosure is generally directed to an EML with a filter layer disposed between an active region of the EML and a substrate of the EML to absorb a portion of unmodulated light energy, and preferably the unmodulated light energy caused by transverse electric (TE) substrate mode. The filter layer preferably comprises a material with an energy band gap (Eg) that is less than the energy band gap of the predetermined channel wavelength to absorb unmodulated laser light.