A vertical cavity surface-emitting laser configured to emit laser light having a wavelength of 830 nm to 910 nm includes a substrate having a main surface including GaAs, a first distributed Bragg reflector, an active layer, and a second distributed Bragg reflector. The substrate, the first distributed Bragg reflector, the active layer, and the second distributed Bragg reflector are arranged in a first axis direction intersecting the main surface. The main surface has an off angle of 6° or more with respect to a (100) plane. The active layer includes In.sub.xAl.sub.yGa.sub.1-x-yAs (0<x<1, 0≤y<1). The active layer has a strain. An absolute value of the strain is 0.5% to 1.4%.

A light-emitting device according to an embodiment of the present disclosure includes: a semiconductor stack in which a first light reflection layer configured by an arsenic-based semiconductor layer including carbon as an impurity, an active layer, and a second light reflection layer are stacked; a first buffer layer provided on the first light reflection layer side of the semiconductor stack, having one face that faces the semiconductor stack and another face that is on an opposite side of the one face, and configured by a phosphorus-based semiconductor layer; and a second buffer layer provided at least between the first light reflection layer and the first buffer layer, and configured by an arsenic-based semiconductor layer including zinc or magnesium as an impurity.

Self-mixing interferometry (SMI) sensors may include vertical cavity surface emitting lasers (VCSEL), photodetectors, and microelectromechanical systems (MEMS). The VCSEL, photodetectors, and MEMS may be vertically stacked. The MEMS may be moveable with respect to a VCSEL and may change a cavity length associated with the VCSEL. By changing the cavity length associated with the VCSEL, certain properties of emitted light may be changed, such as a wavelength value of the emitted light.

A light emitting element according to the present disclosure includes a first light reflecting layer 41, a laminated structure 20, and a second light reflecting layer 42 laminated to each other. The laminated structure 20 includes a first compound semiconductor layer 21, a light emitting layer 23, and a second compound semiconductor layer 22 laminated to each other from a side of the first light reflecting layer. Light from the laminated structure 20 is emitted to an outside via the first light reflecting layer 41 or the second light reflecting layer 42. The first light reflecting layer 41 has a structure in which at least two types of thin films 41A and 41B are alternately laminated to each other in plural numbers. A film thickness modulating layer 80 is provided between the laminated structure 20 and the first light reflecting layer 41.

A collinear T-cavity VECSEL system generating intracavity Hermite-Gaussian modes at multiple wavelengths, configured to vary each of these wavelengths individually and independently. A mode converter element and/or an astigmatic mode converter is/are aligned intracavity to reversibly convert the Gaussian modes to HG modes to Laguerre-Gaussian modes, the latter forming the system output having any of the wavelengths provided by the spectrum resulting from nonlinear frequency-mixing intracavity (including generation of UV, visible, mid-IR light). The laser system delivers Watt-level output power in tunable high-order transverse mode distribution.

A measurement method for a vertical cavity surface emitting laser diode (VCSEL) and an epitaxial wafer test fixture are provided, especially the Fabry-Perot Etalon of the bottom-emitting VCSEL can be measured. When the Fabry-Perot Etalon of the bottom-emitting VCSEL is measured by a measurement apparatus, a light of the test light source of the measurement apparatus is incident from the substrate surface of the VCSEL epitaxial wafer such that the Fabry-Perot Etalon of the bottom-emitting VCSEL is acquired. Through the VCSEL epitaxial wafer test fixture, the bottom-emitting VCSEL can be directly measured by the existing measurement apparatus such that there is no need to change the optical design of the measurement apparatus, and it can prevent the VCSEL epitaxial wafer from being scratched or contaminated.

A bottom-emitting multijunction VCSEL array includes a first reflector region, a multijunction active region, and a second reflector region. In one aspect, the multijunction VCSEL array is attached to a submount by flip-chip bonding. In another aspect, the multijunction VCSEL array further includes a contact layer formed between the first reflector region and the substrate. The multijunction VCSEL array is attached to a submount by flip-chip bonding.

A narrow linewidth mid infrared laser, including a pumping laser diode with a fast-axis compressor and a pumping wavelength λ.sub.o; and an optical resonator arranged to receive the pumping wavelength λ.sub.o, the optical resonator including a laser crystal with a lasing wavelength λ.sub.p, a dichroic mirror, and a nonlinear crystal to generate an idler wavelength λ.sub.i.

A layered structure includes a first layer being a single material and a cavity coupled to the first layer. The first layer includes a porous region to form a first distributed Bragg reflector (DBR). The porous region includes alternating first porous and second porous sublayers of the single material to form the first DBR. The cavity includes an active region to generate radiation, detect radiation, or both. Advantageously, the layered structure and method of forming the layered structure improves the speed of manufacturing DBRs, reduces strain in the layered structure, reduces the size of the layered structure, and increases throughput.

A reflecting mirror includes a first film and a second film on the first film, and has a reflection band where a center wavelength is λ. The first film includes a layer having a first average refractive index and another layer having a second average refractive index higher than the first average refractive index. The second film includes a layer having a third average refractive index and another layer having a fourth average refractive index higher than the third average refractive index. A sum of optical film thicknesses of the two layers of the first film is λ/2. A sum of optical film thicknesses of the two layers of the second film is greater than or equal to (n+1)λ/2 (n is an integer greater than or equal to 1).