A light-emitting device includes a light emission section (Em), a separation groove (152), and a high reflectance region (Hr). The light emission section (Em) includes a stack structure (100) including an active layer (100), a first reflector (110), and a second reflector (120). The active layer (130) performs light emission by current injection. The first reflector (110) and the second reflector (120) are stacked in a first direction with the active layer (130) interposed therebetween. The separation groove (152) is provided symmetrically around the light emission section (Em) on an emission surface of light from the stack structure (100) in the first direction. The separation groove (152) is dug in the stack structure (100) in the first direction. The high resistance region (Hr) is provided in the stack structure (100) on the outer side of an outermost shape of the separation groove (152) on the emission surface. The high resistance region (Hr) has electrical resistance higher than that of the light emission section (Em).

An emitter may include a substrate, a conductive layer on at least a bottom surface of a trench, and a first metal layer to provide a first electrical contact of the emitter on an epitaxial side of the substrate. The first metal layer may be within the trench such that the first metal layer contacts the conductive layer within the trench. The emitter may further include a second metal layer to provide a second electrical contact of the emitter on the epitaxial side of the substrate, and an isolation implant to block lateral current flow between the first electrical contact and the second electrical contact.

A VCSEL may include an n-type substrate layer and an n-type bottom mirror on a surface of the n-type substrate layer. The VCSEL may include an active region on the n-type bottom mirror and a p-type layer on the active region. The VCSEL may include an oxidation layer over the active region to provide optical and electrical confinement of the VCSEL. The VCSEL may include a tunnel junction over the p-type layer to reverse a carrier type of an n-type top mirror. Either the oxidation layer is on or in the p-type layer and the tunnel junction is on the oxidation layer, or the tunnel junction is on the p-type layer and the oxidation layer is on the tunnel junction. The VCSEL may include the n-type top mirror over the tunnel junction, a top contact layer over the n-type top mirror, and a top metal on the top contact layer.

The present application relates to the technical field of semiconductor optoelectronics, in particular to a multi-active-region cascaded semiconductor laser. The multi-active-region cascaded semiconductor laser comprises: a plurality of cascaded active regions, wherein each cascaded active region comprises a plurality of active regions; and a tunnel junction, arranged on at least one side of the cascaded active region and electrically connected with the cascaded active region; wherein in the cascaded active region, at least one group of adjacent active regions are connected through a barrier layer. In this way, more active regions are added in the periodic gain structure, which improves the internal quantum efficiency of the device and also reduces the carrier density, thereby obtaining more gains. The barrier layer connection does not have the property of introducing a new pn junction, so the layer will not increase the turn-on voltage for device operation, and meanwhile the epitaxial growth is much simpler than that of the tunnel junction.

A method of incorporating a control structure within a VCSEL device cavity using a multiphase growth sequence includes forming a first mirror over a substrate, forming an active region over the first mirror, forming a spacer on a surface of the active region, forming a control structure on a surface of the spacer, and forming a second mirror over the control structure. The active region and the spacer are formed using a molecular beam epitaxy (MBE) process during an MBE phase of the multiphase growth sequence. The second mirror is formed using a metal-organic chemical vapor deposition (MOCVD) process during an MOCVD phase of the multiphase growth sequence. The control structure is formed using a chemical etching process during a transition period between the MBE phase and the MOCVD phase of the multiphase growth sequence.

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 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).

Provided is a vertical cavity surface emitting laser diode (VCSEL) with a small divergence angle. The VCSEL includes a multi-layer structure on a substrate. The multi-layer structure includes an active region and current confinement layers. Each of the current confinement layers has an optical aperture (OA). When the area of the OA of the current confinement layer outside the active region is larger than the areas of the OAs of the current confinement layers inside the active region, such that the VCSEL has a small divergence angle in the short pulse mode.

A columnar portion is formed by etching parts of an active layer and a first reflective layer. In this etching process, the columnar portion is formed by etching the first reflective layer to a position of a semiconductor layer. For example, it is etched to a thickness of approximately 3 μm.