A multi-junction VCSEL is formed by as a compact structure that reduces lateral current spreading by reducing the spacing between adjacent active regions in the stack of such regions used to from the multi-junction device. At least two of the active regions within the stack are located adjacent peaks of the intensity profile of the VCSEL, with an intervening tunnel junction positioned at a trough between the two peaks. The alignment of the active regions with the peaks maximizes the generated optical power, while the alignment of the tunnel junction with the trough minimizes optical loss. The close spacing on adjacent peaks forms a compact structure (which may even include a cavity having a sub-λ optical length) that lessens the total path traveled by carriers and therefore reduces lateral current spread.

A multi-junction VCSEL is formed by as a compact structure that reduces lateral current spreading by reducing the spacing between adjacent active regions in the stack of such regions used to from the multi-junction device. At least two of the active regions within the stack are located adjacent peaks of the intensity profile of the VCSEL, with an intervening tunnel junction positioned at a trough between the two peaks. The alignment of the active regions with the peaks maximizes the generated optical power, while the alignment of the tunnel junction with the trough minimizes optical loss. The close spacing on adjacent peaks forms a compact structure (which may even include a cavity having a sub-λ optical length) that lessens the total path traveled by carriers and therefore reduces lateral current spread.

A VCSEL device having non-coaxial-with-one-another apertures and/or rotationally asymmetric apertures formed in layer(s) of the VCSEL structure to define more than one spatial mode in a light output in operation of the device. An array of such VCSEL devices configured to have different spatial modes at the output of different constituent VCSEL devices. Spatial asymmetry of structure of the constituent VCSEL devices and, therefore, arrays of VCSEL devices causes the overall light output to form an irregular grid of output spots of light. When the VCSEL array is equipped with an appropriate lens array, the spatial components of the light output of the VCSEL array are caused to overlap in the far at the imaging plane in a multiple spatial (and spectral) mode fashion, thereby reducing speckle in imaging applications.

An exemplary embodiment of the invention relates to a method of fabricating a radiation emitter (100) comprising the steps of fabricating a layer stack (10) that comprises a first reflector (12), an active region (13), an oxidizable layer (21-24), and a second reflector (14); and locally removing the layer stack (10), and thereby forming a mesa (M) of the radiation emitter (100), wherein said mesa (M) comprises the first reflector (12), the active region (13), the oxidizable layer (21-24) and the second reflector (14), wherein before or after locally removing the layer stack (10) and forming said mesa (M) the following steps are carried out: vertically etching blind holes (30) inside the layer stack (10), wherein the blind holes (30) vertically extend at least to the oxidizable layer (21-24) and expose the oxidizable layer (21-24); and oxidizing the oxidizable layer (21-24) via the sidewalls (31) of the blind holes (30) in lateral direction, wherein from each hole an oxidation front (32) radially moves outwards and wherein the etching is terminated before the entire oxidizable layer (21-24) is oxidized, thereby forming at least two unoxidized apertures, (40) each of which is limited by at least three oxidation fronts (32), inside the mesa.

A wafer may comprise a substrate layer and a plurality of vertical cavity surface emitting lasers (VCSELs) formed on or within the substrate layer. A respective trench-to-trench distance associated with the plurality of VCSELs may vary across the wafer based on a predicted variation of an oxidation rate of an oxidation layer across the wafer.

A semiconductor vertical resonant cavity light source includes an upper and lower mirror that define a vertical resonant cavity. An active region is within the cavity for light generation between the upper and lower mirror. At least one cavity spacer region is between the active region and the upper mirror or lower mirror. The cavity includes an inner mode confinement region and an outer current blocking region. An index guide in the inner mode confinement region is between the cavity spacer region and the upper or lower mirror. The index guide and outer current blocking region each include a lower and upper epitaxial material layer thereon with an epitaxial interface region in between. At least a top surface of the lower material layer includes aluminum in the interface region throughout a full area of an active part of the vertical light source.

This invention opens up the chip thickness for increasing VCSEL power. It describes a method by using multiple gain layers 10, separated by insulating layers 11, powered in parallel electrically through embedded electrodes 13, 14 connected through via holes. The gain layers, as a whole, are bounded on top and bottom by DBR mirrors 12. The structure, compared to a standard VCSEL, leads to higher power, lower resistive loss, higher device speed, higher beam quality, and fewer number of DBR layers.

A vertical-cavity surface-emitting laser (VCSEL) is provided that includes a mesa structure disposed on a substrate. The mesa structure defines an emission axis of the VCSEL. The mesa structure includes a first reflector, a second reflector, and a cascaded active region structure disposed between the first reflector and the second reflector. The cascaded active region structure includes a plurality of cascaded active region layers disposed along the emission axis, where each of the cascade active region layers includes an active region having multi-quantum well and/or dots layers (MQLs), a tunnel junction aligned with the emission axis, and an oxide confinement layer. The oxide confinement layer is disposed between the tunnel junction and MQLs, and has an electrical current aperture defined therein. The mesa structure defines an optical window through which the VCSEL is configured to emit light.

A VCSEL can include: an elliptical oxide aperture in an oxidized region that is located between an active region and an emission surface, the elliptical aperture having a short radius and a long radius with a radius ratio (short radius)/(long radius) being between 0.6 and 0.8, the VCSEL having a relative intensity noise (RIN) of less than −140 dB/Hz. The VCSEL can include an elliptical emission aperture having the same dimensions of the elliptical oxide aperture. The VCSEL can include an elliptical contact having an elliptical contact aperture therein, the elliptical contact being around the elliptical emission aperture. The elliptical contact can be C-shaped. The VCSEL can include one or more trenches lateral of the oxidized region, the one or more trenches forming an elliptical shape, wherein the oxidized region has an elliptical shape. The one or more trenches can be trapezoidal shaped trenches.

A method of manufacturing a surface emitting laser includes: preparing a substrate on which a lower reflector layer, an active layer and an upper reflector layer are formed in this order from the bottom, each of the lower reflector layer and the upper reflector layer including a semiconductor multilayer film; forming an insulating film on the upper reflector layer; cleaning the substrate using isopropyl alcohol after the forming; patterning a photoresist by applying the photoresist on the insulating film and exposing the photoresist, after the cleaning; and forming a high resistance region by implanting ions into portions of the lower reflector layer, the active layer and the upper reflector layer exposed from the photoresist, after the patterning; wherein the cleaning includes cleaning the substrate with a liquid of the isopropyl alcohol and drying the substrate in a vapor of the isopropyl alcohol.