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.

Disclosed is an optically pumped vertical cavity laser structure operating in the mid-infrared region, which has demonstrated room-temperature continuous wave operation. This structure uses a periodic gain active region with type I quantum wells comprised of InGaAsSb, and barrier/cladding regions which provide strong hole confinement and substantial pump absorption. A preferred embodiment includes at least one wafer bonded GaAs-based mirror. Several preferred embodiments also include means for wavelength tuning of mid-IR VCLs as disclosed, including a MEMS-tuning element. This document also includes systems for optical spectroscopy using the VCL as disclosed, including systems for detection concentrations of industrial and environmentally important gases.

A light-emitting device includes: a light source including light-emitting elements configured to oscillate in a single transverse mode; and an optical member that is provided on a light-emitting path of the light source and configured to diffuse and emit light emitted by the light source.

Some embodiments relate to a vertical cavity surface emitting laser (VCSEL) device including a VCSEL structure overlying a substrate. The VCSEL structure includes a first reflector, a second reflector, and an optically active region disposed between the first and second reflectors. A first spacer laterally encloses the second reflector. The first spacer comprises a first plurality of protrusions disposed along a sidewall of the second reflector.

A surface emitting laser has a Vertical-Cavity Surface emitting laser (VCSEL) structure. The VCSEL structure includes an aperture provided by a current confinement structure. An optically discontinuous portion is formed in a top Distributed Bragg Reflector (DBR) of the VCSEL structure such that it is arranged in a region with a gap between it and the aperture.

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 vertical cavity surface emitting laser (VCSEL) device includes an oxide aperture layer positioned in close proximity to the active region of the device, typically within the cavity itself, as opposed to being positioned in the top DBR of the VCSEL. Reducing the spacing between the active region and the oxide aperture layer has been found to reduce the spread of current across the surface of the active region, allowing for a lower threshold current to be achieved. The closer positioning of the oxide aperture layer also reduced optical absorption and series resistance. The oxide aperture layer may be located at the first null in the standing wave pattern between the active region and the top DBR to minimize divergence of the beam and control the optical mode.

A light-emission device includes: a first light emitting element chip; a second light emitting element chip having a light output higher than a light output of the first light emitting element chip, the second light emitting element chip being configured to be driven independently from the first light emitting element chip and arranged side by side with the first light emitting element chip; and a light diffusion member including a first region provided on an emission path of the first light emitting element chip and a second region provided on an emission path of the second light emitting element chip, and having a diffusion angle at the second region larger than a diffusion angle at the first region.

A surface-emitting semiconductor laser includes: a substrate; a first electrode provided in contact with the substrate; a first light reflection layer provided over the substrate; a second light reflection layer provided over the substrate, with the first light reflection layer being interposed between the second light reflection layer and the substrate; an active layer provided between the second light reflection layer and the first light reflection layer; a current confining layer that is provided between the active layer and the second light reflection layer and includes a current injection region; a second electrode provided over the substrate, with the second light reflection layer being interposed between the second electrode and the substrate, at least a portion of the second electrode being provided at a position overlapping the current injection region; and a contact layer that is provided between the second electrode and the second light reflection layer and includes a contact region that is in contact with the second electrode, in which the contact region has a smaller area than an area of the current injection region.

A semiconductor heterostructure device includes a middle layer including an inner conducting channel and an outer current blocking region. A depleted heterojunction current blocking region (DHCBR) is within the outer current blocking region. The DHCBR includes a first depleting impurity specie including a Column II acceptor, and a second depleting impurity comprising oxygen which increases a depletion of the DHCBR so that the DHCBR forces current to flow into the conducting channel during electrical biasing under normal operation of the semiconductor heterostructure device.