Methods for fabricating vertical cavity surface emitting lasers (VCSELs) on a large wafer are provided. An un-patterned epi layer form is bonded onto a first reflector form. The first reflector form includes a first reflector layer and a wafer of a first substrate type. The un-patterned epi layer form includes a plurality of un-patterned layers on a wafer of a second substrate type. The first and second substrate types have different thermal expansion coefficients. A resulting bonded blank is substantially non-varying in a plane that is normal to an intended emission direction of the VCSEL. A first regrowth is performed to form first regrowth layers, some of which are patterned to form a tunnel junction pattern. A second regrowth is performed to form second regrowth layers. A second reflector form is bonded onto the second regrowth layers, wherein the second reflector form includes a second reflector layer.

A QCL may include a substrate, and a sequence of semiconductor epitaxial layers adjacent the substrate and defining an active region, an injector region adjacent the active region, and a waveguide optically coupled to the active region. The active region may include stages, each stage having an upper laser level and a lower laser level defining respective first and second wave functions. The upper laser level may have an upper laser level average coordinate, and the lower laser level may have a lower laser level average coordinate. The upper laser level average coordinate and the lower laser level average coordinate may have spacing of less than 10 nm. Wave functions for all active region energy levels located below the lower laser level may have greater than 10% overlap with the injector region.

A QCL may include a substrate, and a sequence of semiconductor epitaxial layers adjacent the substrate and defining an active region, an injector region adjacent the active region, and a waveguide optically coupled to the active region. The active region may include stages, each stage having an upper laser level and a lower laser level defining respective first and second wave functions. The upper laser level may have an upper laser level average coordinate, and the lower laser level may have a lower laser level average coordinate. The upper laser level average coordinate and the lower laser level average coordinate may have spacing of less than 10 nm. Wave functions for all active region energy levels located below the lower laser level may have greater than 10% overlap with the injector region.

A semiconductor laser is provided that includes a semiconductor layer sequence and electrical contact surfaces. The semiconductor layer sequence includes a waveguide with an active zone. Furthermore, the semiconductor layer sequence includes a first and a second cladding layer, between which the waveguide is located. At least one oblique facet is formed on the semiconductor layer sequence, which has an angle of 45° to a resonator axis with a tolerance of at most 10°. This facet forms a reflection surface towards the first cladding layer for laser radiation generated during operation. A maximum thickness of the first cladding layer is between 0.5 M/n and 10 M/n at least in a radiation passage region, wherein n is the average refractive index of the first cladding layer and M is the vacuum wavelength of maximum intensity of the laser radiation.

A semiconductor laser is provided that includes a semiconductor layer sequence and electrical contact surfaces. The semiconductor layer sequence includes a waveguide with an active zone. Furthermore, the semiconductor layer sequence includes a first and a second cladding layer, between which the waveguide is located. At least one oblique facet is formed on the semiconductor layer sequence, which has an angle of 45° to a resonator axis with a tolerance of at most 10°. This facet forms a reflection surface towards the first cladding layer for laser radiation generated during operation. A maximum thickness of the first cladding layer is between 0.5 M/n and 10 M/n at least in a radiation passage region, wherein n is the average refractive index of the first cladding layer and M is the vacuum wavelength of maximum intensity of the laser radiation.

A laser diode, comprising a transverse waveguide that is orthogonal to the lateral waveguide comprising an active layer between an n-type waveguide layer and a p-type waveguide layer, wherein the transverse waveguide is bounded by an n-type cladding layer on an n-side and p-type cladding layer on a p-side and a lateral waveguide bounded in a longitudinal direction at a first end by a high reflector (HR) coated facet and at a second end by a partial reflector (PR) coated facet, the lateral waveguide further comprising a buried higher order mode suppression layer (HOMSL) disposed beneath the p-cladding within the lateral waveguide or on one or both sides of the lateral waveguide or a combination thereof, wherein the HOMSL extends in a longitudinal direction from the HR facet a length less than the distance between the HR facet and the PR facet.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

A spectroscopic laser sensor based on hybrid III-V/IV system-on-a-chip technology. The laser sensor is configured to either (i) be used with a fiber-optic probe connected to an intravenous/intra-arterial optical catheter for direct invasive blood analyte concentration level measurement or (ii) be used to measure blood analyte concentration level non-invasively through an optical interface attached, e.g., to the skin or fingernail bed of a human. The sensor includes a III-V gain-chip, e.g., an AIGalnAsSb/GaSb based gain-chip, and a photonic integrated circuit, with laser wavelength filtering, laser wavelength tuning, laser wavelength monitoring, laser signal monitoring and signal output sections realized on a chip by combining IV-based semiconductor substrates and flip-chip AIGal-nAsSb/GaSb based photodetectors and embedded electronics for signal processing. Embodiments of the invention may be applied for real-time monitoring of critical blood analyte concentration levels such as lactates, urea, glucose, ammonia, albumin, etc.

There is provided a light-emitting device (1) including: a light-emitting element (20); a light-transmissive heat dissipation member (11) having a plate shape; a wavelength conversion member (12) that takes in, from a side of a light scattering layer (12a), light that is emitted from the light-emitting element (20) and passes through the light-transmissive heat dissipation member (11), and converts a wavelength in a fluorescent layer (12b); a lateral heat dissipation member that has a plate shape, includes a high-heat conduction member (13) in contact with a side surface of the wavelength conversion member (12) via a light reflection member (14), and is in contact with an upper surface of the light-transmissive heat dissipation member (11); and a package (21) that houses the light-emitting element (20) and supports a wavelength conversion unit (100) including the light-transmissive heat dissipation member (11), the wavelength conversion member (12), and the lateral heat dissipation member.

Several VCSEL devices for long wavelength applications in wavelength range of 1200-1600 nm are described. These devices include an active region between a semiconductor DBR on a GaAs wafer and a dielectric DBR regrown on the active region. The active region includes multi-quantum layers (MQLs) confined between the active n-InP and p-InAlAs layers and a tunnel junction layer above the MQLs. The semiconductor DBR is fused to the bottom of the active region by a wafer bonding process. The design simplifies integrating the reflectors and the active region stack by having only one wafer bonding followed by regrowth of the other layers including the dielectric DBR. An air gap is fabricated either in an n-InP layer of the active region or in an air gap spacer layer on top of the semiconductor DBR. The air gap enhances optical confinement of the VCSEL. The air gap may also contain a grating.