Provided is a semiconductor laser diode including multiple active layers and a grating layer. The semiconductor laser diode includes two (or more than two) active layers, a grating layer, and a tunnel junction. The grating layer and the tunnel junction are provided between the two active layers. The tunnel junction is electrically connected to the two active layers, and the two active layers share and are optically coupled to the grating layer, thereby improving the external quantum efficiency and slope efficiency of the semiconductor laser diode.

An electroabsorption modulated laser having a first face, a second face, an optical cavity and an active region, the optical cavity being defined by a semiconductor substrate and having a length extending between the first face and the second face, and the active region being configured for injection of charge into the cavity and having effective bandgap energies at respective distances along the length of the cavity, the electroabsorption modulated laser comprising a first modulator section extending between a first position and a second position and comprising a first part of the active region, and a second modulator section extending between the second position and a third position and comprising a second part of the active region, wherein the bandgap energy of the first part of the active region adjacent the first position is higher than the bandgap energy adjacent the second position.

A vertical cavity surface emitting laser (VCSEL) device may include a substrate layer and a first set of epitaxial layers, for a first VCSEL, disposed on the substrate layer. The first set of epitaxial layers may include a first set of mirrors and at least one first active layer. The VCSEL device may include a second set of epitaxial layers, for a second VCSEL, disposed on the first set of epitaxial layers for the first VCSEL. The second set of epitaxial layers may include a second set of mirrors and at least one second active layer. The first VCSEL and the second VCSEL may be configured to emit light in a light emission direction. The at least one first active layer of the first VCSEL may be offset in the light emission direction from the at least one second active layer of the second VCSEL.

A beating spectroscopy device includes: first and second quantum cascade lasers; a quantum cascade detector; and a sample holder configured to hold a sample on an optical path between the second quantum cascade laser and the quantum cascade detector. Lights from the first and second quantum cascade lasers are detected by the quantum cascade detector while a wavelength of the light from the second quantum cascade laser is changed to scan a frequency of a beating signal having a frequency in accordance with a wavelength difference between the lights from the first and second quantum cascade lasers.

A novel, monolithically integrated mid-IR optical phased array (OPA) structure which eliminates the wafer bonding process to achieve highly efficient surface emitting optical beam steering in two dimensions is disclosed. Since solar energy is about 15-20 times smaller than that at 1.55 um, mid-IR is more favorable for the atmospheric transmission due to lower solar radiance backgrounds. For the beam steering, thermo-optic phase shifting is used for azimuthal plane beam steering and laser wavelength tuning is used for elevation plane beam steering. The OPA structure disclosed comprises a wavelength- tunable a QCL, a 1×32 splitter, thermo-optic phase-shifters, and sub-wavelength grating emitters. The disclosed OPA provides a low-cost, low-loss, low-power consumption, robust, small footprint, apparatus that may be used with expendable UAV swarms. A LiDAR may be created by monolithically integrating a QCD with the apparatus. Other embodiments are described and claimed.

In the present disclosure, in an EADFB laser in which an SOA has been integrated, a new configuration in which a problem of deterioration of optical waveform quality and insufficient optical output is solved or mitigated while taking advantage of characteristics that the same layer structure can be used and a manufacturing process can be simplified is shown. In an optical transmitter of the present disclosure, a waveguide structure having different core widths (waveguide widths) is adopted while using the same layer structure for a DFB laser and the SOA. Waveguides with different core widths are adopted so that a problem of insufficient saturated optical output or waveform deterioration due to a pattern effect is solved and mitigated. A passive waveguide region having a tapered shape is introduced in a part between an EA modulator and the SOA so that a waveguide width is continuously changed.

The present disclosure describes epitaxial oxide field effect transistors (FETs). In some embodiments, a FET comprises: a substrate comprising an oxide material; an epitaxial semiconductor layer on the substrate; a gate layer on the epitaxial semiconductor layer; and electrical contacts. In some cases, the epitaxial semiconductor layer can comprise a superlattice comprising a first and a second set of layers comprising oxide materials with a first and second bandgap. The gate layer can comprise an oxide material with a third bandgap, wherein the third bandgap is wider than the first bandgap. In some cases, the epitaxial semiconductor layer can comprise a second oxide material with a first bandgap, wherein the second oxide material comprises single crystal A.sub.xB.sub.1-xO.sub.n, wherein 0<x<1.0, wherein A is Al and/or Ga, wherein B is Mg, Ni, a rare earth, Er, Gd, Ir, Bi, or Li.

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.

The laser module includes a QCL element, a diffraction grating unit, a first lens holder, a second lens holder, and a mount member. The fourth mounting portion of the mount member is provided with a placement hole into which the protruding portion of the diffraction grating unit is inserted. The placement hole is longer than the protruding portion so that the protruding portion can be slid in the X-axis direction relative to the placement hole. A wall surface for positioning the diffraction grating unit is provided between the third mounting portion and the fourth mounting portion. The diffraction grating unit includes a positioning surface facing the wall surface. The diffraction grating unit is fixed to the fourth mounting portion in a state where the protruding portion is inserted into the placement hole and the positioning surface is in surface contact with the wall surface.

The laser module includes a QCL element, a diffraction grating unit, a first lens holder, a second lens holder, and a mount member. The first mounting portion has a first top surface on which the first lens holder is mounted via an adhesive layer. The third mounting portion has a third top surface on which the second lens holder is mounted via an adhesive layer. The second mounting portion has a second top surface located higher than the first top surface and the third top surface, a first side surface connecting the second top surface and the first top surface, and a second side surface connecting the second top surface and the third top surface. A notch extending from the second top surface to the first top surface or the third top surface is formed in at least one of the first side surface and the second side surface.