Disclosed is an electrically pumped vertical cavity laser structure operating in the mid-infrared region, which has demonstrated room-temperature continuous wave operation. This structure uses an interband cascade gain region, two distributed mirrors, and a low-loss refractive index waveguide. A preferred embodiment includes at least one wafer bonded GaAs-based mirror.

A semiconductor laser comprising a single mode laser cavity having a stack of semiconducting layers defining a transversal p-n junction is provided. A plurality of electrodes are coupled to corresponding sections of the laser cavity along the longitudinal light propagation direction, each corresponding section defining one of an amplification section or a modulation section. One or more DC sources are coupled to the electrodes associated with the amplification sections to forward-bias the p-n junction above transparency, so as to provide gain in the associated amplification sections. One or more modulation signal sources are coupled to the electrodes associated with the modulation sections, and apply a modulation signal across the p-n junction below transparency, the modulation signal providing a modulation of an output optical frequency of the semiconductor laser. Each modulation section is operated in photovoltaic mode.

A quantum cascade laser or interband cascade laser for outputting a frequency comb. The laser's active waveguide comprises a combination of narrow and wide sections which are engineered in combination such that the laser is operable to produce lasing only in the fundamental mode across the operating wavelength range, the narrow section squeezing light propagating in the waveguide to output a frequency comb via four-wave mixing. The narrow and wide sections are further engineered to reduce the waveguide's net GVD, and also to reduce the GVD variation across the operating range compared to a comparable waveguide that is of constant width, thus producing a more stable frequency comb. The proportion of the laser's full dynamic range (i.e. from threshold to the rollover current where the maximum output power is achieved) over which lasing remains in the frequency comb regime is thereby increased compared with a constant width single mode waveguide.

A semiconductor laser includes an active region, a first distributed-Bragg-reflector region disposed contiguously with the active region, and a second distributed-Bragg-reflector region. The first distributed-Bragg-reflector region is formed contiguously with one side of the active region in a waveguide direction and includes a first diffraction grating. The second distributed-Bragg-reflector region is formed contiguously with to the other side of the active region in the waveguide direction and includes a second diffraction grating. The first diffraction grating includes recessed portions formed through a diffraction grating layer formed in the first distributed-Bragg-reflector region and convex portions adjacent to the recessed portions. The diffraction grating layer is made of a dielectric material.

Embodiments of the present disclosure are directed to a semiconductor optical amplifier including a semiconductor-based gain medium configured to receive a drive current and a variable-width waveguide coupled to the in the semiconductor-based gain medium, the variable-width waveguide including a plurality of narrow width regions and a plurality of wide width regions positioned alternately along a longitudinal axis of the waveguide. The variable-width waveguide further includes a plurality of transition regions having an adiabatically varying widths. Each transition region connects adjacent ones of the plurality of narrow width and width regions and the waveguide has a reduced drive current density in the plurality of wide width regions relative to the drive current density in the plurality of narrow width regions.

A light emitting device includes a substrate, a buffer layer, a first active layer, and a plurality of mesa regions. A portion of the first active layer includes a first electrical polarity. The plurality of mesa regions includes at least a portion of the first active layer, a light emitting region on the portion of the first active layer, and a second active layer on the light emitting region. A portion of the second active layer includes a second electrical polarity. The light emitting region is configured to emit light which has a target wavelength between 200 nm to 300 nm. A thickness of the light emitting region is a multiple of the target wavelength, and a dimension of the light emitting region parallel to the substrate is smaller than 10 times the target wavelength, such that the emitted light is confined to fewer than 10 transverse modes.

A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.

A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.

A broad area quantum cascade laser includes an optical cavity disposed between two sidewalls, the optical cavity including an active region for producing photons when a current is applied thereto, where the optical cavity is subject to a presence of at least one high order transverse optical mode due to its broad area geometry. The broad area quantum cascade laser may also include an optically lossy material disposed on at least a first portion of one or more of the two sidewalls.

A method for making a laser diode with a distributed grating reflector (RT) in a planar section of a semiconductor laser with stabilized wavelength includes providing a diode formed by a substrate (S), a first cladding layer (CL1) arranged on the substrate (S), an active layer (A) arranged on the first cladding layer (CL1) and adapted to emit a radiation, and a second cladding layer (CL2) arranged on the active layer (A), said cladding layers (CL1, CL2) being adapted to form a heterojunction to allow for efficient injection of current into the active layer (A) and optical confinement, and a contact layer. The manufacturing method provides for creating, on a first portion (ZA) of the device, a waveguide (GO) for confinement of the optical radiation and, on the remaining portion (ZP) of the device, two different gratings for light reflection and confinement. The two gratings define two different zones (R1, R2), wherein the first zone (R1) includes a grating of low order and high duty cycle, and is intended for reflection, and the second zone (R2) includes a grating of the same order, or a grating of a higher order than the previous one, and low duty cycle, and is mainly intended for light confinement. The waveguide (GO) for confining the optical radiation is implemented through a lithography and a subsequent etching, whereas the grating (RT) requires a high-resolution lithography and a shallow etching starting from a planar zone.