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.

A semiconductor laser including a waveguide having a core, a confinement layer to bury the core, and a metallization layer. The core includes an active core region. The confinement layer surrounds the core and includes a first confinement layer between the core and the semiconductor substrate below the core, a second confinement layer above the core, and a third confinement layer to either or both sides of the core. The metallization layer is located above the confinement layers and include a first metallization layer and a second metallization layer. The first metallization layer is in direct contact with the second confinement layer and the third confinement layer, while the second metallization layer is disposed above the first layer. The first metallization layer is tuned to have a plasmon resonance corresponding to a higher order mode with high loss.

A QCL may include a substrate, an emitting facet, and semiconductor layers adjacent the substrate and defining an active region. The active region may have a longitudinal axis canted at an oblique angle to the emitting facet of the substrate. The QCL may include an optical grating being adjacent the active region and configured to emit one of a CW laser output or a pulsed laser output through the emitting facet of substrate.

A quantum-cascade laser element includes: a semiconductor substrate; a semiconductor laminate formed on the semiconductor substrate to include a ridge portion configured to include an active layer having a quantum-cascade structure; an embedding layer including a first portion formed on a side surface of the ridge portion, and a second portion extending from an edge portion of the first portion on a side of the semiconductor substrate along a width direction of the semiconductor substrate; a metal layer formed on a top surface of the ridge portion, on the first portion, and on the second portion; and a dielectric layer disposed between the second portion and the metal layer. The dielectric layer is formed such that a part of the second portion is exposed from the dielectric layer. The metal layer is in contact with the second portion at the part.

In order to provide a QCL element operating in the near-infrared wavelength range, the present disclosure provides a quantum cascade laser element 1000 having a semiconductor superlattice structure (QCL structure 100) sandwiched between a pair of conductive sections 20 and 30. The semiconductor superlattice structure serves as an active region that emits electromagnetic waves. The active region has a plurality of unit structures 10U that are stacked on top of each other. Each unit structure includes four well layers 10W1-10W4 of a composition of Al.sub.xGa.sub.1−xN, separated from each other by barrier layers 10B1-10B5 of a composition of Al.sub.yGa.sub.1−yN with 0≤x<y≤1. Both of the conductive sections in the pair of conductive sections have a refractive index lower than that of the active region in which doped TCO inserted as a key role.

A quantum cascade laser includes a first and a second mesa waveguides disposed on a substrate, a first electrode, a second electrode, and a current blocking region disposed burying the first and second mesa waveguides. The first and second mesa waveguides extend in a first direction. The first and second mesa waveguides are arranged apart from each other by a distance in a second direction intersecting with the first direction. The current blocking region has a first portion disposed between the first and second mesa waveguides and a second portion disposed on the first portion. The end of the first electrode and the end of the second electrode are facing each other in the second direction. The second portion protrudes from a reference plane which includes a surface of the end of the first electrode and extends in the first and second directions.

An analysis device includes a substrate including a first surface, and a second surface positioned at a side opposite to the first surface; a light source part located at the first surface of the substrate, the light source part including a quantum cascade laser; a light detector located at the first surface of the substrate; and a wiring part located at the first surface of the substrate, the wiring part being electrically connected with the light source part and the light detector.

Provided is a surface emitting quantum cascade laser, including: semiconductor layers other than a laser active layer and the laser active layer; and a square-lattice or rectangular-lattice photonic crystal on the laser active layer, wherein a unit lattice of the square-lattice or rectangular-lattice photonic crystal is made of a composition A, and a composition B having a refractive index different from a refractive index of the composition A, and wherein the composition A is a compound semiconductor composition or metal composition, the composition B is a compound semiconductor composition, and the unit lattice of the square-lattice or rectangular-lattice photonic crystal has the following structure: a columnar structure body having a pentagonal bottom face and being made of the composition B is provided in a central part of the columnar structure body having the square or rectangular bottom face and being made of the composition A.

A system and method for tuning and infrared source laser in the Mid-IR wavelength range. The system and method comprising, at least, a plurality of individually tunable emitters, each emitter emitting a beam having a unique wavelength, a grating, a mirror positioned after the grating to receive at least one refracted order of light of at least one beam and to redirect the beam back towards the grating, and a micro-electro-mechanical systems device containing a plurality of adjustable micro-mirrors.