A distributed feedback plus reflection (DFB+R) laser includes an active section, a passive section, a low reflection (LR) mirror, and an etalon. The active section includes a distributed feedback (DFB) grating and is configured to operate in a lasing mode. The passive section is coupled end to end with the active section. The LR mirror is formed on or in the passive section. The etalon includes a portion of the DFB grating, the passive section, and the LR mirror. The lasing mode of the active section is aligned to a long wavelength edge of a reflection peak of the etalon.

Some embodiments may include a semiconductor laser device comprising: an active layer to generate light; a front facet positioned at a first end of said active layer, with an AR coating or PR coating; a rear facet positioned on a second opposite end of said active layer thereby forming a resonator between said front facet and said rear facet; and a first order diffraction grating positioned within said resonator along only a portion of the length of said active layer, wherein the semiconductor laser device is arranged to emit light from both ends, and the diffraction grating has two non-contiguous segments each extending to one of the facets; or a single end, wherein the rear facet is a rear light reflecting facet with an HR-coating. Other embodiments may be disclosed and/or claimed.

A distributed feedback plus reflection (DFB+R) laser includes an active section, a passive section, a low reflection (LR) mirror, and an etalon. The active section includes a distributed feedback (DFB) grating and is configured to operate in a lasing mode. The passive section is coupled end to end with the active section. The LR mirror is formed on or in the passive section. The etalon includes a portion of the DFB grating, the passive section, and the LR mirror. The lasing mode of the active section is aligned to a long wavelength edge of a reflection peak of the etalon.

Disclosed herein is a spectroscopy device incorporating a mid-infrared laser. In one particular embodiment a spectroscopy device is provided including: a substrate; a single mode laser positioned on the substrate; a single mode detector positioned opposite to the single mode laser on the substrate. A gap is formed between the single mode laser and the single mode detector and a substance is positioned in the gap. The single mode laser is configured to output a tunable narrow wavelength of radiation towards the detector and when the single mode laser outputs a wavelength of radiation overlapping one of the substance's rotational-vibrational energy levels, the substance at least partially absorbs the radiation. The single mode detector is configured to measure the amount of narrow wavelength radiation that is not absorbed by the substance between the single mode detector and the single mode laser.

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.

Disclosed are embodiments of bidirectionally emitting semiconductor (BEST) laser architectures including higher order mode suppression structures. The higher order mode suppression structures are centrally located and extend from an inner transition boundary, which may be established by confronting high reflector (HR) facets in some embodiments or a central plane defining two sides of a unitary, bidirectional optical cavity in other embodiments. Examples of the higher order mode suppression structures include narrow regions of bidirectional flared laser oscillator waveguide (FLOW) devices, which are also referred to as reduced mode diode (REM) devices; high-index regions of bidirectional higher-order mode suppressed laser (HOMSL) devices; and non- or less-etched gain-guided lateral waveguides of bidirectional low divergence semiconductor laser (LODSL) devices. The aforementioned devices may also include scattering features, distributed feedback (DFB) gratings, distributed Bragg reflection (DBR) gratings, and combination thereof that also act as supplemental higher order mode suppression structures.

A quantum cascade laser includes a laser structure including a semiconductor stack and a semiconductor support, the laser structure having a first end face and a second end face opposite the first end face. The semiconductor stack is disposed on the semiconductor support. The laser structure includes a semiconductor mesa and a buried region, the semiconductor mesa including a core layer, and the buried region embedding the semiconductor mesa. The laser structure includes a first region, a second region, and a third region. The third region is provided between the first region and the second region. The first region includes the first end face. The semiconductor mesa includes a first stripe portion, a second stripe portion, and a first tapered portion, respectively, in the first region, the second region, and the third region. The first stripe portion and the second stripe portion have different mesa widths.

Provided is a semiconductor laser including: a core layer having an active layer and a diffraction grating layer optically coupled to the active layer; and paired clad layers arranged sandwiching the core layer, and formed with a waveguide along the core layer, and the semiconductor laser includes: a flat layer provided continuously with the diffraction grating layer along the waveguide; and a temperature control mechanism for controlling the temperature of the flat layer to a temperature different from that of the diffraction grating layer.

A semiconductor laser device includes a semiconductor substrate, a resonator unit formed on the semiconductor substrate and having an active layer, a diffraction grating formed on or underneath the active layer, a front facet of an inverted mesa slope, and a rear facet, an anti-reflection coating film formed on the front facet, a reflective film formed on the rear facet, an upper electrode formed on the resonator unit, and a lower electrode formed underneath the semiconductor substrate, wherein a length in a resonator direction of the resonator unit is shorter than a length in the resonator direction of the semiconductor substrate, and a laser beam is emitted from the front facet.

A Distributed Feedback Laser (DFB) mounted on a Silicon Photonic Integrated Circuit (Si PIC), the DFB having a longitudinal length which extends from a first end of the DFB laser to a second end of the DFB laser, the DFB laser comprising: an epi stack, the epi stack comprising: one or more active material layers; a layer comprising a partial grating, the partial grating extending from the second end of the DFB laser, only partially along the longitudinal length of the DFB laser such that it does not extend to the first end of the DFB laser; a highly reflective medium located at the first end of the DFB laser; and a back facet located at the second end of the DFB laser.