The present invention discloses a tunable semiconductor laser based on half-wave coupled partial reflectors. The laser comprises two resonant cavities; one resonant cavity is mainly composed of an optical waveguide, a first partial reflector and a second partial reflector, and the other resonant cavity is mainly composed of an optical waveguide, a first partial reflector and a second partial reflector. The resonant cavities are arranged along the same straight line and coupled to each other, and the two second partial reflectors in the two resonant cavities are connected by a common coupling waveguide. The present invention has the best single-mode selection, and an emitted wavelength can be switched between a series of channels; an optical grating needs not to be manufactured, and the structure is simple; and the laser has a high degree of freedom in coupler design and a great manufacturing tolerance and can realize large-scale digital tuning.

A light source device includes: a plurality of laser light sources, each configured to emit a light beam; a plurality of collimating lenses, each configured to collimate the light beam emitted from a corresponding one of the laser light sources; a first transmission diffraction grating configured to diffract and combine, in an identical diffraction angle direction, the light beams transmitted through the collimating lenses and incident on a single region at different incident angles; a sensor configured to detect a positional deviation in diffracted light beams that are diffracted and combined by the first transmission diffraction grating; and a plurality of wavelength selecting elements, each disposed on an optical path between a respective one of the collimating lenses and the first transmission diffraction grating and configured to select a wavelength of a corresponding one of the light beams incident on the first transmission diffraction grating.

Provided are a laser device and a method of transforming laser spectrum, which provide a laser frequency stabilization and significant narrowing a laser spectrum. A laser device includes at least one multiple longitudinal mode laser (L) for generating a laser light having a spectrum of multiple longitudinal modes; at least one high quality factor (high-Q) microresonator (M) optically feedback coupled to the at least one multiple longitudinal mode laser (L); and a tuner (TU) for tuning the spectrum of multiple longitudinal modes of the laser light. The laser device is configured to output an output laser light having an output spectrum with at least one dominant longitudinal laser mode each at a reduced linewidth of the dominant longitudinal laser mode. The laser device allows increasing an emission power of a narrow linewidth lasing without an additional amplification while keeping a compact size of a device with a limited number of optical elements.

There is disclosed a DBR laser and a method of use. The DBR laser comprises a phase section in a cavity of the DBR laser and configured to adjust an optical path length of the cavity. A DBR section comprises a frequency tuning system configured to adjust a Bragg frequency of the DBR section. A detector is configured to detect laser light transmitted through the DBR section. A controller is configured: to cause the phase section to apply a dither to the optical path length of the cavity or cause the frequency tuning system to apply a dither to the Bragg frequency of the DBR section; to use the detector to monitor intensity of light transmitted from the laser cavity via the DBR section during application of the dither; to determine a deviation from longitudinal mode centre operation on the basis of the monitored intensity; and to cause the frequency tuning system to adjust the Bragg frequency of the DBR section in order to reduce said deviation, or cause the phase section to adjust the optical path length of the cavity in order to reduce said deviation.

A light source device includes: a plurality of laser light sources, each configured to emit a light beam; a plurality of collimating lenses, each configured to collimate the light beam emitted from a corresponding one of the laser light sources; a first transmission diffraction grating configured to diffract and combine, in an identical diffraction angle direction, the light beams transmitted through the collimating lenses and incident on a single region at different incident angles; a sensor configured to detect a positional deviation in diffracted light beams that are diffracted and combined by the first transmission diffraction grating; and a plurality of wavelength selecting elements, each disposed on an optical path between a respective one of the collimating lenses and the first transmission diffraction grating and configured to select a wavelength of a corresponding one of the light beams incident on the first transmission diffraction grating.

A monolithic integrated semiconductor random laser composed of a gain region and random feedback region, comprising: a substrate, a lower confinement layer on the substrate, an active layer on the lower confinement layer, an upper confinement layer on the active layer, a strip-shaped waveguide layer longitudinally made in middle of the upper confinement layer, a P.sup.+ electrode layer divided into two segments by an isolation groove and made on the waveguide layer, and an N.sup.+ electrode layer on a back face of the lower confinement layer. The two segments of the P.sup.+ electrode layer correspond respectively to the gain region and the random feedback region. The random feedback region uses a doped waveguide to randomly feed back light emitted and amplified by the gain region. As a result, random laser is emitted. Frequency and intensity of laser emitted by semiconductor laser are random, and a monolithic integration structure is used, making semiconductor laser be light, small, stable in performance, and strong in integration.

A monolithic laser device assembly 10A in the present disclosure includes a first gain portion 20 having a first end portion 20A and a second end portion 20B, a second gain portion 30 having a third end portion 30A and a fourth end portion 30B, one or multiple ring resonators 40, a semiconductor optical amplifier 50 for amplifying a laser light emitted from the first gain portion 20, and a pulse selector 60 disposed between the first gain portion 20 and the semiconductor optical amplifier 50, in which the ring resonator 40 is optically coupled with the first gain portion 20 and with the second gain portion 30, and laser oscillation is performed on either the first gain portion 20 or the second gain portion 30.

A light emitter device (100) comprises a substrate (10) and a photonic crystal (20), which is arranged on the substrate (10) and comprises pillar- and/or wall-shaped semiconductor elements (21), which are arranged periodically standing out from the substrate (10), wherein the photonic crystal (20) forms a resonator, in which the semiconductor elements (21) are arranged in a first resonator section (22) with a first period (d.sub.1), in a second resonator section (23) with a second period (d.sub.2) and in a third resonator section (24) with a third period (d.sub.3), wherein on the substrate (10) the second resonator section (23) and the third resonator section (24) are arranged on two mutually opposing sides of the first resonator section (22) and the second period (d.sub.2) and the third period (d.sub.3) differ from the first period (d1), the first resonator section (22) forms a light-emitting medium and the third resonator section (24) forms a coupling-out region, through which a part of the light field in the first resonator section (22) can be coupled out of the resonator in a light outcoupling direction parallel to a substrate surface (11) of the substrate (10). Methods for operating and producing the light emitter device (100) are also described.

the laser arrangement (1) is configured such that the electrical connection (14) provides a direct current connection between the driver (13) and the laser (11) such that a photocurrent (I.sub.photo) that is generated in the electrode-absorption modulator section (112) of the laser (11) by illumination with light of the laser section (111) at least partially flows to the driver (13) and at least contributes to the energy supply of the driver (13).

An external resonance type laser module includes a quantum cascade laser, a MEMS diffraction grating configured to include a diffraction/reflection portion configured to diffract and reflect light emitted from the quantum cascade laser and return a part of the light to the quantum cascade laser by swinging the diffraction/reflection portion, and a controller configured to control driving of the quantum cascade laser. The controller is configured to pulse-drive the quantum cascade laser such that pulsed light of a second frequency higher than a first frequency at which the diffraction/reflection portion swings is emitted from the quantum cascade laser and a phase of the pulsed light changes each time the diffraction/reflection portion reciprocates m times (m: an integer of 1 or more).