A light-emitting device includes an optical amplifier and gives off output light from optical amplifier by making a plurality of seed light rays, having mutually different wavelengths, incident on optical amplifier. Optical amplifier includes a medium portion containing a wavelength-converting element. Optical amplifier has wavelength-converting element thereof excited by excitation light to produce a plurality of partially coherent light rays, of which wavelengths are respectively the same as the mutually different wavelengths of plurality of seed light rays, thereby giving off, as output light, a multi-wavelength light beam. Excitation light has a shorter wavelength than any of plurality of seed light rays and is incident on the medium portion. Multi-wavelength light beam includes a plurality of light rays amplified. Plurality of light rays amplified have wavelengths, which are respectively the same as mutually different wavelengths of plurality of seed light rays.

A LiDAR system including a laser amplification system is disclosed. The laser amplification system includes a laser source and an optical amplifier. The laser source has a laser cavity and is configured to output electromagnetic radiation. The optical amplifier includes quantum dots and is positioned outside the laser cavity to receive the electromagnetic radiation output from the laser source. The optical amplifier amplifies the received electromagnetic radiation using the quantum dots and outputs the amplified electromagnetic radiation.

A wavelength tunable laser device includes: a first mirror; a second mirror; an optical amplifier provided between the first mirror and the second mirror; a wavelength tunable filter provided between the first mirror and the second mirror; and an optical waveguide coupling the optical amplifier and the wavelength tunable filter. The optical waveguide includes a first waveguide formed with a first width and a second waveguide formed with a second width wider than the first width.

A semiconductor laser includes a horizontal laser element including a first semiconductor layer arrangement having a first active zone for generating radiation. The horizontal laser element furthermore includes a first optical resonator extending in a direction parallel to a first main surface of the first semiconductor layer arrangement. Lateral boundaries of the first semiconductor layer arrangement run obliquely, such that electromagnetic radiation generated is reflectable in a direction of the first main surface of the first semiconductor layer arrangement. The semiconductor laser furthermore includes a vertical laser element having a second optical resonator extending in a direction perpendicular to the first main surface of the first semiconductor layer arrangement. The vertical laser element is arranged above the first semiconductor layer arrangement on the side of the first main surface in a beam path of electromagnetic radiation reflected at one of the lateral boundaries of the first semiconductor layer arrangement (112).

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.

An embodiment semiconductor optical device includes an optical waveguide including a core, and an active layer extending in the waveguide direction of the optical waveguide for a predetermined distance and arranged in a state in which the active layer can be optically coupled to the core. The core and the active layer are arranged in contact with each other. The core is formed of a material with a refractive index of about 1.5 to 2.2, such as SiN, for example. In addition, the core is formed to a thickness at which a higher-order mode appears. The higher-order mode is an E.sub.12 mode, for example.

Examples disclosed herein relate to quantum-dot (QD) photonics. In accordance with some of the examples disclosed herein, a QD semiconductor optical amplifier (SOA) may include a silicon substrate and a QD layer above the silicon substrate. The QD layer may include an active gain region to amplify a lasing mode received from an optical signal generator. The QD layer may have a gain recovery time such that the active gain region amplifies the received lasing mode without pattern effects. A waveguide may be included in an upper silicon layer of the silicon substrate. The waveguide may include a mode converter to facilitate optical coupling of the received lasing mode between the QD layer and the waveguide.

A semiconductor laser element is a semiconductor laser element that emits laser light, and the semiconductor laser element includes a substrate, a first semiconductor layer above the substrate, a light emitting layer above the first semiconductor layer, a second semiconductor layer above the light emitting layer, and a dielectric layer above the second semiconductor layer. The second semiconductor layer includes a waveguide that guides the laser light. A width of at least a portion of the waveguide is modulated with respect to a position in a direction of resonator length, the direction being a longitudinal direction of the waveguide. The waveguide includes a first waveguide and a second waveguide that is wider than the first waveguide. A difference between an effective index of refraction inside the waveguide and an effective index of refraction outside the waveguide is greater in the second waveguide than in the first waveguide.

In an optical device, a first semiconductor layer and a second semiconductor layer are formed to be thinner than a core, an active layer has a shape with an end in a waveguide direction tapers toward a tip end, the first semiconductor layer having a trapezoidal shape with a width thereof decreases toward a side of a third semiconductor layer from a side of the core in a plan view and a width thereof decreases as one end in the waveguide direction recedes from a central portion of the active region, and the second semiconductor layer having a trapezoidal shape with a width thereof decreases toward a side of a fourth semiconductor layer from the side of the core in a plan view and a width thereof decreases as one end in the waveguide direction recedes from the central portion of the active region.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.