A synthesized grating is provided comprising a substrate/layer, and a plurality of alternating aperiodic non-uniform low and high index profiles on a surface of the substrate/layer defining a transmission/reflection spectrum for one of either single or multi-frequency operation of said grating in an optical cavity. A method is also provided for designing the synthesized grating, comprising determining a grating structure of given profiles through analysis of an optimized weighted sum and mapping the grating profile to said surface with the plurality of alternating non-uniform low and high index profiles. A distributed feedback laser is also provided having top, bottom and two sides, comprising a top electrode, a cladding layer disposed below the top electrode a bottom electrode, a substrate disposed above the bottom electrode, one of either an active or passive waveguide layer, a synthesized aperiodic grating layer providing distributed minors, and wherein the waveguide layer and synthesized aperiodic grating layer are disposed between said the substrate and cladding layer and are separated by a spacer layer.

The laser module includes a QCL element, a MEMS diffraction grating, a first lens holder disposed on a side opposite to a side on which the MEMS diffraction grating is disposed with respect to the QCL element, a second lens holder disposed between the QCL element and the MEMS diffraction grating, a package, an electrode terminal disposed along an inner wall surface of the package, and a wire for electrically connecting the electrode terminal and the QCL element. An end portion of the wire on a side where the QCL element is disposed is disposed at a position between the first lens holder and the second lens holder when viewed from a direction orthogonal to a facing direction in which the first lens holder and the second lens holder face each other.

An optical device is provided that includes a waveguide layer and at least one grating structure. A coupling coefficient of the at least one grating structure to a fundamental optical mode supported by the waveguide layer is greater than a coupling coefficient of the at least one grating structure to at least one higher order transverse optical mode supported by the waveguide layer.

The present disclosure relates to a diode laser having reduced beam divergence. Some implementations reduce a beam divergence in the far field by means of a deliberate modulation of the real refractive index of the diode laser. An area of the diode laser (e.g., the injection zone), may be structured with different materials having different refractive indices. In some implementations, the modulation of the refractive index makes it possible to excite a supermode, the field of which has the same phase (in-phase mode) under the contacts. Light, which propagates under the areas of a lower refractive index, obtains a phase shift of π after passing through the index-guiding trenches. Consequently, the in-phase mode is supported and the formation of the out-of-phase mode is prevented. Consequently, the laser field can, in this way, be stabilized even at high powers such that only a central beam lobe remains in the far field.

A semiconductor laser, an optical transmitter component, an optical line terminal, and an optical network unit. The semiconductor laser includes a substrate, a lower waveguide layer, a lower confining layer, a central layer, an upper confining layer, a grating layer, an upper waveguide layer, and an electrode layer that are sequentially formed on the substrate. The upper confining layer, the central layer, and the lower confining layer in a filtering region form a core layer of the filtering region. The grating layer in the filtering region includes a slanted grating. Thus, a modulation chirp and dispersion of a transmitted optical pulse can be reduced.

A laser includes an active region surrounded by first and second waveguide layers. Two or more mask openings are formed within a dielectric layer on a surface parallel to the active region. A refractive grating is formed on the dielectric mask openings and includes three-dimensional grating features spaced apart in the light-propagation direction of the laser. The refractive grating provides modulation of a real part of the effective refractive index of the laser and modulation of the imaginary part is provided by modulation of the current flow through the mask openings.

It is provided a method for fabricating an electroabsorption modulated laser comprising generating a single mode laser section and an electroabsorption modulator section, comprising fabricating at least one n-doped layer of the laser section and at least one n-doped layer of the modulator section; generating an isolating section for electrically isolating at least the n-doped layer of the laser section and the n-doped layer of the modulator section from one another. Generating the isolating section comprises epitaxially growing at least one isolating layer and structuring the isolating layer before the generation of the n-doped layer of the laser section and the n-doped layer of the modulator section.

A monolithic integrated semiconductor random laser comprising substrate, lower confinement layer on the substrate, active layer on the lower confinement layer, upper confinement layer on the active layer, strip-shaped waveguide layer longitudinally made in middle of the upper confinement layer, P.sup.+ electrode layer divided into two segments and made on the waveguide layer and N.sup.+ electrode layer on a back face of the lower confinement layer, wherein the two segments correspond respectively to gain region and random feedback region. The random feedback region uses a doped waveguide to randomly feedback light emitted by the gain region and then generates random laser which is random in frequency and intensity. Further, the semiconductor laser is light, small, stable in performance and strong in integration.

To provide a two-dimensional photonic crystal surface emitting laser capable of improving characteristics of light to be emitted, in particular, optical output power. The two-dimensional photonic crystal surface emitting laser includes: a two-dimensional photonic crystal including a plate-shaped base member and modified refractive index regions where the modified refractive index regions have a refractive index different from that of the plate-shaped base member and are two-dimensionally and periodically arranged in the base member; an active layer provided on one side of the two-dimensional photonic crystal; and a first electrode and a second electrode provided sandwiching the two-dimensional photonic crystal and the active layer for supplying current to the active layer, where the second electrode covers a region equal to or wider than the first electrode.

An optical semiconductor element includes, in order, a semiconductor laser, an optical waveguide, a loop waveguide, and a ring resonator optically coupled to the loop waveguide, in which a distance between the semiconductor laser and the ring resonator is 1 m or more and 200 m or less.