A semiconductor laser device includes a first conductivity type cladding layer having a refractive index n.sub.c1, a first conductivity type side optical guide layer, an active layer, a second conductivity type side optical guide layer, and a second conductivity type cladding layer of n.sub.c2 laminated in order on a first conductivity type semiconductor substrate, wherein an oscillation wavelength is λ, a first conductivity type low refractive index layer of n.sub.1 lower than n.sub.c1 having a thickness of d.sub.1 is provided between the first conductivity type side optical guide layer and the first conductivity type cladding layer, a second conductivity type low refractive index layer of n.sub.2 lower than n.sub.c2 having a thickness of d.sub.2 is provided between the second conductivity type side optical guide layer and the second conductivity type cladding layer, and a condition of a normalization frequency v.sub.2>v.sub.1 is satisfied.

A reflectivity of an end surface protective film of a semiconductor laser element is made less than or equal to 1% in a wide wavelength range. Semiconductor laser element includes semiconductor stack body having front end surface and rear end surface, and end surface protective film disposed on front end surface of semiconductor stack body. End surface protective film includes first dielectric layer disposed on front end surface and second dielectric layer stacked outside first dielectric layer. Second dielectric layer includes first layer stacked on first dielectric layer, second layer stacked on first layer, and third layer stacked on second layer. For wavelength λ, of a laser beam, refractive index n2 of second layer is higher than refractive index n1 of first layer and refractive index n3 of third layer, and a film thickness of second layer ranges from λ(8n2) to 3λ(4n2) inclusive.

An optical semiconductor chip of the present disclosure includes a high frequency line between an electrode pad receiving a modulation signal and a modulation electrode on the optical waveguide constituting a laser. The depletion layer capacitance generated in an active layer of the optical waveguide is cancelled by an inductance component of the high frequency line. When a portion directly below the high frequency line is embedded with a low-dielectric-constant material or is made hollow, the parasitic capacitance is further reduced. The high frequency line may have a zigzag shape as well as a linear shape. The electrode pad on the optical semiconductor chip can be connected to other substrates including RF lines for modulation signal input by bumps or wire bonding.

The embodiment relates to a light-emitting device in which a positional relationship between a modified refractive index region's gravity-center position and the associated lattice point differs from a conventional device, and a production method. In this device, a stacked body including a light-emitting portion and a phase modulation layer optically coupled to the light-emitting portion is on a substrate. The phase modulation layer includes a base layer and plural modified refractive index regions in the base layer. Each modified refractive index region's gravity-center position locates on a virtual straight line passing through a corresponding reference lattice point among lattice points of a virtual square lattice on the base layer's design plane. A distance between the reference lattice point and the modified refractive index region's gravity center along the virtual straight line is individually set such that this device outputs light forming an optical image.

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 method for producing a semiconductor chip (100) is provided, in which, during a growth process for growing a first semiconductor layer (1), an inhomogeneous lateral temperature distribution is created along at least one direction of extent of the growing first semiconductor layer (1), such that a lateral variation of a material composition of the first semiconductor layer (1) is produced. A semiconductor chip (100) is additionally provided.

A semiconductor chip (100) is provided, having a first semiconductor layer (1), which has a lateral variation of a material composition along at least one direction of extent. Additionally provided is a method for producing a semiconductor chip (100).

A semiconductor laser in a ridge waveguide structure includes: a semiconductor substrate; a lower cladding layer which is formed on the semiconductor substrate; an active layer and a semiconductor layer which are in parallel on the lower cladding layer and are connected with each other; a first upper cladding layer locally aligned above the active layer; a second upper cladding layer locally aligned above the semiconductor layer; and a third upper cladding layer locally aligned above the active layer to confine light which is guided in the active layer, wherein the semiconductor layer has a band gap which is larger than that of the active layer. According to this constitution, an optical semiconductor device with high reliability in which the ridge waveguide structure whose manufacturing is relatively easy is applied, and current diffusion and electrical crosstalk between lasers in the ridge waveguide structure are suppressed is enabled.

A laser diode includes a substrate, an epitaxial structure, an electrode contacting layer and an optical cladding layer. The epitaxial structure is disposed on the substrate, and is formed with a ridge structure opposite to the substrate. The electrode contacting layer is disposed on a top surface of the ridge structure. The optical cladding layer has a refractive index smaller than that of the electrode contacting layer The optical cladding layer includes a first cladding portion which covers side walls of the ridge structure, and a second cladding portion which is disposed on a portion of the top surface of the ridge structure. A method for manufacturing the abovementioned laser diode is also disclosed.

A semiconductor laser diode and a method for manufacturing a semiconductor laser diode are disclosed. In an embodiment a semiconductor laser diode includes an epitaxially produced semiconductor layer sequence comprising at least one active layer and a gallium-containing passivation layer on at least one surface region of the semiconductor layer sequence.