An optical semiconductor device outputting a predetermined wavelength of laser light includes a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction. The optical semiconductor device includes a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer. The optical semiconductor device further includes an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer. The quantum well active layer is doped with 0.3 to 1×10.sup.18/cm.sup.3 of n-type impurity.

A monolithic edge emitting semiconductor laser comprising multiple laser diodes using aluminum indium gallium arsenide phosphide AlInGaAs/InGaAsP/InP material system, emitting in long wavelengths (1250 nm to 1720 nm). Each laser diode contains an active region comprising aluminium indium gallium arsenide quantum wells (AlInGaAs QW) and aluminum indium gallium arsenide (AlInGaAs) barriers and is connected to the subsequent monolithic laser diode by highly doped, low bandgap and low resistive indium gallium arsenide junction called tunnel junction.

A semiconductor optical device includes a substrate of a first conductivity type; an optical confinement layer of the first conductivity type, which is arranged above the substrate of the first conductivity type; a multi quantum well layer, which is arranged above the optical confinement layer of the first conductivity type, and comprises a plurality of well layers and a plurality of barrier layers; an optical confinement layer of a second conductivity type, which is arranged on the multi quantum well layer; and a PL stabilization layer, which is arranged between the substrate of the first conductivity type and the multi quantum well layer. The PL stabilization layer having a thickness that is half a thickness of the multi quantum well layer or more, and having a composition wavelength that is shorter than a composition wavelength of the plurality of well layers of the multi quantum well layer.

A semiconductor optical device includes an SOI substrate having a waveguide of silicon, and at least one gain region of a group III-V compound semiconductor having an optical gain bonded to the SOI substrate. The waveguide has a bent portion and multiple linear portions extending linearly and connected to each other through the bent portion. The gain region is disposed on each of the multiple linear portions.

The present disclosure is generally directed to an EML with a filter layer disposed between an active region of the EML and a substrate of the EML to absorb a portion of unmodulated light energy, and preferably the unmodulated light energy caused by transverse electric (TE) substrate mode. The filter layer preferably comprises a material with an energy band gap (Eg) that is less than the energy band gap of the predetermined channel wavelength to absorb unmodulated laser light.

It is an aim of the present invention to provide ultra-compact highly-integrated diffraction-grating semiconductor lasers on chips. Various embodiments combined enable the lasers to be compact in size, light weight, mechanically rugged, low in manufacturing cost, and in some cases high in electrical wall-plugged power efficiency or high in optical power output, comparing to typical lasers based on discrete optical components.

An optical waveguide structure includes a lower cladding layer positioned on a substrate; an optical guide layer positioned on the lower cladding layer; an upper cladding layer positioned on the optical guide layer; and a heater positioned on the upper cladding layer. The lower cladding layer, the optical guide layer, and the upper cladding layer constitute a mesa structure. The optical guide layer has a lower thermal conductivity than the upper cladding layer. An equation “W.sub.wg≤W.sub.mesa≤3×W.sub.wg” is satisfied, wherein W.sub.mesa represents a mesa width of the mesa structure, and W.sub.wg represents a width of the optical guide layer. The optical guide layer occupies one-third or more of the mesa width in a width direction of the mesa structure.

An optical semiconductor device outputting a predetermined wavelength of laser light includes a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction. The optical semiconductor device includes a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer. The optical semiconductor device further includes an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer. The optical semiconductor device is applied to a ridge-stripe type laser.

A semiconductor optical device (40, 50, 60) comprises a first region 42 comprising an active region configured such that electrons and holes recombine in the active region to produce photons when a voltage is applied to the device. The device comprises at least one second region (43, 44, 53, 54, 62, 63) comprising a quantum well structure which is configured to trap electrons only, to trap holes only, or to trap different amounts of electrons and holes. The second region is arranged at a distance from the first region which is sufficiently close to the first region such that a charge imbalance develops in the first region when a voltage is applied to the device, thereby to reduce Auger recombination in the first region.

An optical device includes a first reflector; a second reflector; an elastic support unit supporting the second reflector; a piezoelectric element on the elastic support unit; a light emitter configured to emit light having an oscillation wavelength; and circuitry configured to output a signal to apply drive voltage to the piezoelectric element to elastically deform the elastic support unit. The deformation of the elastic support unit changes a distance between the first reflector and the second reflector to change the oscillation wavelength of the light emitted from the light emitter.