Wavelength-variable laser
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.
1. An optical semiconductor device outputting a predetermined wavelength of laser light comprising:
a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction;
a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and
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,
wherein the optical semiconductor device is applied to a ridge-stripe type laser.
2. The optical semiconductor device according to claim 1 , further comprising a current constriction structure positioned at both sides of width direction of the quantum well active layer, wherein
the electric-field-distribution-control layer is formed to overlap with the current constriction structure in the thickness direction.
3. The optical semiconductor device according to claim 1 , wherein
the semiconductor layers constituting the electric-field-distribution-control layer are constituted by a first semiconductor layer made from semiconductor material having band gap energy that is the same as the n-type cladding layer and a second semiconductor layer made from semiconductor material having band gap energy greater than the barrier layer constituting the quantum well active layer.
4. The optical semiconductor device according to claim 3 , wherein
the first semiconductor layer is made from InP, and
the second semiconductor layer is made from III-V group compound semiconductor including an As atom and a P atom as composition.
5. The optical semiconductor device according to claim 4 , wherein
the second semiconductor layer is made from GaInAsP, and
a sum of layer thicknesses of the second semiconductor layers constituting the electric-field-distribution-control layer is equal to or smaller than 1 μm.
6. The optical semiconductor device according to claim 5 , wherein band gap composition wavelength of GaInAsP constituting the second semiconductor layer is equal to or greater than 1 μm.