Semiconductor optical device with a buried heterostructure (bh) having reduced parasitic capacitance and reduced inter-diffusion

A semiconductor laser, comprising:

• a semiconductor substrate;
• a buried mesa structure formed on the semiconductor substrate, the buried mesa structure including a first n-type InP cladding layer, an active region above the first n-type InP cladding layer, a grating disposed within the first n-type InP cladding layer below the active region, and a first p-type InP cladding layer above the active region;
• stacked side layers on each side of the buried mesa structure, the stacked side layers including an Fe-doped InP layer burying the buried mesa structure on each side and a second n-type InP cladding layer on the Fe-doped InP layer;
• a second p-type InP cladding layer above the mesa structure and the stacked side layers, wherein the second p-type cladding layer is a highly Zn-doped InP layer, wherein contact portions of the Fe-doped InP layer extend above the active region to contact the highly Zn-doped InP layer, and wherein the second n-type InP cladding layer is outside the contact portions of the Fe-doped InP layer and between a substantial portion of the Fe-doped InP layer and the highly Zn-doped InP layer;
• and
• a third p-type cladding layer on the second p-type cladding layer, wherein the third p-type cladding layer is a Zn-doped InGaAs layer.

A semiconductor optical modulator, comprising:

• a semiconductor substrate;
• a buried mesa structure formed on the semiconductor substrate, the buried mesa structure including a first n-type InP cladding layer, an active region above the first n-type InP cladding layer, and a first p-type InP cladding layer above the active region;
• stacked side layers on each side of the buried mesa structure, the stacked side layers including an Fe-doped InP layer burying the buried mesa structure on each side and a second n-type InP cladding layer on the Fe-doped InP layer;
• a second p-type InP cladding layer above the mesa structure and the stacked side layers, wherein the second p-type InP cladding layer is a highly Zn-doped InP layer, wherein contact portions of the Fe-doped InP layer extend above the active region to contact the second p-type InP cladding layer, and wherein the second n-type InP cladding layer is outside the contact portions of the Fe-doped InP layer and between a substantial portion of the Fe-doped InP layer and the highly Zn-doped InP layer;
• including a third p-type cladding layer on the second p-type cladding layer, wherein the third p-type cladding layer is a Zn-doped InGaAs layer;
• wherein a top mesa structure is formed by at least the p-type cladding layers and the second n-type cladding layer;
• an n-type metal layer on the bottom under the substrate and a p-type metal layer on the top and located in a contact window formed on the top mesa structure.