A laminate (22) is formed on a semiconductor substrate (10). Two or more grooves (54) are formed in the laminate (22). A mesa (24) with two grooves among the two or more grooves (54) positioned on both sides is formed. An insulating resin film (30) is embedded into the two or more grooves (54). A first opening (32) is formed at the insulating resin film (30) embedded in one of the two or more grooves (54) and an electrode (46) extracted upward from a bottom surface (36) is formed. A first side surface (34) of the insulating resin film (30) is inclined in a forward tapered direction.

A method for on-silicon integration of a III-V-based material component includes providing a first substrate having a silicon-based optical layer including a waveguide, transferring a second substrate of III-V-based material on the optical layer, and forming the III-V component from the second substrate, so as to enable a coupling between the waveguide and the III-V component, by preserving a III-V-based material layer extending laterally. The method also includes forming by epitaxy from the III-V layer, an InP:Fe-based structure laterally bordering the III-V component, forming a layer including contacts configured to contact the III-V component, and transferring a third silicon-based substrate onto the layer including the contacts.

An optical semiconductor device includes an active layer having a plurality of quantum dot layers. The plurality of quantum dot layers include: a first quantum dot layer doped with a p-type impurity; and a second quantum dot layer doped with an n-type impurity and having an emission wavelength different from that of the first quantum dot layer.

A method includes receiving input light having an input wavelength in a first optical resonator for causing resonance of the input light in the first optical resonator. The first optical resonator includes a non-linear optical medium. The method also includes converting at least a portion of the input light to a combination of first output light having a first output wavelength that is different from the input wavelength and second output light having a second output wavelength that is different from the input wavelength and the first output wavelength by passing the input light through the non-linear optical medium. The method further includes causing resonance of the first output light and the second output light in a second optical resonator. A portion of the first optical resonator is coupled to a portion of the second optical resonator.

Provided are an electro-absorption modulator and an optical semiconductor device which are excellent in high extinction ratio characteristics and high-speed operation. The electro-absorption modulator includes: a semi-insulating semiconductor layer; a first electro-absorption modulator section including a first n-type semiconductor layer, a first absorption layer, and a first p-type semiconductor layer; a second electro-absorption modulator section including a second p-type semiconductor layer, a second absorption layer, and a second n-type semiconductor layer; a connection waveguide layer arranged between the first absorption layer and the second absorption layer; a first EA electrode electrically connected to the first p-type semiconductor layer and electrically connected to an outside; a second EA electrode electrically connected to the second n-type semiconductor layer and electrically connected to the outside; and a connection medium configured to electrically connect the first n-type semiconductor layer and the second p-type semiconductor layer to each other.

High bandwidth (e.g., >100 GHz) modulators and methods of fabricating such are provided. An EAM comprises a waveguide mesa comprising a continuous multi-quantum well (MQW) layer; a plurality of electrode segments disposed on the waveguide mesa; and a microstrip transmission line disposed on an insulating material layer and in electrical communication with the plurality of electrode segments via conducting bridges. The waveguide mesa comprises alternating active sections and passive sections. An electrode segment of the plurality of electrodes is disposed on a respective one of the active sections. Portions of the continuous MQW layer disposed in each of the active sections having an energy gap defining an active energy gap value. Portions of the continuous MQW layer disposed in each of the passive sections having an energy gap defining an passive energy gap value. The active energy gap value is less than the passive energy gap value.