An optical semiconductor element includes a semiconductor substrate, a first laminated structure provided on a front surface of the semiconductor substrate, and a second laminated structure provided on the front surface of the semiconductor substrate, the first laminated structure includes a first quantum cascade region, the second laminated structure includes a dummy region having the same layer structure as the first quantum cascade region, a second quantum cascade region provided on the front surface of the semiconductor substrate via the dummy region, and one of the first quantum cascade region and the second quantum cascade region is a quantum cascade laser, and the other of the first quantum cascade region and the second quantum cascade region is a quantum cascade detector.

The present disclosure provides for laser integration into photonic platforms in which a first wafer, including a first substrate and a first insulator that includes a first plurality of dies that each include a first set of optical waveguides, is bonded to a second wafer, including a second substrate and a second insulator that includes a second plurality of dies that each include a second set of optical waveguides. The bond between the two wafers defines a wafer bond interface joining the first insulator with the second insulator and vertically aligning the first plurality of dies with the second plurality of dies such that respective first sets of optical waveguides are optically coupled with respective second sets of optical waveguides.

A QCL includes a semiconductor substrate and an active layer provided on the semiconductor substrate. The active layer has a cascade structure in which a unit laminate including a light emission layer which generates light and an injection layer to which electrons are transported from the light emission layer is laminated in multiple stages. The light emission layer and the injection layer each have a quantum well structure in which quantum well layers and barrier layers are alternately laminated. A separation layer including a separation quantum well layer having a layer thickness smaller than an average layer thickness of the quantum well layers included in the light emission layer and smaller than an average layer thickness of the quantum well layers included in the injection layer is provided between the light emission layer and the injection layer in the unit laminate.

A VCSEL device includes a substrate and a laser cavity that includes a gain section disposed between first and second reflectors. The VCSEL device is operable to emit light through a first end of the VCSEL device. The VCSEL device includes an anode surface mount contact and a cathode surface mount contact, each which is disposed at a second end of the VCSEL device opposite the first end of the VCSEL device.

A first conduction type first cladding layer and a second conduction type second cladding layer are arranged on the two sides in the vertical direction of a core portion having a multiple quantum-well structure, and a first conduction type third cladding layer and a second conduction type fourth cladding layer are arranged on the two sides in the horizontal direction of the core portion. A first electrode connected to the third cladding layer is formed. A second electrode connected to the fourth cladding layer is formed. A reverse bias is applied between the first and third cladding layers and the second and fourth cladding layers.

An optical semiconductor element includes: a semiconductor substrate that is semi-insulating; a columnar body that is formed on a front surface-side of the semiconductor substrate and configured to emit or receive light from the front surface-side; a front surface-side electrode that is connected to the columnar body; a back surface-side electrode formed on a back surface-side of the semiconductor substrate; and an electrically conductive member that is formed to penetrate through the semiconductor substrate to connect the front surface-electrode and the back surface-side electrode, and has a protruding portion protruding on the front surface-side of the semiconductor substrate.

A distributed feedback (DFB) laser that includes a substrate comprising a first surface and a second surface, wherein the substrate comprises silicon; a plurality of shallow trench isolations (STIs) located over the second surface of the substrate; a grating region located over the plurality of STIs and the substrate, wherein the grating region comprises a III-V semiconductor material; a non-intentional doping (NID) region located over the grating region; and a contact region located over the NID region.

A Dense Wavelength Division Multiplexing (DWDM) photonic integration circuit (PIC) that implements a DWDM system, such as a transceiver, is described. The DWDM PIC architecture includes photonic devices fully integrating on a single manufacturing platform. The DWDM PIC has a multi-wavelength optical laser, a quantum dot (QD) laser with integrated heterogeneous metal oxide semiconductor (H-MOS) capacitor, integrated on-chip. The multi-wavelength optical laser can be a symmetric comb laser that generates two equal outputs of multi-wavelength light. Alternatively, the DWDM PIC can be designed to interface with a stand-alone multi-wavelength optical laser that is off-chip. In some implementations, the DWDM PIC integrates multiple optimally designed photonic devices, such as a silicon geranium (SiGe) avalanche photodetector (APD), an athermal H-MOS wavelength splitter, a QD photodetector, and a heterogenous grating coupler. Accordingly, fabricating the DWDM PIC includes a unique III-V to silicon bonding process, which is adapted for its use of SiGe APDs.

A method of transfer printing. The method comprising: providing a precursor photonic device, comprising a substrate and a bonding region, wherein the precursor photonic device includes one or more alignment marks located in or adjacent to the bonding region; providing a transfer die, said transfer die including one or more alignment marks; aligning the one or more alignment marks of the precursor photonic device with the one or more alignment marks of the transfer die; and bonding at least a part of the transfer die to the bonding region.

The present invention is characterized by comprising: forming a stacked structure in which a lower cladding layer, an active layer and an upper cladding layer are stacked on an InP substrate in a shape having a mesa stripe structure; forming a first insulation film on the stacked structure by a sputtering method; forming a second insulation film thinner than the first insulation film, on the first insulation film by a plasma CVD method at a film forming temperature higher than that when the first insulation film has been formed; and forming a first electrode on the upper cladding layer, and forming a second electrode on a back surface of the InP substrate.