A method of manufacturing an optical semiconductor element includes: stacking a plurality of compound semiconductor layers on a first substrate containing a compound semiconductor; dividing the first substrate into small pieces; forming terraces, grooves, walls, and a first mesa for a waveguide on a second substrate containing silicon; jointing at least one small piece to the second substrate after the forming; wet-etching the first substrate so as to expose the compound semiconductor layers after the jointing; and forming a second mesa opposite to the first mesa from the compound semiconductor layers; wherein the grooves are formed on both sides of the first mesa, the terraces are formed on both sides of the first mesa and the grooves, and the walls are arranged in an extending direction of each groove.

Externally-strained devices such as LED and FET structures as discussed herein may have strain applied before or during their being coupled to a housing or packaging substrate. The packaging substrate may also be strained prior to receiving the structure. The strain on the devices enables modulation of light intensity, color, and electrical currents in some embodiments, and in alternate embodiments, enables a fixed strain to be induced and maintained in the structures.

A ridge structure (9) having a ridge lower part (6), a ridge upper part (8) above the ridge lower part (6) and having a larger width than the ridge lower part (6), is formed on a semiconductor substrate (1). A recess (11) of the ridge structure (9), where the ridge lower part (6) is laterally set back from the ridge upper part (8) due to a difference in width between the ridge upper part (8) and the ridge lower part t (6), is completely filled with an insulating film (10) by an atomic layer deposition method to form a protrusion (19) from the semiconductor substrate (1), the ridge structure (9), and the insulating film (10) without any step in a side face of the protrusion (19).

An optical full-field transmitter for an optical communications network includes a primary laser source configured to provide a narrow spectral linewidth for a primary laser signal, and a first intensity modulator in communication with a first amplitude data source. The first intensity modulator is configured to output a first amplitude-modulated optical signal from the laser signal. The transmitter further includes a first phase modulator in communication with a first phase data source and the first amplitude-modulated optical signal. The first phase modulator is configured to output a first two-stage full-field optical signal. The primary laser source has a structure based on a III-V compound semiconductor.

An apparatus is configured to operate in a single fundamental transverse mode and the apparatus includes a waveguide layer between an n-doped cladding layer and a p-doped cladding layer. The waveguide layer includes a first waveguide part, and an active layer located between the first waveguide part and the p-doped cladding layer, the active layer being asymmetrically within the waveguide layer closer to the p-doped cladding layer than the n-doped cladding layer. The refractive index of the n-doped cladding layer being equal to or larger than the p-doped cladding layer. A first end of the first waveguide part is adjacent to the n-doped cladding layer. A second end of the first waveguide part is adjacent to a first end of the active layer. A desired donor density is doped in the first waveguide part for controlling the carrier density dependent internal optical loss in the first waveguide part at high injection levels.

A method of manufacturing an optical semiconductor element includes: stacking a plurality of compound semiconductor layers on a first substrate containing a compound semiconductor; dividing the first substrate into small pieces; forming terraces, grooves, walls, and a first mesa for a waveguide on a second substrate containing silicon; jointing at least one small piece to the second substrate after the forming; wet-etching the first substrate so as to expose the compound semiconductor layers after the jointing; and forming a second mesa opposite to the first mesa from the compound semiconductor layers; wherein the grooves are formed on both sides of the first mesa, the terraces are formed on both sides of the first mesa and the grooves, and the walls are arranged in an extending direction of each groove.

Externally-strained devices such as LED and FET structures as discussed herein may have strain applied before or during their being coupled to a housing or packaging substrate. The packaging substrate may also be strained prior to receiving the structure. The strain on the devices enables modulation of light intensity, color, and electrical currents in some embodiments, and in alternate embodiments, enables a fixed strain to be induced and maintained in the structures.

A tunable laser that includes an array of parallel optical amplifiers is described. The laser may also include an intracavity NM coupler that couples power between a cavity mirror and the array of parallel optical amplifiers. Phase adjusters in optical paths between the NM coupler and the optical amplifiers can be used to adjust an amount of power output from M1 ports of the NM coupler. A tunable wavelength filter is incorporated in the laser cavity to select a lasing wavelength.

A ridge structure (9) having a ridge lower part (6), a ridge upper part (8) above the ridge lower part (6) and having a larger width than the ridge lower part (6), is formed on a semiconductor substrate (1). A recess (11) of the ridge structure (9), where the ridge lower part (6) is laterally set back from the ridge upper part (8) due to a difference in width between the ridge upper part (8) and the ridge lower part t (6), is completely filled with an insulating film (10) by an atomic layer deposition method to form a protrusion (19) from the semiconductor substrate (1), the ridge structure (9), and the insulating film (10) without any step in a side face of the protrusion (19).

According to a first aspect, the present disclosure relates to a semiconductor sub-assembly comprising a semiconductor device comprising: a semi-insulating substrate (201); a first section (210) configured to emit light; at least a second section (220) configured to modulate light emitted by said first section (210); wherein said first section (210) and said at least second section (220) are monolithically integrated on said semi-insulating substrate (201) and have a common optical waveguide (205); said first section (210) forms a first vertical PIN junction with a first electrode (212) and a second electrode (214) on said semi-insulating substrate (201); said second section (220) forms a second vertical PIN junction with a first electrode (222) and a second electrode (224) on said semi-insulating substrate (201); an electric resistance between said first electrode (212) of said first section (210) and said first electrode (222) of said second section (220) is superior to about 50 ohms; and an electric resistance between said second electrode (214) of said first section (210) and said second electrode (224) of said second section (220) is superior to about 50 ohms.