Abstract: The present disclosure relates to an optical alignment compensation system for a gas detection system, in particular, to an integrated alignment compensation system for an open-path gas sensing system. The optical alignment compensation system of the disclosure is able to compensate for unwanted drifts of a retroreflector. The optical alignment system comprises an array of transceiver pairs, wherein each transceiver pair is configured to transmit and receive light with an optical spectrum in an absorption region of a gas to be detected. Further, it comprises a retroreflector arranged at a nominal position and configured to reflect the light. Further, it comprises an optical element arranged and configured to direct the light from at least one of the transceiver pairs along an optical path through the gas to the retroreflector, to receive the light reflected by the retroreflector along the optical path, and to direct the reflected light to the respective transceiver pair.

Abstract: A silicon-based photonic chip is provided that includes an interface for optically coupling the photonic chip to an optical fiber or an optical fiber assembly. The interface includes: a single-mode waveguide configured to guide light and to provide a first light beam; a first optical element configured to expand the light beam in a first direction in-plane of the photonic chip, thereby providing an expanded light beam; and a second optical element configured to deflect and to further expand the expanded light beam in a second direction, thereby providing an output light beam from the photonic chip. Also provided are methods for fabricating such a photonic chip.

Abstract: An avalanche photodiode (APD) device, in particular, a lateral separate absorption charge multiplication (SACM) APD device, and a method for its fabrication is provided. The APD device comprises a first contact region and a second contact region formed in a semiconductor layer. Further, the APD device comprises an absorption region formed on the semiconductor layer, wherein the absorption region is at least partly formed on a first region of the semiconductor layer, wherein the first region is arranged between the first contact region and the second contact region. The APD device further includes a charge region formed in the semiconductor layer between the first region and the second contact region, and an amplification region formed in the semiconductor layer between the charge region and the second contact region. At least the absorption region is curved on the semiconductor layer.

Abstract: A method is provided for fabricating an avalanche photodiode (APD) device, in particular, a separate absorption charge multiplication (SACM) APD device. The method includes forming a first contact region and a second contact region in a semiconductor layer. Further, the method includes forming a first mask layer above at least a first contact region of the semiconductor layer adjacent to the first contact region, and forming a second mask layer above and laterally overlapping the first mask layer. Thereby, a mask window is defined by the first mask layer and the second mask layer, and the first mask layer and/or the second mask layer are formed above a second contact region of the semiconductor layer adjacent to the second contact region.

Abstract: A monolithic integrated electro-optical phase modulator, a Mach-Zehnder modulator including one or more of the phase modulators, and method for fabricating the phase modulator by III-V-on-silicon semiconductor processing are provided. The phase modulator includes a silicon-based n-type substrate base layer, and a III-V n-type ridge waveguide for propagating light, wherein the ridge waveguide protrudes from and extends along the n-type substrate base layer. Further, the phase modulator includes one or more insulating layers provided on the ridge waveguide, wherein the one or more insulating layers have together a thickness of 1-100 nm, and a silicon-based p-type top cover layer provided on the one or more insulating layers at least above the ridge waveguide.

Abstract: A silicon-based photonic chip is provided that includes an interface for optically coupling the photonic chip to an optical fiber or an optical fiber assembly. The interface includes: a single-mode waveguide configured to guide light and to provide a first light beam; a first optical element configured to expand the light beam in a first direction in-plane of the photonic chip, thereby providing an expanded light beam; and a second optical element configured to deflect and to further expand the expanded light beam in a second direction, thereby providing an output light beam from the photonic chip. Also provided are methods for fabricating such a photonic chip.

Abstract: A method is provided for fabricating an avalanche photodiode (APD) device, in particular, a separate absorption charge multiplication (SACM) APD device. The method includes forming a first contact region and a second contact region in a semiconductor layer. Further, the method includes forming a first mask layer above at least a first contact region of the semiconductor layer adjacent to the first contact region, and forming a second mask layer above and laterally overlapping the first mask layer. Thereby, a mask window is defined by the first mask layer and the second mask layer, and the first mask layer and/or the second mask layer are formed above a second contact region of the semiconductor layer adjacent to the second contact region.

Abstract: A monolithic integrated electro-optical phase modulator, a Mach-Zehnder modulator including one or more of the phase modulators, and method for fabricating the phase modulator by III-V-on-silicon semiconductor processing are provided. The phase modulator includes a silicon-based n-type substrate base layer, and a III-V n-type ridge waveguide for propagating light, wherein the ridge waveguide protrudes from and extends along the n-type substrate base layer. Further, the phase modulator includes one or more insulating layers provided on the ridge waveguide, wherein the one or more insulating layers have together a thickness of 1-100 nm, and a silicon-based p-type top cover layer provided on the one or more insulating layers at least above the ridge waveguide.

Abstract: An avalanche photodiode (APD) device, in particular, a lateral separate absorption charge multiplication (SACM) APD device, and a method for its fabrication is provided. The APD device comprises a first contact region and a second contact region formed in a semiconductor layer. Further, the APD device comprises an absorption region formed on the semiconductor layer, wherein the absorption region is at least partly formed on a first region of the semiconductor layer, wherein the first region is arranged between the first contact region and the second contact region. The APD device further includes a charge region formed in the semiconductor layer between the first region and the second contact region, and an amplification region formed in the semiconductor layer between the charge region and the second contact region. At least the absorption region is curved on the semiconductor layer.

Abstract: A solid-state device for photo detection, in general, of terahertz radiation is disclosed. One aspect is a detector device comprising a body having a photoconductive material, a first antenna element connected to a first portion of the body, and a second antenna element connected to a second portion of the body. The first antenna element and the second antenna element are arranged to induce an electric field in the body in response to an incident signal. Further, the device has a waveguide arranged to couple light into the photoconductive material via a coupling interface between the waveguide and the body, where the coupling interface faces away from the first portion and the second portion of the body and is closer to the first portion than to the second portion.

Abstract: An electrically-operated semiconductor laser device and method for forming the laser device are provided. The laser device includes a fin structure to which a waveguide is optically coupled. The waveguide is optically coupled to passive waveguides at either end thereof. The fin structure includes an array of fin elements, each fin element comprising Group III-V materials.

Abstract: The disclosed technology relates to the development of a monolithic active electro-optical device. The electro-optical device may be fabricated using the so-called nanoridge aspect ratio trapping (ART) approach. In one aspect, the disclosed technology is directed to a monolithic integrated electro-optical device, which comprises a III-V-semiconductor-material ridge structure arranged on a Si-based support region.

Abstract: The disclosed technology relates to the development of a monolithic active electro-optical device. In some embodiments, the electro-optical device may be fabricated using the so-called nanoridge aspect ratio trapping (ART) approach. In one aspect, the electro-optical device is a monolithic integrated electro-optical device comprising a first-conductivity-type Si-based support region and a III-V-semiconductor-material ridge structure extending from the Si-based support region, wherein the ridge structure contains a recombination region. Furthermore, the device comprises a III-V-semiconductor capping layer having a higher band-gap than that of the III-V semiconductor material of the ridge structure and being formed on an outer surface of the ridge structure.

Abstract: A III-V semiconductor waveguide nanoridge structure having a narrow supporting base with a freestanding wider body portion on top, is disclosed. In one aspect, the III-V waveguide includes a PIN diode. The waveguide comprises a III-V semiconductor waveguide core formed in the freestanding wider body portion; at least one heterojunction incorporated in the III-V semiconductor waveguide core; a bottom doped region of a first polarity positioned at a bottom of the narrow supporting base, forming a lower contact; and an upper doped region of a second polarity, forming an upper contact. The upper contact is positioned in at least one side wall of the freestanding wider body portion.

Abstract: Example embodiments relate to active-passive waveguide photonic systems. An example embodiment includes a monolithic integrated active/passive waveguide photonic system. The system includes a substrate having positioned thereon at least one active waveguide and at least one passive waveguide. The at least one active waveguide and the at least one passive waveguide are monolithically integrated and are arranged for evanescent wave coupling between the waveguides. The at least one active waveguide and the at least one passive waveguide are positioned so that at least a portion of each waveguide does not overlap the other waveguide, both in a height direction and in a lateral direction with respect to the substrate.

Abstract: Example embodiments relate to monolithic III-V/Si waveguide phase modulators. One embodiment includes a monolithic integrated phase modulator that includes a waveguide for propagating light. The waveguide for propagating light includes a waveguide base made of a first conductivity type Si-based semiconductor material. The waveguide for propagating light also includes at least one groove formed in a surface of the waveguide base. Further, the waveguide for propagating light includes an epitaxial region formed on the waveguide base in the at least one groove. The epitaxial region is made of a second conductivity type III-V semiconductor material. The waveguide base and the epitaxial region form a monolithically integrated junction diode that is a phase modulation region for light propagated through the waveguide.

Abstract: Example embodiments relate to an electro-optical device that includes a vertical p-i-n diode waveguide. The electro-optical device includes a waveguide portion adapted for propagating a multimode wave, the waveguide portion including an intrinsic semiconductor region of the vertical p-i-n diode, a first contact and a second contact for electrically contacting a first electrode and a second electrode of the vertical p-i-n diode. The device also includes an input section for coupling radiation into the waveguide portion and an output section for coupling radiation out of the waveguide portion. The input section, the output section, and the waveguide portion are configured to support a multimode interference pattern for the multimode wave with an optical field with a lateral inhomogeneous spatial distribution in the waveguide portion including regions with higher optical field intensity and regions with lower optical field intensity. The second contact physically contacts the second electrode.

Abstract: A III-V semiconductor waveguide nanoridge structure having a narrow supporting base with a freestanding wider body portion on top, is disclosed. In one aspect, the III-V waveguide includes a PIN diode. The waveguide comprises a III-V semiconductor waveguide core formed in the freestanding wider body portion; at least one heterojunction incorporated in the III-V semiconductor waveguide core; a bottom doped region of a first polarity positioned at a bottom of the narrow supporting base, forming a lower contact; and an upper doped region of a second polarity, forming an upper contact. The upper contact is positioned in at least one side wall of the freestanding wider body portion.

Abstract: A solid-state device for photo detection, in general, of terahertz radiation is disclosed. One aspect is a detector device comprising a body having a photoconductive material, a first antenna element connected to a first portion of the body, and a second antenna element connected to a second portion of the body. The first antenna element and the second antenna element are arranged to induce an electric field in the body in response to an incident signal. Further, the device has a waveguide arranged to couple light into the photoconductive material via a coupling interface between the waveguide and the body, where the coupling interface faces away from the first portion and the second portion of the body and is closer to the first portion than to the second portion.

Abstract: Example embodiments relate to an electro-optical device that includes a vertical p-i-n diode waveguide. The electro-optical device includes a waveguide portion adapted for propagating a multimode wave, the waveguide portion including an intrinsic semiconductor region of the vertical p-i-n diode, a first contact and a second contact for electrically contacting a first electrode and a second electrode of the vertical p-i-n diode. The device also includes an input section for coupling radiation into the waveguide portion and an output section for coupling radiation out of the waveguide portion. The input section, the output section, and the waveguide portion are configured to support a multimode interference pattern for the multimode wave with an optical field with a lateral inhomogeneous spatial distribution in the waveguide portion including regions with higher optical field intensity and regions with lower optical field intensity. The second contact physically contacts the second electrode.