An optical waveguide structure includes a lower cladding layer positioned on a substrate; an optical guide layer positioned on the lower cladding layer; an upper cladding layer positioned on the optical guide layer; and a heater positioned on the upper cladding layer. The lower cladding layer, the optical guide layer, and the upper cladding layer constitute a mesa structure. The optical guide layer has a lower thermal conductivity than the upper cladding layer. An equation “W.sub.wg≤W.sub.mesa≤3×W.sub.wg” is satisfied, wherein W.sub.mesa represents a mesa width of the mesa structure, and W.sub.wg represents a width of the optical guide layer. The optical guide layer occupies one-third or more of the mesa width in a width direction of the mesa structure.

An optical waveguide structure includes a lower cladding layer positioned on a substrate; an optical guide layer positioned on the lower cladding layer; an upper cladding layer positioned on the optical guide layer; and a heater positioned on the upper cladding layer. The lower cladding layer, the optical guide layer, and the upper cladding layer constitute a mesa structure. The optical guide layer has a lower thermal conductivity than the upper cladding layer. An equation “W.sub.wg≤W.sub.mesa≤3×W.sub.wg” is satisfied, wherein W.sub.mesa represents a mesa width of the mesa structure, and W.sub.wg represents a width of the optical guide layer. The optical guide layer occupies one-third or more of the mesa width in a width direction of the mesa structure.

A PIC has first, second and third elements fabricated on a common substrate. The first element includes a structure supporting efficient coupling of one or more free-space optical modes of incident light into one or more waveguide guided optical modes. The second element includes an on-chip interferometer having an input optically coupled to the waveguide guided optical modes; one or more arms; one or more outputs; and a phase tuner configured to change optical path length in one or more of the arms. The third element includes one or more light detecting structures optically coupled to the one or more outputs of the second element, such that variation in optical power in the one or more outputs is detected, allowing an assessment of coherence characterizing the light incident on the first element of the PIC to be provided.

An optical device for an optical sensor comprises a gain element of a semiconductor laser, a wavelength selective feedback element, and a sensing element. At least part of the wavelength selective feedback element and the sensing element are arranged in a common sensor package. The gain element is arranged to generate and amplify an optical signal. The gain element and the wavelength selective feedback element form at least part of an external cavity of the semiconductor laser, thereby providing a feedback mechanism to sustain a laser oscillation depending on the optical signal. The wavelength selective feedback element is arranged to couple out a fraction of the optical signal and direct said fraction of the optical signal towards the sensing element to probe a physical property of the sensing element.

An optical device for an optical sensor comprises a gain element of a semiconductor laser, a wavelength selective feedback element, and a sensing element. At least part of the wavelength selective feedback element and the sensing element are arranged in a common sensor package. The gain element is arranged to generate and amplify an optical signal. The gain element and the wavelength selective feedback element form at least part of an external cavity of the semiconductor laser, thereby providing a feedback mechanism to sustain a laser oscillation depending on the optical signal. The wavelength selective feedback element is arranged to couple out a fraction of the optical signal and direct said fraction of the optical signal towards the sensing element to probe a physical property of the sensing element.

A QCL may include a substrate, an emitting facet, and semiconductor layers adjacent the substrate and defining an active region. The active region may have a longitudinal axis canted at an oblique angle to the emitting facet of the substrate. The QCL may include an optical grating being adjacent the active region and configured to emit one of a CW laser output or a pulsed laser output through the emitting facet of substrate.

In some implementations, a thermally-controlled photonic structure may include a suspended region that is suspended over a substrate; a plurality of bridge elements connected to the suspended region and configured to suspend the suspended region over the substrate, where a plurality of openings are defined between the plurality of bridge elements; and at least one heater element having a modulated width disposed on the suspended region. The at least one heater element having the modulated width may include at least one section of a greater width and at least one section of a lesser width. The at least one section of the greater width may be in alignment with an opening of the plurality of openings and the at least one section of the lesser width may be in alignment with a bridge element of the plurality of bridge elements.

An optical device may include a substrate and vertical-cavity surface-emitting lasers (VCSELs) on the substrate. The optical device may also include a coupling layer over the substrate and that includes optical guides aligned with the VCSELs to guide outputs thereof from a vertical path direction to a lateral path direction. The optical device also includes controllable delay elements, each controllable delay element associated with a respective optical guide, and a controller coupled to the controllable delay elements.

A quantum-cascade laser element includes: a semiconductor substrate; a semiconductor laminate formed on the semiconductor substrate to include a ridge portion configured to include an active layer having a quantum-cascade structure; an embedding layer including a first portion formed on a side surface of the ridge portion, and a second portion extending from an edge portion of the first portion on a side of the semiconductor substrate along a width direction of the semiconductor substrate; a metal layer formed on a top surface of the ridge portion, on the first portion, and on the second portion; and a dielectric layer disposed between the second portion and the metal layer. The dielectric layer is formed such that a part of the second portion is exposed from the dielectric layer. The metal layer is in contact with the second portion at the part.

Self-organizing patterns with micrometer-scale feature sizes are promising for the large area fabrication of photonic devices and scattering layers in optoelectronics. Pattern formation would ideally occur in the active semiconductor to avoid the need for further processing steps. The present disclosure includes approaches to form period patterns in single layers of organic semiconductors by an annealing process. When heated, a crystallization front propagates across the film, producing a sinusoidal surface structure with wavelengths comparable to that of near-infrared light. These surface features form initially in the amorphous region within a micron of the crystal growth front, likely due to competition between crystal growth and surface mass transport. The pattern wavelength can be tuned by varying film thickness and annealing temperature, millimeter scale domain sizes are obtained. Aspects of the disclosure can be exploited for self-assembly of microstructured organic optoelectronic devices, for example.