A photonic device comprising: a support; an intermediate layer comprising at least one dielectric material and a first and second excess thickness of silicon separated from each other by a space; a first patterned silicon layer at least partially forming a waveguide, and first to fifth waveguide sections; a first dielectric layer covering the first silicon layer and a gain structure comprising at least one gain medium in contact with the first dielectric layer; the second and fourth wave guide sections, the first and second excess thicknesses of silicon, and the first and second ends of the gain structure forming a first and second optical transition zone between a hybrid laser waveguide, formed by a central portion of the gain structure, the space and the third waveguide section and the first and fifth waveguide sections respectively. The invention also relates to a method of fabricating such a photonic device.

An optical device that includes: a base layer; a first region supported by the base layer, the first region including a first plurality of quantum-confined nanostructures and having a first density of quantum-confined nanostructures; a second region supported by the base layer, the first and second regions being non-overlapping regions, the second region having a second density of quantum-confined nanostructures lower than the first density; and an optical confinement structure supported by the base layer and configured to guide at least one transverse optical mode between a first end and a second end of the optical confinement structure. The first region substantially overlaps with the at least one transverse optical mode, and the first density varies across a cross-section of the optical device.

A quantum cascade laser includes: a substrate having a principal surface, a back surface, and a substrate end face, the substrate end face extending along a reference plane intersecting a second direction which intersects the first direction; a semiconductor laminate having a laminate end face extending along the reference plane; a first electrode disposed on the semiconductor laminate; a second electrode disposed on the substrate; a first insulating film disposed on the laminate end face and the first electrode; a metal film disposed on the first insulating film, the laminate end face, the substrate end face, and the second electrode; and a second insulating film disposed on the first electrode, the second insulating film having a part on the first electrode between the metal film and the semiconductor laminate. On the first electrode, the second insulating film has a thickness larger than that of the first insulating film.

A laser including: a gain chip; an external cavity incorporating a Bragg grating; and a baseplate; wherein a first end of the gain chip has a high reflectivity facet forming a first end of the laser cavity; a second end of the gain chip has a low reflectivity facet; and a second part of the external cavity comprises a Bragg grating, supported by the baseplate, the temperature of the baseplate being maintained through a feedback loop; wherein the optical length of the external cavity is at least an order of magnitude greater than the optical length of the gain chip; wherein the Bragg grating is physically long and occupies a majority of the length of the external cavity and is apodized to control the sidemodes of the grating reflection.

A tunable laser including: an optical cavity including a first and second end mirrors, and a center mirror; a quantum well gain region between the end mirrors; and a transparent heat spreader bonded to the quantum well gain region; wherein the optical cavity is configured to generate resonant laser radiation between the end mirrors; the quantum well gain region includes at least one quantum well that is substantially aligned with an antinode of the resonant laser radiation and is located at a fixed distance to the center mirror; the distance from the first end mirror to the center mirror is optimized to maintain maximum output power, and the distance from the second end mirror to the center mirror is adjustable for tuning the laser to a desired output wavelength; the center mirror maintains an antinode of the resonant radiation at a fixed phase relationship with the center mirror.

A two-dimensional photonic-crystal surface-emitting laser includes: a two-dimensional photonic-crystal layer; an active layer provided on one surface side of the two-dimensional photonic-crystal layer; and a reflection layer provided on the other surface side of the two-dimensional photonic-crystal layer or on a side opposite to the two-dimensional photonic-crystal layer so as to be spaced apart from the two-dimensional photonic-crystal layer, wherein a distance d between surfaces of the two-dimensional photonic-crystal layer and the reflection layer facing each other is set such that a radiation coefficient difference ??.sub.v=(?.sub.v1??.sub.v0), which is a value obtained by subtracting a radiation coefficient ?.sub.v0 of a fundamental mode having the smallest loss from a radiation coefficient ?.sub.v1 of a first higher order mode having the second smallest loss among the light amplified in the two-dimensional photonic-crystal layer, is 1 cm.sup.?1 or more.

A method for sweeping an electromagnetic radiation source (12) to produce single mode operation having an optimized side-mode suppression ratio over a continuous range of wavelengths within a prescribed temporal profile, the electromagnetic radiation source is configured to output electromagnetic radiation at a given wavelength based upon parameters. The method includes determining a set of parameter combinations that satisfy a condition for a desired set of wavelengths and a maximum side mode suppression ratio over the range of wavelengths. The set of parameter combinations define sub-paths for transitioning from one wavelength to another wavelength. Combinations of select sub-paths provide a multivariate path for transitioning over the range of wavelengths. The method also includes controlling the semiconductor laser to emit electromagnetic radiation over the range of wavelengths by traversing the multivariate path in a desired manner.

A laser including: a gain chip; an external cavity incorporating a Bragg grating; and a baseplate; wherein a first end of the gain chip has a high reflectivity facet forming a first end of the laser cavity; a second end of the gain chip has a low reflectivity facet; and a second part of the external cavity comprises a Bragg grating, supported by the baseplate, the temperature of the baseplate being maintained through a feedback loop; wherein the optical length of the external cavity is at least an order of magnitude greater than the optical length of the gain chip; wherein the Bragg grating is physically long and occupies a majority of the length of the external cavity and is apodized to control the sidemodes of the grating reflection.

The inventive waveguide structure comprises a first waveguide region having a constant first width adapted to guide electromagnetic waves mode sustainably along its longitudinal axis; a second waveguide region adapted to guide electromagnetic waves mode sustainably along its longitudinal axis, wherein the longitudinal axis of the first waveguide region and the longitudinal axis of the second waveguide region form a common longitudinal axis of the waveguide structure, wherein a first end face of the first waveguide region and a first end face of the second waveguide region are aligned with each other, the width of the first end face of the second waveguide region corresponding to the first width, and the width of the second waveguide region along its longitudinal axis widens from the first end face to a second end face to a second width greater than the first width.

A quantum cascade laser includes: a semiconductor device portion having a substrate, a semiconductor laminate, and a semiconductor insulating portion, the semiconductor laminate having a principal surface, the substrate having a back surface and a substrate end face, the semiconductor laminate having a laminate end face, the semiconductor insulating portion and the substrate being arranged along a reference plane intersecting the second direction, the semiconductor device portion having a front end face and a rear end face, the front end face and the rear end face being arranged in the second direction, the rear end face including the substrate end face, and the substrate end face extending along the reference plane; a first electrode disposed on the semiconductor laminate; and a metal film disposed on the rear end face, the semiconductor insulating portion and the second electrode, the metal film being apart from the first electrode.