An optical integrated device includes a substrate and a waveguide that has a hollow structure. The waveguide includes a first waveguide and a second waveguide that is optically coupled to the first waveguide and that has a smaller relative refractive index difference than that of the first waveguide and converts a mode diameter to a mode diameter of an optical fiber in accordance with travelling of light. The optical integrated device includes a dent portion that is formed in the vicinity of the dicing line on the substrate such that the width of the output end surface is smaller than the core width of the optical fiber that is optically coupled to the output end surface in the state in which the dicing end surface of the substrate protrudes farther than the output end surface of the second waveguide in the axial direction of the optical waveguide.

A device providing efficient transformation between an initial optical mode and a second optical mode includes first, second and third elements fabricated on a common substrate. The first element includes first and second active sub-layers supporting initial and final optical modes with efficient mode transformation therebetween. The second element includes a passive waveguide structure supporting a second optical mode. The third element, at least partly butt-coupled to the first element, includes an intermediate waveguide structure supporting an intermediate optical mode. If the final optical mode differs from the second optical mode by more than a predetermined amount, a tapered waveguide structure in the second or third elements facilitates efficient transformation between the intermediate optical mode and the second optical mode. Precise alignment of sub-elements formed in one of the elements, relative to sub-elements formed in another one of the elements, is defined using lithographic alignment marks.

A splitter. In some embodiments, the splitter includes an input waveguide; a first output waveguide; a second output waveguide; a first internal waveguide, connected to the input waveguide and to the first output waveguide, and a second internal waveguide, coupled to the first internal waveguide and connected to the second output waveguide. The splitter may be configured, when fed, at the input waveguide, power in a fundamental mode of the input waveguide or power in a first order spatial mode of the input waveguide: to transmit at least 80% of the power in the fundamental mode to the first output waveguide, and to transmit at least 80% of the power in the first order spatial mode to the second output waveguide.

A photodetector has a substrate, a light input layer formed as a first semiconductor over the substrate, the first semiconductor being transparent to a wavelength being used, and a light absorption layer formed as a second semiconductor on the light input layer, the second semiconductor having a bandgap smaller than that of the first semiconductor. The light absorption layer has a first region doped with a first conductivity-type impurity, a second region doped with a second conductive-type impurity different from the first conductive-type impurity, and an undoped region between the first region and the second region. The first region, the undoped region and the second region are arranged in a direction parallel to the substrate. The light absorption layer has a region having an effective refractive index higher than the rest of the light absorption layer between the first region and the second region.

An optical waveguide device has a function of removing or suppressing a higher-order mode component of propagating light. The optical waveguide device includes a curved waveguide having a curved shape where a curvature continuously changes. A first waveguide is coupled to one end of the curved waveguide and a second waveguide is coupled to the other end of the curved waveguide. A curvature of the first waveguide and the curvature of the curved. waveguide are equal to each other in a coupling point in which the first waveguide is coupled to the curved waveguide, and a curvature of the second waveguide and the curvature of the curved waveguide are equal to each other in a coupling point in which the second waveguide is coupled to the curved waveguide.

A photonic module, comprising a first waveguide; a second waveguide, disposed on an opposing side of the first waveguide to a substrate; and, a coupling section. One of the first waveguide and the second waveguide is formed of crystalline silicon. The other of the first waveguide and the second waveguide is formed of amorphous silicon. The coupling section is configured to couple light between the first waveguide and the second waveguide. Such a silicon photonic module has enhanced coupling and transmission properties in contrast to conventional modules.

A semiconductor arrangement is provided and includes a first dielectric layer over an optical device. A first metallization layer is over the first dielectric layer, and a first conductive line is in the first metallization layer. A first conductive via is in the first metallization layer and contacts the first conductive line. A second metallization layer is over the first metallization layer. A second conductive line is in the second metallization layer and contacts the first conductive via at a first interface. A heater is over the optical device and has a lowermost surface below the first interface and an uppermost surface above the first interface.

A waveguide structure and a method for splitting light is described. The method may include optically coupling a first waveguide and a second waveguide, where the optical coupling may be wavelength insensitive. The widths of the first and second waveguides may be non-adiabatically varying and the optical coupling may be asymmetric between the first and second waveguides. A gap between the first and second waveguides may also be varied non-adiabatically and the gap may depend on the widths of the first and second waveguides. The optical coupling between the first and second waveguides may also occur in the approximate wavelength range of 800 nanometers to 1700 nanometers.

Embodiments presented in this disclosure generally relate to an optical device having a grating coupler for redirection of optical signals. One embodiment includes a grating coupler. The grating coupler generally includes a waveguide layer, a thickness of a waveguide layer portion of the waveguide layer being tapered, the thickness defining a direction, and a grating layer disposed above the waveguide layer and perpendicular to the direction where at least a grating layer portion of the grating layer overlaps the waveguide layer portion of the waveguide layer along the direction. Some embodiments are directed to grating coupler implemented with material layers above and a reflector layer below a grating layer, facilitating redirection and confinement of light that improves coupling loss and bandwidth. The material layers and reflector layer above and below the grating layer may be implemented with or without the waveguide layer being tapered.

An integrated on-chip polarization rotator splitter (26) comprises a waveguide polarization rotator (54) having a first and a second layer (62) that form a rib waveguide (66) together and are both made of silicon nitride. The first layer (62) has a first, a second and a third section. The first layer (64) has a first width (w.sub.1) that increases in the first section (S1), is constant in the second section (S1) and decreases in the third section (S3). The second layer (64) has a second width (w.sub.2) that continuously increases. The polarization rotator splitter (26) further includes a waveguide polarization splitter (61) comprising a first strip waveguide (71) and a second strip waveguide (72) that are separated by a gap (74). The first and second strip waveguides (71, 72) are also made of silicon nitride. The first and second strip waveguide (71, 72) form an asymmetric evanescent direction coupler.