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.

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.

A terahertz polarization beam splitter based on a two-core negative curvature fiber is provided, which relates to the technical field of optical fiber communication. The polarization beam splitter includes: a base circular tube and core separation structures. Multiple large cladding tubes are internally tangent and connected to an inner wall of the base circular tube and arranged at equal intervals along a circumference of the inner wall of the base circular tube, and the multiple large cladding tubes are symmetrically distributed on the inner wall of the base circular tube. Embedded circular tubes are internally tangent and connected to inner walls of the multiple large cladding tubes respectively. The core separation structures are two in number.

A silicon photonic device includes a silicon-on-insulator substrate, a waveguide, and a plate. The silicon-on-insulator substrate includes a silicon layer and a silicon dioxide layer. The waveguide is disposed on the silicon-on-insulator substrate. The silicon dioxide layer at least partially overlays the waveguide. The plate exhibits metallic characteristics and is at least partially embedded in the silicon dioxide layer of the silicon-on-insulator substrate. The plate is spaced apart from the waveguide and is configured to mitigate transverse magnetic emission propagating through the waveguide.

A silicon photonic device includes a silicon-on-insulator substrate, a waveguide, and a plate. The silicon-on-insulator substrate includes a silicon layer and a silicon dioxide layer. The waveguide is disposed on the silicon-on-insulator substrate. The silicon dioxide layer at least partially overlays the waveguide. The plate exhibits metallic characteristics and is at least partially embedded in the silicon dioxide layer of the silicon-on-insulator substrate. The plate is spaced apart from the waveguide and is configured to mitigate transverse magnetic emission propagating through the waveguide.

An optical waveguide device includes first and second waveguides formed parallel to each other. The first waveguide includes a first rib and a first slab. The first slab is formed in a region between the first rib and the second waveguide. The second waveguide includes a second rib, a second slab and a third slab. The second rib is provided between the second slab and the third slab. The first and second slabs are integrally formed. At one end of the optical waveguide device, a first effective refractive index that indicates an effective refractive index of a TEi mode in the first waveguide is higher than a second effective refractive index that indicates an effective refractive index of a TEj mode in the second waveguide. At another end, the first effective refractive index is lower than the second effective refractive index.

An optical waveguide device includes first and second waveguides formed parallel to each other. The first waveguide includes a first rib and a first slab. The first slab is formed in a region between the first rib and the second waveguide. The second waveguide includes a second rib, a second slab and a third slab. The second rib is provided between the second slab and the third slab. The first and second slabs are integrally formed. At one end of the optical waveguide device, a first effective refractive index that indicates an effective refractive index of a TEi mode in the first waveguide is higher than a second effective refractive index that indicates an effective refractive index of a TEj mode in the second waveguide. At another end, the first effective refractive index is lower than the second effective refractive index.

A medical instrument is described that includes an optical source, an optical fiber, and a waveguide patterned upon a substrate. The optical fiber receives radiation from the optical source and includes a first segment and a second segment. The second segment is rotated about an optical axis relative to the first segment. The waveguide receives radiation from the optical source and guides a beam of radiation. The waveguide includes a first waveguide segment designed to impart a first differential group delay on the beam of radiation and a second waveguide segment designed to impart a second differential group delay on the beam of radiation. A sum of the first differential group delay and the second differential group delay is substantially zero.

A medical instrument is described that includes an optical source, an optical fiber, and a waveguide patterned upon a substrate. The optical fiber receives radiation from the optical source and includes a first segment and a second segment. The second segment is rotated about an optical axis relative to the first segment. The waveguide receives radiation from the optical source and guides a beam of radiation. The waveguide includes a first waveguide segment designed to impart a first differential group delay on the beam of radiation and a second waveguide segment designed to impart a second differential group delay on the beam of radiation. A sum of the first differential group delay and the second differential group delay is substantially zero.

A first waveguide and a second waveguide including a first layer and a second layer are provided. In a first longitudinal segment, the first layer gradually approaches a first waveguide in a first transverse direction. In a second longitudinal segment, the first and second waveguides are longitudinally oriented. In a third longitudinal segment, the first layer includes a length portion having a width in the first transverse direction that gradually decreases along the third longitudinal segment, and the second layer includes a length portion having a width in the first transverse direction that gradually increases along the third longitudinal segment.