A mode converter provided in the present invention includes an input multimode waveguide, an output multimode waveguide, and a first conversion waveguide, where the input multimode waveguide is configured to receive a first signal which mode is a first mode; the first conversion waveguide has an input coupling waveguide with a first effective refractive index, and has an output coupling waveguide with a second effective refractive index: the first conversion waveguide is configured to perform, by using the input coupling waveguide, evanescent wave coupling on the first signal that is in the first mode and that is transmitted in the input multimode waveguide, and couple the first signal to the second mode of the output multimode waveguide by using the output coupling waveguide, so as to obtain the first signal in the second mode; and the output multimode waveguide is configured to output the first signal in the second mode.

A mode converter provided in the present invention includes an input multimode waveguide, an output multimode waveguide, and a first conversion waveguide, where the input multimode waveguide is configured to receive a first signal which mode is a first mode; the first conversion waveguide has an input coupling waveguide with a first effective refractive index, and has an output coupling waveguide with a second effective refractive index: the first conversion waveguide is configured to perform, by using the input coupling waveguide, evanescent wave coupling on the first signal that is in the first mode and that is transmitted in the input multimode waveguide, and couple the first signal to the second mode of the output multimode waveguide by using the output coupling waveguide, so as to obtain the first signal in the second mode; and the output multimode waveguide is configured to output the first signal in the second mode.

Multilevel leaky-mode optical elements, including reflectors, polarizers, and beamsplitters. Some of the elements have a plurality of spatially modulated periodic layers coupled to a substrate. For infrared applications, the optical elements may have a bandwidth larger than 600 nanometers.

Multilevel leaky-mode optical elements, including reflectors, polarizers, and beamsplitters. Some of the elements have a plurality of spatially modulated periodic layers coupled to a substrate. For infrared applications, the optical elements may have a bandwidth larger than 600 nanometers.

An apparatus includes an input coupler configured to receive light excited by a light source. A near-field transducer (NFT) is positioned at a media-facing surface of a write head. A layered waveguide is positioned between the input coupler and the NFT and configured to receive the light output from the input coupler in a transverse electric (TE) mode and deliver the light to the NFT in a transverse magnetic (TM) mode. The layered waveguide comprises a first layer extending along a light-propagation direction. The first layer is configured to receive light from the input coupler. The first layer tapers from a first cross track width to a second cross track width where the second cross track width is narrower than the first cross track width. The layered waveguide includes a second layer that is disposed on the first layer. The second layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction. The cross sectional area of the second layer is smaller proximate to the input coupler and larger proximate to the NFT.

An apparatus includes an input coupler configured to receive light excited by a light source. A near-field transducer (NFT) is positioned at a media-facing surface of a write head. A layered waveguide is positioned between the input coupler and the NFT and configured to receive the light output from the input coupler in a transverse electric (TE) mode and deliver the light to the NFT in a transverse magnetic (TM) mode. The layered waveguide comprises a first layer extending along a light-propagation direction. The first layer is configured to receive light from the input coupler. The first layer tapers from a first cross track width to a second cross track width where the second cross track width is narrower than the first cross track width. The layered waveguide includes a second layer that is disposed on the first layer. The second layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction. The cross sectional area of the second layer is smaller proximate to the input coupler and larger proximate to the NFT.

A right-angle bending waveguide includes a circular-hole-type square-lattice photonic crystal (PhC) and a single compensation scattering rod having a low refractive index. The right-angle bending waveguide is a PhC formed from first dielectric rods having a low refractive index arranged in a background dielectric having a low refractive index according to a square lattice. In the PhC, one row and one column of the first dielectric rods having a high refractive index are removed to form the right-angle bending waveguide. A second dielectric rod having a high refractive index is arranged at a corner of the right-angle bending waveguide. The second dielectric rod is the compensation scattering rod or an air hole. The first dielectric rods are circular rods having the low refractive index or air holes. The right-angle bending waveguide having the circular-hole-type square-lattice PhC and the single compensation scattering rod having the low refractive index has extremely low reflectance and a very high transmission rate, facilitates large-scale optical path integration, and provides a broader space for PhC application.

A right-angle bending waveguide includes a circular-hole-type square-lattice photonic crystal (PhC) and a single compensation scattering rod having a low refractive index. The right-angle bending waveguide is a PhC formed from first dielectric rods having a low refractive index arranged in a background dielectric having a low refractive index according to a square lattice. In the PhC, one row and one column of the first dielectric rods having a high refractive index are removed to form the right-angle bending waveguide. A second dielectric rod having a high refractive index is arranged at a corner of the right-angle bending waveguide. The second dielectric rod is the compensation scattering rod or an air hole. The first dielectric rods are circular rods having the low refractive index or air holes. The right-angle bending waveguide having the circular-hole-type square-lattice PhC and the single compensation scattering rod having the low refractive index has extremely low reflectance and a very high transmission rate, facilitates large-scale optical path integration, and provides a broader space for PhC application.

A cross-shaped infrared polarized light bridge based on a photonic crystal waveguide. The present invention aims to provide a polarized light bridge that is small in structural size, high in polarization degree, convenient to integrate, and highly efficient, besides which, crosstalk is not caused at a cross intersection. The cross-shaped infrared polarized light bridge comprises a photonic crystal waveguide provided with a complete bandgap. The photonic crystal waveguide is in a cross shape. Waveguide defect dielectric columns are disposed in the photonic crystal cross-shaped waveguide. The waveguide defect dielectric columns are square defect dielectric columns (6) and round defect dielectric columns (7). The photonic crystal cross-shaped waveguide comprises a vertical TE waveguide, a horizontal TM waveguide, a TM optical signal input port (1), a TM output port (3), a TE optical signal input port (2), and a TE output port (4). The two input ports (1,2) of the photonic crystal waveguide separately input a TM optical signal and a TE optical signal. Mutual influence is not caused at a cross intersection position of light circuits formed by the TM wave and the TE wave in a shared central area. The input TM optical signal is output from the TM output port (3). The input TE optical signal is output from the TE output port (4).

A cross-shaped infrared polarized light bridge based on a photonic crystal waveguide. The present invention aims to provide a polarized light bridge that is small in structural size, high in polarization degree, convenient to integrate, and highly efficient, besides which, crosstalk is not caused at a cross intersection. The cross-shaped infrared polarized light bridge comprises a photonic crystal waveguide provided with a complete bandgap. The photonic crystal waveguide is in a cross shape. Waveguide defect dielectric columns are disposed in the photonic crystal cross-shaped waveguide. The waveguide defect dielectric columns are square defect dielectric columns (6) and round defect dielectric columns (7). The photonic crystal cross-shaped waveguide comprises a vertical TE waveguide, a horizontal TM waveguide, a TM optical signal input port (1), a TM output port (3), a TE optical signal input port (2), and a TE output port (4). The two input ports (1,2) of the photonic crystal waveguide separately input a TM optical signal and a TE optical signal. Mutual influence is not caused at a cross intersection position of light circuits formed by the TM wave and the TE wave in a shared central area. The input TM optical signal is output from the TM output port (3). The input TE optical signal is output from the TE output port (4).