A light polarizing element include: a first port waveguide; two second port waveguides; and a multi-mode interference waveguide optically connected to the first port waveguide and the two second port waveguides, the multi-mode interference waveguide having at least one slit formed therein, the at least one slit having a shape that enables the multi-mode interference wave guide to give different effective refractive indexes to respective mutually orthogonal polarized light waves input from the first port waveguide, thereby separating the mutually orthogonal polarized light waves, and that enables the separated mutually orthogonal polarized light waves to be output from the respective two second port waveguides.

Many embodiments in accordance with the invention are directed towards waveguides implementing birefringence control. In some embodiments, the waveguide includes a birefringent grating layer and a birefringence control layer. In further embodiments, the birefringence control layer is compact and efficient. Such structures can be utilized for various applications, including but not limited to: compensating for polarization related losses in holographic waveguides; providing three-dimensional LC director alignment in waveguides based on Bragg gratings; and spatially varying angular/spectral bandwidth for homogenizing the output from a waveguide. In some embodiments, a polarization-maintaining, wide-angle, and high-reflection waveguide cladding with polarization compensation is implemented for grating birefringence. In several embodiments, a thin polarization control layer is implemented for providing either quarter wave or half wave retardation.

Many embodiments in accordance with the invention are directed towards waveguides implementing birefringence control. In some embodiments, the waveguide includes a birefringent grating layer and a birefringence control layer. In further embodiments, the birefringence control layer is compact and efficient. Such structures can be utilized for various applications, including but not limited to: compensating for polarization related losses in holographic waveguides; providing three-dimensional LC director alignment in waveguides based on Bragg gratings; and spatially varying angular/spectral bandwidth for homogenizing the output from a waveguide. In some embodiments, a polarization-maintaining, wide-angle, and high-reflection waveguide cladding with polarization compensation is implemented for grating birefringence. In several embodiments, a thin polarization control layer is implemented for providing either quarter wave or half wave retardation.

An optical waveguide system and an electronic device are disclosed. The optical waveguide system comprises: a waveguide; an input coupler, coupling a light including a first and a second color component into the waveguide; and an output coupler, including: a first polarization color filter, converting the first color component of a first polarization state into the first color component of a second polarization state without changing the second color component of the first polarization state; a first polarization volume grating, coupling the first color component out of the waveguide; a second polarization color filter, converting the second color component of the first polarization state into the second color component of the second polarization state without changing the first color component of the first polarization state; a second polarization volume grating, coupling the second color component out of the waveguide.

An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first straight waveguide to receive incoming light and to output outgoing light to be coupled to a photodetector to provide an optical signal for rotational sensing. The gyroscope comprises a first microresonator ring proximate to the first straight waveguide. Light evanescently couples from the first straight waveguide to the first microresonator ring and experiences propagation loss while circulating as a guided beam within the first microresonator ring. The guided beam evanescently couples back from the first microresonator ring to the first straight waveguide to provide the optical signal for rotational sensing after optical gain is imparted to guided beam to counter the propagation loss. In a coupled-ring configurations, the first microresonator ring acts as a loss ring, and optical gain is imparted to a second microresonator ring which acts as a gain ring.

A polarization rotator structure includes: a first core structure formed at a first layer, extending from the first end to a second end, and a second core structure formed at a second layer that is at a different depth than the first layer and formed in proximity to the first core structure. The first core structure and the second core structure provide mode hybridization between at least two orthogonally polarized waveguide modes of the PRS. An optical splitter structure is optically coupled at a first end to the second end of the PRS, and optically coupled at a second end to at least two optical waveguides, and includes: a first core structure that is contiguous with at least one of the first or second core structures of the PRS, and a second core structure that is separate from both of the first and second core structures of the PRS.

A polarizing device includes: a first waveguide to guide input light, a second waveguide to guide TE-polarized light,
wherein the second waveguide includes a tapered input portion to polarization-selectively couple TE-polarized light from the first waveguide to the second waveguide, wherein the tapered input portion symmetrically overlaps the first waveguide, and the thickness of the tapered input portion has been selected to substantially prevent coupling of TM-polarized light from the first waveguide to the second waveguide, wherein the refractive index of the second waveguide is higher than the refractive index of the first waveguide.

The optical device can comprise a substrate having a first face opposite a second face, a thickness between the first face and the second face, the first face and the second face being planar, the first face being parallel the second face, the substrate being transparent to an electromagnetic radiation in a given spectrum; a planar polarization-dichroic focusing lens covering the first face, the lens having a first focusing power for a first polarization of the electromagnetic radiation and a second focusing power for a second polarization of the electromagnetic radiation, the second focusing power being different from the first focusing power; and a planar polarization-dichroic mirror covering the second face, the mirror being reflective to the first polarization and transparent to the second polarization.

A waveguide apparatus, comprises: disposed in at least one layer: an input coupler; a first fold grating; a second fold grating; an output coupler; and a source of light optically coupled to the waveguide providing at least first and second polarizations of the light and at least one wavelength. The input coupler is configured to cause the first polarization light to travel along a first total internal reflection (TIR) path and the second polarization light to travel along a second TIR path.

A polarization rotator structure includes: a first core structure formed at a first layer, extending from the first end to a second end, and a second core structure formed at a second layer that is at a different depth than the first layer and formed in proximity to the first core structure. The first core structure and the second core structure provide mode hybridization between at least two orthogonally polarized waveguide modes of the PRS. An optical splitter structure is optically coupled at a first end to the second end of the PRS, and optically coupled at a second end to at least two optical waveguides, and includes: a first core structure that is contiguous with at least one of the first or second core structures of the PRS, and a second core structure that is separate from both of the first and second core structures of the PRS.