A bricked sub-wavelength periodic waveguide and a modal adapter, power divider and polarization splitter that use the waveguide. The waveguide includes blocks disposed periodically with a period “L.sub.z” on a substrate and which alternate with a covering material. The first blocks have a width “a.sub.x” and the second blocks have a width “b.sub.x”, alternating on the substrate according to a period “L.sub.x”, the second blocks being shifted a distance “d.sub.z” the first blocks in the direction of propagation. A modal adapter, a power divider and a polarization splitter all use the periodic waveguide and can operate with larger wave periods without leaving the sub-wavelength regime.

An apparatus of polarization self-compensated delay line interferometer. The apparatus includes a first waveguide arm of a first material of a first length disposed between an input coupler and an output coupler and a second waveguide arm of the first material of a second length different from the first length disposed between the same input coupler and the same output coupler. The apparatus produces an interference spectrum with multiple periodic passband peaks where certain TE (transverse electric) and TM (transverse magnetic) polarization mode passband peaks are lined up. The apparatus further includes a section of waveguide of a birefringence material of a third length added to the second waveguide arm to induce a phase shift of the lined-up TE/TM passband peaks to a designated grid as corresponding polarization compensated channels of a wide optical band.

A micro-ring resonator includes: at least one first straight waveguide; a second waveguide (Arm3) and a third waveguide (Arm2), where the second waveguide (Arm3) and the third waveguide (Arm2) form a closed annular waveguide, and the annular waveguide is coupled to the first waveguide; a fourth waveguide (Arm1), where the fourth waveguide (Arm1) is coupled to the annular waveguide; and a polarization splitter (PS), where one end of the polarization splitter (PS) is connected to the fourth waveguide (Arm1), and one end is connected to the second waveguide (Arm3) in the annular waveguide. In the micro-ring resonator, a distance between two waveguides for separately transmitting different polarized light breaks a limitation of a resonator radius, and further, a distance between a TE path and a TM path is reduced.

A polarization controller comprising: (i) an optical fiber, and (ii) a carrier surrounding the optical fiber, the carrier comprising an off-center through hole with at least one collapsed region, such that the optical fiber is situated within the through hole and contacts the at least one collapsed region of the through hole, and the collapsed region exerts pressure on the optical fiber.

Aspects of the present disclosure describe methods for reducing guided acoustic wave Brillouin (GAWBS) noise in an optical fiber that may be included in an optical communications system by reducing the polarization diffusion length of the fiber by increasing the birefringence of the optical fiber, the increased birefringence of the optical fiber being increased with respect to its average magnitude. Additionally, the polarization diffusion length is reduced by reducing the coherence length of birefringence of the optical fiber.

Systems and methods for an integrated photonics vertical coupler are provided herein. In certain embodiments, a device includes a first waveguide having a first photon and a second photon propagating therein, wherein the first photon and the second photon are propagating in orthogonal modes. Further, the device includes a second waveguide having a second coupling portion in close proximity with a first coupling portion of the first waveguide, wherein a physical relationship between the first waveguide and the second waveguide along the length of the second coupling portion causes an adiabatic transfer of the first photon and the second photon into distinct orthogonal modes of the second waveguide at different locations in the second coupling portion.

A polarization converter based on taking a high-order TE mode as a transition mode comprises a ridge waveguide (1) and a slab waveguide (2) that are arranged in double layers and varying in width, and a strip waveguide (4) which is varying in width. The ridge waveguide (1) is disposed on the upper end face of the slab waveguide (2), and is aligned with two ends of the slab waveguide (2). The right end of the ridge waveguide (1) and the slab waveguide (2) are connected with the strip waveguide (4) with the varying width. A TM.sub.0 mode enters from the left ends of the ridge waveguide and the slab waveguide, and is converted into a TE.sub.0 mode for output. On the contrary, the TE.sub.0 mode enters from the right end of the strip waveguide and is converted into the TM.sub.0 mode for output.

An optical waveguide device includes a pair of waveguides. One of the waveguides includes a first core formed in a conversion region and a third core formed in an exit region. The other of waveguides includes a second core formed in the conversion region and a fourth core formed in the exit region. Cross-sectional areas of the first and second cores are different from each other at an input end. Distributions of a refractive index of the first and second cores are respectively asymmetric in a perpendicular direction. A quantitative relation provided at the input end between an effective refractive index of an odd mode of TE0 and an effective refractive index of an even mode of TM0 is opposite to the quantitative relation provided at the output end. Cross-sectional areas of the third and fourth cores are different from each other at an output end.

The present application discloses a polarization beam splitter (PBS). The PBS includes a silicon substrate and a planar structure formed thereon characterized by an isosceles trapezoid shape with a first parallel side and a second parallel side connected by two tapered sides. The first parallel side has longer width than the second parallel side, both of which is separated by a length no greater than 100 μm along a line of symmetry bisecting the pair of parallel sides. The PBS further includes a pair of input ports coupled to the first parallel side and a pair of output ports coupled to the second parallel side. The planar structure is configured to receive an input light wave of any wavelength in C-band via one input port and split to a TE-mode light wave and a TM-mode light wave respectively outputting to the pair of output ports.

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.