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.

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.

Structures for a polarizer and methods of forming a structure for a polarizer. A first slotted waveguide component is positioned over a first waveguide core, and a second slotted waveguide component positioned over the first slotted waveguide component. The first slotted waveguide component includes a second waveguide core and a third waveguide core separated by a first slot, and the second slotted waveguide component includes a fourth waveguide core and a fifth waveguide core separated by a second slot. The first waveguide core is laterally aligned with the first slot and the second slot.

A high isolation optical splitter for the field of optical communications may include an integrated structure of an input fiber, a first output fiber, an input splitting/combining device, a first output splitting/combining device, an input rotation device, a first output rotation device, a first lens, an isolator core, a second lens, a second output rotation device, a second output splitting/combining device, and a second output fiber. By adopting the integrated structure, this disclosed splitter integrates functions of an optical isolator and an optical splitter, which both can input an optical signal into one input fiber and can distribute to two output optical fibers for output. The disclosed splitter can isolate light in opposite directions and can reduce damage to a light source at an input end. In a system application, the disclosed splitter can replace two conventional independent optical isolators and optical splitters to effectively reduce the assembly space, lower the assembly difficulty, simplify the assembly process, and facilitate the development of miniaturized and integrated applications of the system.

Example polarization splitter and rotator devices are described. In one example, an optical apparatus includes a splitter configured to split a light signal into a first signal having a first polarization and a second signal having a second polarization, a polarization rotator configured to rotate the second polarization of the second signal into a third polarization, and a polarization mode converter configured to convert the third polarization of the second signal into the first polarization. In certain aspects of the embodiments, the splitter can be a curved multi-mode inference (MMI) polarization splitter, and the polarization rotator comprises input and output ports, with the output port being wider than the input port. The polarization mode converter can be an asymmetrical waveguide taper mode converter. The devices described herein can overcome the deficiencies of conventional devices and provide low insertion loss, flat and/or wide wavelength response, high fabrication tolerance, and compact size.

Example polarization splitter and rotator devices are described. In one example, an optical apparatus includes a splitter configured to split a light signal into a first signal having a first polarization and a second signal having a second polarization, a polarization rotator configured to rotate the second polarization of the second signal into a third polarization, and a polarization mode converter configured to convert the third polarization of the second signal into the first polarization. In certain aspects of the embodiments, the splitter can be a curved multi-mode inference (MMI) polarization splitter, and the polarization rotator comprises input and output ports, with the output port being wider than the input port. The polarization mode converter can be an asymmetrical waveguide taper mode converter. The devices described herein can overcome the deficiencies of conventional devices and provide low insertion loss, flat and/or wide wavelength response, high fabrication tolerance, and compact size.

The present disclosure provides a polarization attenuator and a polarization attenuation method to solve the problem of polarization dependent loss of optical devices, or to be used in optical devices or systems as a polarizer structure. The polarization attenuator comprises a first main waveguide, an offset waveguide and a second main waveguide which are arranged in sequence, wherein an output surface of the first main waveguide partially overlaps an input surface of the offset waveguide; an output surface of the offset waveguide partially overlaps an input surface of the second main waveguide; the first main waveguide or the second main waveguide supports fundamental modes and supports at least one high order mode. Meanwhile, the present disclosure further provides the polarization attenuation method comprising following steps: 1) optical signals enter the first main waveguide; 2) the optical signals excite high order modes at a joint of the first main waveguide and the offset waveguide; and 3) the signals are mixed again at a joint of the second main waveguide and the offset waveguide, and power between a fundamental mode and high order modes of the offset waveguide is redistributed between the fundamental mode and the high order mode of the second main waveguide.

Optical polarization control devices that include two pairs of squeezing plates oriented in mutually perpendicular directions are described. Compressive forces exerted by the two pairs of plates onto an optical fiber can be configured for low polarization mode dispersion. Various methods and systems in which the polarization control devices can be employed are also described.

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.

Systems and embodiments for an integrated photonics mode splitter and converter are provided herein. In certain embodiments, a system includes a substrate having a first index of refraction. Additionally, the system includes a waveguide layer on the substrate, wherein the waveguide has a second index of refraction different from the first index of refraction. Also, the waveguide layer includes one or more mode splitters that receive at least one of a first photon in a first mode and a second photon in a second mode through an input port and provide one of the first photon through a first output port and the second photon through a second output port. The waveguide layer also includes a mode converter coupled to the second output of a mode splitter, wherein the mode converter receives the second photon through a port and outputs the second photon in the first mode through the port.