In an example, a photonic system includes a Si PIC with a Si substrate, a SiO.sub.2 box formed on the Si substrate, a first layer, and a second layer. The first layer is formed above the SiO.sub.2 box and includes a SiN waveguide with a coupler portion at a first end and a tapered end opposite the first end. The second layer is formed above the SiO.sub.2 box and vertically displaced above or below the first layer. The second layer includes a Si waveguide with a tapered end aligned in two orthogonal directions with the coupler portion of the SiN waveguide such that the tapered end of the Si waveguide overlaps in the two orthogonal directions and is parallel to the coupler portion of the SiN waveguide. The tapered end of the SiN waveguide is configured to be adiabatically coupled to a coupler portion of an interposer waveguide.

According to an example aspect, there is provided an apparatus comprising a first optical converter coupled to a fiber interface and to two waveguides, a dual rail encoder configured to encode dual rail form light from the two waveguides with payload information, and wherein the dual rail encoder is coupled to the first optical converter or to a second optical converter disposed between the dual rail encoder and the fiber interface, and wherein the first optical converter or the second optical converter is coupled so as to provide polarization encoded light into the fiber interface.

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.

Various examples are provided for tunable radio frequency (RF) filtering. In one example, a RF multiband filter includes a Lyot filter including a tunable birefringence loop including a circulator and a polarization controller (PC) and a phase modulator (PM). The Lyot filter can generate an optical comb based at least in part upon a received optical signal and a polarization rotation angle of the polarization controller. The phase modulator (PM) can generate a modulated tap signal by modulating the optical comb by a RF input signal.

A head-mounted light field display device, the device comprising at least one multiplexed light field display module adapted to face an eye of a viewer wearing the device, the multiplexed light field display module comprising a light field view image generator and a waveguide with a set of shutters, the light field view image generator operable to generate, over time, a set of beams of light from a different one of a set of light field view images, the shuttered waveguide operable to transmit the set of beams and to open, over time, a different subset of the set of shutters, the subset corresponding to a position associated with the view image, thereby to emit the set of beams via the subset, thereby to display to the viewer a time-varying optical light field representative of the set of view images.

This patent document discloses, among others, wavelength-selective switches (WSS) for redirecting optical WDM signals or channels based on a combination of spatially separating light in different optical polarizations in an optical birefringent material and using diffractive optics for separating light at different optical WDM wavelengths into spatially separated optical beam to perform wavelength-selective optical switching in optical WDM applications. Notably, the optics for processing the optical WDM signals in the disclosed optical WSS devices is designed to provide scalable optical WSS devices where different WDM signals share optical components to reduce designed optical components for different WDM signals.

An asymmetric adiabatic polarization beam splitter integrated with a waveband filtering splitter unit and a polarization filtering splitter unit is capable of being packaged to form an integrated optical waveguide filtering chip. The waveband filtering splitter unit utilizes an adiabatic optical waveguide structure and stimulated Raman adiabatic passage on an optical waveguide to split the energy of light sources of different bands to different spaces when the light energy is performed with an adiabatic process. The polarization filtering splitter unit utilizes the two orthogonal polarization modes of an optical waveguide with birefringence to achieve a polarization-dependent mode splitting effect based on an adiabatic theory. The asymmetric adiabatic polarization beam splitter realizes the characteristics of integration and high process tolerance, and improves the mass production feasibility.

Method for fabricating of all-optical-fiber based optical polarizer devoid of fusing of first and second optical fibers. The method includes a process of forming a substantially adiabatic optical fiber taper by pulling an optical fiber and interrupting this process when an optical power parameter measured at an output of the optical fiber is reduced below a pre-defined threshold as a result of said pulling. An optically-tapered single-mode polarization-maintaining optical fiber element fabricated according to the method and configured as such all-optical-fiber polarizer.

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 inventive circular chiral fiber polarizer is operable to convert linearly polarized light to circularly polarized light, may be advantageously fabricated in an in-fiber manner and to comprise desirable extinction ratio characteristics, and may also serve as an interface between a sequentially positioned polarization maintaining (PM) fiber, and a single mode (SM) fiber.