A polarization volume grating (PVG) includes a bulk, birefringent medium characterized by a plurality of helical structures with helix axes and a periodicity Λ.sub.y and an anisotropic alignment material having a rotatable optical axis, disposed on a top or bottom surface of the medium. The PVG is characterized in that the optical axis of the alignment material has a continuously rotated optical axis orientation in a plane of the material surface and a periodicity Λ.sub.x, wherein the helix axes are normal to the optical axes in the alignment material surface, further wherein the birefringent medium is characterized by a plurality of controllably slanted refractive index planes having a slant angle φ=±arctan (Λ.sub.y/Λ.sub.x) and a Bragg period Λ.sub.B. Fabrication methods are disclosed.

A high resolution, wide spectral range, optical apparatus that includes an optical resonator cavity and a wavelength demultiplexer, arrangeable in multiple configurations. A method for increasing the resolution of a wavelength demultiplexer involves inputting light into an optical resonant cavity; inputting a plurality of different resonant output wavelengths to a wavelength demultiplexer; and routing each different resonant wavelength to a different output waveguide of the demultiplexer to generate a demultiplexer output spectrum. The method further involves performing either a time serialization or a space serialization procedure to increase the channel density and fully cover the spectrum of interest.

An optical assembly includes a first grating device configured to: receive a light beam that includes an optical signal with a particular wavelength from a fiber; and change a propagation direction of the optical signal according to the particular wavelength of the optical signal. The optical assembly also includes a second grating device configured to: receive the optical signal outputted from the first grating device; change the propagation direction of the optical signal according to the particular wavelength of the optical signal; and direct the optical signal onto a grating coupler. The first grating device and the second grating device are configured to satisfy a plurality of configuration constraints.

Aspects of embodiments pertain to beam combining devices for coherent and spectral beam-combining. The coherent beam combining (CBC) device may comprise a monolithic body having an input surface and an output surface. The input surface may be configured to direct a plurality of coherent entering optical beams through an optical pathway inside the monolithic body towards the output surface; and a phase mask configured for combining beams, exiting from the output surface of the monolithic body, to form a single combined output beam. The Spectral beam combining (SBC) device may include a monolithic body configured to direct the entering optical beams through a multi-diffraction optical pathway inside the monolithic body by directing the entering optical beams such as to impinge a diffractive surface thereof at least twice, for combining the entering optical beams into a single multispectral combined output optical beam. Embodiments may also include methods for cascaded beam combining, using multiple combining devices in a network configuration.

Configurations for a diffraction grating design that mitigates thermal wavelength shifts and corresponding methods thereof are disclosed. The wavelength stability monitoring system may include a planar waveguide that receives input light directed toward a diffraction grating. The diffraction grating may reflect the light back through the planar waveguide and to one or more detectors. The planar waveguide may include multiple materials, such as a first material and a second athermal material that is adjacent to the first material. The athermal material may mitigate thermal wavelength shifts of the light. The design of the athermal material may include targeting a ratio of the input and output path lengths across sets of input and output angles of light that pass through the first material and the second athermal material. In some examples, the output waveguides may be positioned to receive leakage modes of light.

Provided are a diffraction grating device, a method of manufacturing the diffraction grating device, and an optical apparatus including the diffraction grating device. The diffraction grating device includes a diffraction grating arranged on a light reflection substrate. The diffraction grating includes a plurality of diffraction elements, each diffraction element from among the plurality of diffraction elements having a height that causes a destructive interference between first light rays reflected by a top surface therefore and second light rays reflected by a bottom surface thereof, the first and second light rays being incident on the top and bottom surfaces, respectively, at an incidence angle greater than 45°.

Methods and systems concerning demultiplexing and multiplexing light in optical multiplexing systems are disclosed herein. An optical multiplexing system may include a number of light emitters and a number of associated waveguides. Light emitted from each of the number of light emitters may travel through the associated waveguide and may enter a multiplexer, where a multiplexing operation may occur. At least one of the number of light emitters may be configured to emit light with multiple wavelengths. Such a light emitter may further be associated with a demultiplexer to demultiplex the light with multiple wavelengths before the light reaches a multiplexer. After a demultiplexing operation, the demultiplexed light may be directed to multiple waveguides and the multiple waveguides may guide the demultiplexed light to a multiplexer.

Configurations for a tunable Echelle grating are disclosed. The tunable Echelle grating may include an output waveguide centered in a waveguide array, with input waveguides on both sides of the output waveguide. A metal tuning pad may be located over the slab waveguide and may be heated to induce a temperature change in the slab waveguide. By increasing the temperature of the propagation region of the slab waveguide, the index of refraction may shift, thus causing the peak wavelength of the channel to shift. This may result in an optical component capable of multiplexing multiple light sources in an energy efficient manner while maintaining a small form factor.

An on-chip optical switch based on an echelle grating and a phase tuning element is described herein. The phase tuning element may change a refractive index of the material through which an optical signal propagates, thereby causing a change in the angle of propagation of the optical signal. By dynamically tuning the phase change element, the refractive index change may be controlled such that the deviation of the optical signal causes the optical signal to be focused on a particular coupling waveguide out of an array of coupling waveguides. The echelle grating with the active phase change element form a configurable optical switch capable of switching an optical signal between two or more coupling waveguides, that may be respectively connected to different optical signal processing pathways.

An on-chip optical switch based on an echelle grating and a phase tuning element is described herein. The phase tuning element may change a refractive index of the material through which an optical signal propagates, thereby causing a change in the angle of propagation of the optical signal. By dynamically tuning the phase change element, the refractive index change may be controlled such that the deviation of the optical signal causes the optical signal to be focused on a particular coupling waveguide out of an array of coupling waveguides. The echelle grating with the active phase change element form a configurable optical switch capable of switching an optical signal between two or more coupling waveguides, that may be respectively connected to different optical signal processing pathways.