An augmented reality device includes a projector, projector optics optically coupled to the projector, and a substrate structure including a substrate having an incident surface and an opposing exit surface and a first variable thickness film coupled to the incident surface. The substrate structure can also include a first combined pupil expander coupled to the first variable thickness film, a second variable thickness film coupled to the opposing exit surface, an incoupling grating coupled to the opposing exit surface, and a second combined pupil expander coupled to the opposing exit surface.

A plurality of waveguide display substrates, each waveguide display substrate having a cylindrical portion having a diameter and a planar surface, a curved portion opposite the planar surface defining a nonlinear change in thickness across the substrate and having a maximum height D with respect to the cylindrical portion, and a wedge portion between the cylindrical portion and the curved portion defining a linear change in thickness across the substrate and having a maximum height W with respect to the cylindrical portion. A target maximum height D.sub.t of the curved portion is 10.sup.7 to 10.sup.6 times the diameter, D is between about 70% and about 130% of D.sub.t, and W is less than about 30% of D.sub.t.

A semiconductor-on-insulator (SOI) structure and a method for forming the SOI structure. The method includes forming a first dielectric layer on a first semiconductor layer. A second semiconductor layer is formed over an etch stop layer. A cleaning solution is provided to a first surface of the first dielectric layer. The first dielectric layer is bonded under the second semiconductor layer in an environment having a substantially low pressure. An index guiding layer may be formed over the second semiconductor layer. A third semiconductor layer is formed over the second semiconductor layer. A distance between a top of the third semiconductor layer and a bottom of the second semiconductor layer varies between a maximum distance and a minimum distance. A planarization process is performed on the third semiconductor layer to reduce the maximum distance.

A method includes providing a sacrificial wafer, contacting the sacrificial wafer to a photonic device wafer, and bonding the sacrificial wafer to the photonic device wafer. The sacrificial wafer includes a substrate and an electro-optical material strip disposed within a dielectric matrix. The photonic device wafer includes a photonic device die, and the electro-optical material strip is disposed proximate to the photonic device die. A photonic device structure includes a photonic device wafer and a sacrificial wafer. The photonic device structure includes a device wafer substrate and a photonic device die fabricated in a device wafer dielectric layer. The sacrificial wafer includes a sacrificial wafer substrate and an electro-optical material strip embedded in a sacrificial wafer dielectric matrix. The sacrificial wafer dielectric matrix is bonded to the device wafer dielectric layer, and the electro-optical material strip is disposed proximate to the photonic device die.

Disclosed herein are configurations and methods to produce very low loss waveguide structures, which can be single-layer or multi-layer. These waveguide structures can be used as a sensing component of a small-footprint integrated optical gyroscope. By using pure fused silica substrates as both top and bottom cladding around a SiN waveguide core, the propagation loss can be well below 0.1 db/meter. Low-loss waveguide-based gyro coils may be patterned in the shape of a spiral (circular or rectangular or any other shape), that may be distributed among one or more of vertical planes to increase the length of the optical path while avoiding the increased loss caused by intersecting waveguides in the state-of-the-art designs. Low-loss adiabatic tapers may be used for a coil formed in a single layer where an output waveguide crosses the turns of the spiraling coil.

A waveguide has a first and second portions, and a transitional portion with a first end joining the first portion and a second end joining the second portion. The first portion has a first thickness that is smaller than a second thickness of the second portion. The transitional portion has a thickness that gradually increases from the first thickness at its first end to the second thickness at its second end. In a fabrication method employing chemical-mechanical polishing (CMP), first and second CMP control structures are disposed on opposite sides of the waveguide. Spaces between the waveguide and the CMP control structures are filled with cladding material. CMP is performed to reduce a thickness of the waveguide. The CMP control structures control the CMP of the waveguide to form the transitional portion of the waveguide having the gradually increasing thickness.

An augmented reality device includes a projector, projector optics optically coupled to the projector, and an eyepiece optically coupled to the projector optics. The eyepiece includes an eyepiece waveguide characterized by lateral dimensions and an optical path length difference as a function of one or more of the lateral dimensions.

A semiconductor-on-insulator (SOI) structure and a method for forming the SOI structure. The method includes forming a first dielectric layer on a first semiconductor layer. A second semiconductor layer is formed over an etch stop layer. A cleaning solution is provided to a first surface of the first dielectric layer. The first dielectric layer is bonded under the second semiconductor layer in an environment having a substantially low pressure. An index guiding layer may be formed over the second semiconductor layer. A third semiconductor layer is formed over the second semiconductor layer. A distance between a top of the third semiconductor layer and a bottom of the second semiconductor layer varies between a maximum distance and a minimum distance. A planarization process is performed on the third semiconductor layer to reduce the maximum distance.

The present invention relates to a preparation method of multi-layer stacked waveguide. The method involves a preliminary step: providing an optical waveguide block, wherein the optical waveguide block has a substrate and a plurality of optical waveguides, the optical waveguides are disposed within the substrate and adjacent to an upper surface of the substrate; and a bonding step: flipping over another optical waveguide block and bonding it above the optical waveguide block to form a double-layer stacked waveguide structure. In this way, a multi-layer waveguide stack structure can be formed by directly stacking optical waveguide blocks directly provided with a plurality of optical waveguides. Multi-layer stacking only needs to be completed by heating, thinning and/or depositing a silicon oxide layer, saving manufacturing time and cost.

A plurality of waveguide display substrates, each waveguide display substrate having a cylindrical portion having a diameter and a planar surface, a curved portion opposite the planar surface defining a nonlinear change in thickness across the substrate and having a maximum height D with respect to the cylindrical portion, and a wedge portion between the cylindrical portion and the curved portion defining a linear change in thickness across the substrate and having a maximum height W with respect to the cylindrical portion. A target maximum height D.sub.t of the curved portion is 10.sup.7 to 10.sup.6 times the diameter, D is between about 70% and about 130% of D.sub.t, and W is less than about 30% of D.sub.t.