Abstract: Techniques for fabricating a slanted structure are disclosed. In one embodiment, a method of fabricating a slanted surface-relief structure in a material layer includes forming a thin hard mask on top of an intermediate mask layer, etching the intermediate mask layer at a slant angle using the thin hard mask to form a slanted intermediate mask, and etching the material layer at the slant angle using the slanted intermediate mask to form the slanted surface-relief structure in the material layer. The intermediate mask layer is characterized by an etch rate greater than an etch rate of the material layer.

Abstract: A surface-relief grating includes a base surface-relief grating comprising a plurality of ridges that include a first material, and a second material on only a top surface or a single sidewall of each ridge of the plurality of ridges, where the second material is different from the first material. A method of fabricating the surface-relief grating includes etching or molding a base surface-relief grating that includes a plurality of ridges, depositing a material layer on the plurality of ridges, and selectively etching the material layer to increase a height or a slant angle of an edge of a ridge in the plurality of ridges to make the surface-relief grating that includes the base surface-relief grating.

Abstract: A method is described for modifying the mechanical properties of NIL materials. The method includes applying an imprint mask to a nano-imprint lithography (NIL) material layer to create an imprinted NIL material layer, with the NIL material layer comprised of a NIL material. The method further includes detaching the imprinted NIL material layer from the imprint mask, with the modulus level of the NIL material below a flexibility threshold to cause a shape of the imprinted NIL material layer to remain unchanged after detachment. The modulus level of the NIL material of the imprinted NIL material layer is increased beyond a strength threshold to create a first imprint layer, with the imprint layer having a structure that remains unaffected by a subsequent process to form a second imprint layer matching a master mold pattern.

Abstract: A method is described for creating a modified mask with low surface energies for a nano-imprint lithography (NIL) imprinting process. The method includes applying a master mold to an imprint mask material to create an imprint mask. The method further includes modifying the imprint mask by applying a treatment to the imprint mask to cause a surface energy level of the imprint mask to fall below a sticking threshold. The modified imprint mask is applied to a nano-imprint lithography (NIL) material to create an imprinted NIL material layer. The surface energy level of the imprint mask causes a shape of the imprinted NIL material layer to be remain unchanged when the imprinted NIL material layer is detached from the modified imprint mask.

Abstract: A surface-relief structure and techniques for fabricating the surface-relief structure are disclosed. The surface-relief structure includes a substrate, a plurality of ridges on the substrate, and a plurality of grooves each between two adjacent ridges. The plurality of ridges are slanted with respect to the substrate, and include a material having a refractive index at least 2.3. Regions of the substrate at bottoms of the plurality of grooves include at least one of hydrogen or nitrogen at a concentration of at least 1010/cm3.

Abstract: A method of fabricating a slanted surface-relief structure in a material layer using a chemically assisted reactive ion beam etching (CARIBE) system includes generating, by a reactive ion source generator of the CARIBE system using a first reactive gas, a plasma including reactive ions of the first reactive gas that are configured to react with the material layer to generate volatile materials; extracting and accelerating, by one or more grids of the CARIBE system, at least some of the reactive ions in the plasma to form a reactive ion beam towards the material layer; and injecting, by a gas ring of the CARIBE system, a second reactive gas onto the material layer, the second reactive gas configured to react with the material layer. The reactive ion beam and the second reactive gas etch the material layer both physically and chemically to form the slanted surface-relief structure in the material layer.

Abstract: A manufacturing system performs a deposition of an etch-compatible film over a substrate. The etch-compatible film includes a first surface and a second surface opposite to the first surface. The manufacturing system performs a partial removal of the etch-compatible film to create a surface profile on the first surface with a plurality of etch heights relative to the substrate. The manufacturing system performs a lithographic patterning of a photoresist deposited over the created profile in the etch-compatible film to obtain the plurality of etch heights and one or more duty cycles corresponding to the etch-compatible film deposited over the substrate.

Abstract: A surface-relief structure and techniques for fabricating the surface-relief structure are disclosed. The surface-relief structure includes a substrate, a plurality of ridges on the substrate, and a plurality of grooves each between two adjacent ridges. The plurality of ridges are slanted with respect to the substrate, and include a material having a refractive index at least 2.3. Regions of the substrate at bottoms of the plurality of grooves include at least one of hydrogen or nitrogen at a concentration of at least 1010/cm3.

Abstract: A pupil replication waveguide for a projector display includes a slab of transparent material for propagating display light in the slab via total internal reflection. A diffraction grating is supported by the slab. The diffraction grating includes a plurality of tapered slanted fringes in a substrate for out-coupling the display light from the slab by diffraction into a blazed diffraction order. A greater portion of the display light is out-coupled into the blazed diffraction order, and a smaller portion of the display light is out-coupled into a non-blazed diffraction order. The tapered fringes result in the duty cycle of the diffraction grating varying along the thickness direction of the diffraction grating, to facilitate suppressing the portion of the display light out-coupled into the non-blazed diffraction order.

Abstract: A method is described for creating a modified mask with low surface energies for a nano-imprint lithography (NIL) imprinting process. The method includes applying a master mold to an imprint mask material to create an imprint mask. The method further includes modifying the imprint mask by applying a treatment to the imprint mask to cause a surface energy level of the imprint mask to fall below a sticking threshold. The modified imprint mask is applied to a nano-imprint lithography (NIL) material to create an imprinted NIL material layer. The surface energy level of the imprint mask causes a shape of the imprinted NIL material layer to be remain unchanged when the imprinted NIL material layer is detached from the modified imprint mask.

Abstract: Techniques for fabricating a slanted structure are disclosed. In one embodiment, a method of fabricating a slanted surface-relief structure in a material layer includes forming a thin hard mask on top of an intermediate mask layer, etching the intermediate mask layer at a slant angle using the thin hard mask to form a slanted intermediate mask, and etching the material layer at the slant angle using the slanted intermediate mask to form the slanted surface-relief structure in the material layer. The intermediate mask layer is characterized by an etch rate greater than an etch rate of the material layer.

Abstract: Techniques for fabricating a slanted structure are disclosed. In one embodiment, a method for fabricating a slanted structure on a material layer includes forming a mask layer on the material layer, and implanting ions into a plurality of regions of the material layer at a slant angle greater than zero using an ion beam and the mask layer. The slant angle is measured with respect to a surface normal of the material layer. Implanting the ions into the plurality of regions of the material layer changes a refractive index or an etch rate of the plurality of regions of the material layer. In some embodiments, the method further includes wet-etching the material layer using an etchant to remove materials in the plurality of regions of the material layer. In some embodiments, the method includes either simultaneous or post-implantation etching of modified material through a dry etching process using reactive etchants in feed gas.

Abstract: A manufacturing system for fabricating self-aligned grating elements with a variable refractive index includes a patterning system, a deposition system, and an etching system. The manufacturing system performs a lithographic patterning of one or more photoresists to create a stack over a substrate. The manufacturing system performs a conformal deposition of a protective coating on the stack. The manufacturing system performs a deposition of a first photoresist of a first refractive index on the protective coating. The manufacturing system performs a removal of the first photoresist to achieve a threshold value of first thickness. The manufacturing system performs a deposition of a second photoresist of a second refractive index on the first photoresist. The second refractive index is greater than the first refractive index. The manufacturing system performs a removal of the second photoresist to achieve a threshold value of second thickness to form a portion of an optical grating.

Abstract: A pupil replication waveguide for a projector display includes a slab of transparent material for propagating display light in the slab via total internal reflection. A diffraction grating is supported by the slab. The diffraction grating includes a plurality of tapered slanted fringes in a substrate for out-coupling the display light from the slab by diffraction into a blazed diffraction order. A greater portion of the display light is out-coupled into the blazed diffraction order, and a smaller portion of the display light is out-coupled into a non-blazed diffraction order. The tapered fringes result in the duty cycle of the diffraction grating varying along the thickness direction of the diffraction grating, to facilitate suppressing the portion of the display light out-coupled into the non-blazed diffraction order.

Abstract: A manufacturing system for fabricating self-aligned grating elements with a variable refractive index includes a patterning system, a deposition system, and an etching system. The manufacturing system performs a lithographic patterning of one or more photoresists to create a stack over a substrate. The manufacturing system performs a conformal deposition of a protective coating on the stack. The manufacturing system performs a deposition of a first photoresist of a first refractive index on the protective coating. The manufacturing system performs a removal of the first photoresist to achieve a threshold value of first thickness. The manufacturing system performs a deposition of a second photoresist of a second refractive index on the first photoresist. The second refractive index is greater than the first refractive index. The manufacturing system performs a removal of the second photoresist to achieve a threshold value of second thickness to form a portion of an optical grating.

Abstract: Disclosed herein are techniques for fabricating straight or slanted variable-etch-depth gratings. A photoresist material for fabricating a variable-etch-depth grating in a substrate is sensitive to light with a wavelength shorter than 300 nm and has an etch rate comparable to the etch rate of the substrate. A depth of an exposed portion of a photoresist material layer including the photoresist material correlates with the exposure dose. After exposure using a gray-scale mask and development, the photoresist material layer has a non-uniform thickness. The photoresist material layer with the non-uniform thickness and the underlying substrate are etched using a straight etching or slanted etching process to form the straight or slanted variable-etch-depth grating in the substrate. The variable-etch-depth grating is characterized by a non-uniform depth profile corresponding to the non-uniform thickness of the photoresist material layer before etching.

Abstract: A pupil replication waveguide for a projector display includes a slab of transparent material for propagating display light in the slab via total internal reflection. A diffraction grating is supported by the slab. The diffraction grating includes a plurality of tapered slanted fringes in a substrate for out-coupling the display light from the slab by diffraction into a blazed diffraction order. A greater portion of the display light is out-coupled into the blazed diffraction order, and a smaller portion of the display light is out-coupled into a non-blazed diffraction order. The tapered fringes result in the duty cycle of the diffraction grating varying along the thickness direction of the diffraction grating, to facilitate suppressing the portion of the display light out-coupled into the non-blazed diffraction order.

Abstract: Ion implantation is used to fabricate an optical device having a varying refractive index. The optical device can include a substrate with a material disposed on the substrate. A refractive index of the material is changed by ion implantation. The material can also be etched or imprinted. The optical device can be used in a virtual-reality system or augmented-reality system to provide angular selectivity from a display to a user's eye.

Abstract: A pupil replication waveguide for a projector display includes a slab of transparent material for propagating display light in the slab via total internal reflection. A diffraction grating is supported by the slab. The diffraction grating includes a plurality of slanted fringes in a substrate for out-coupling the display light from the slab by diffraction into a blazed diffraction order. A greater portion of the display light is out-coupled into the blazed diffraction order, and a smaller portion of the display light is out-coupled into a non-blazed diffraction order. A refractive index contrast profile of the diffraction grating along a thickness direction of the diffraction grating is symmetrical, and a refractive index contrast is larger at a middle than at both sides of the refractive index contrast profile, whereby the portion of the display light out-coupled into the non-blazed diffraction order is decreased.

Abstract: A three-dimensional diffraction grating is generated by selective deposition and/or selective etching. The three-dimensional diffraction grating includes a substrate and a plurality of structures located at different positions on the substrate. The structures have different materials. Edges of at least some of the structures are aligned. The three-dimensional diffraction grating includes different materials and aligned edges in all three dimensions. With the different materials and aligned edges, the three-dimensional diffraction gratings is configured to eliminate display artifacts, such as ghost, rainbow, etc.