Optical apparatus

An optical apparatus, comprising:

• a plurality of optically switchable elements, each optically switchable element comprising a portion of phase change material defining a pixel of the apparatus, each pixel of phase change material being individually addressable to thermally switch between a plurality of stable states having different refractive indices relative to each other;
• a plurality of switching elements, each switching element corresponding to a different one of the pixels of phase change material and configured selectively to cause heating in a corresponding one of the pixels of phase change material to perform selective thermal switching of the pixel of phase change material independently of other pixels in the apparatus, wherein each pixel of phase change material has a length to width aspect ratio of at least 20:1;
• a first support substrate supporting the plurality of pixels of phase change material on a front face of the first support substrate;
• and
• a plurality of selector elements, each selector element comprising an electronic unit configured to provide a current to a corresponding one of the switching elements when the selector element is addressed by a control signal, wherein:
• the electronic unit of each selector element is positioned on the first support substrate outside of a viewing area of the apparatus, on the first support substrate on a surface other than the front face of the first support substrate, or on a second support substrate that is non-integral with the first support substrate.

An optical apparatus, comprising:

• a plurality of optically switchable elements, each optically switchable element comprising a portion of phase change material defining a pixel of the apparatus, each pixel of phase change material being individually addressable to thermally switch between a plurality of stable states having different refractive indices relative to each other;
• and
• a plurality of switching elements, each switching element corresponding to a different one of the pixels of phase change material and configured selectively to cause heating in a corresponding one of the pixels of phase change material to perform selective thermal switching of the pixel of phase change material independently of other pixels in the apparatus,
• wherein each pixel of phase change material has a length to width aspect ratio of at least 20:1, and
• wherein each optically switchable element comprises a stack of layers comprising a spacer layer provided between the pixel of phase change material and a support substrate, wherein the spacer layer consists of a single layer or comprises multiple layers of materials having different refractive indices.

An optical apparatus, comprising:

• a plurality of optically switchable elements, each optically switchable element comprising a portion of phase change material defining a pixel of the apparatus, each pixel of phase change material being individually addressable to thermally switch between a plurality of stable states having different refractive indices relative to each other;
• and
• a plurality of switching elements, each switching element corresponding to a different one of the pixels of phase change material and configured selectively to cause heating in a corresponding one of the pixels of phase change material to perform selective thermal switching of the pixel of phase change material independently of other pixels in the apparatus,
• wherein each pixel of phase change material has a length to width aspect ratio of at least 20:1, and
• wherein each optically switchable element comprises a stack of layers comprising a capping layer, wherein the pixel of phase change material is provided between the capping layer and a support substrate and the capping layer consists of a single layer or comprises multiple layers of materials having different refractive indices.