Abstract: Techniques for an optical filter having robust crystallized nano-porous layers are disclosed herein. According to at least one embodiment, the optical filter includes a light-transmitting substrate and an optical coating. The optical coating is deposited on the light-transmitting substrate. The optical coating includes at least one crystallized nano-feature layer. The at least one crystallized nano-feature layer is deposited using high temperature oblique angle deposition and has a refractive index lower than a refractive index of the light-transmitting substrate.

Abstract: At least one embodiment in the disclosure describes a high efficiency directional light engine. The light engine comprises a light emitter emitting light and a collimation lens. The collimation lens has a cone-shaped sidewall, a base surface and a curved top surface. The height of the cone-shaped sidewall is at least three times more than the diameter of the base surface. The light emitter is optically coupled to and disposed in close proximity to the base surface. One or more first reflection images of the light emitter result from first reflection of the light off a surface of the cone-shaped sidewall. The diameter of the light emitter is substantially close to the diameter of the base surface so that the light emitter and the first reflection images form a virtual point light source with minimal gap(s) or without any gap between the light emitter and the first reflection images.

Abstract: At least one embodiment in the disclosure describes a high efficiency directional light engine. The light engine comprises a light emitter emitting light and a cone-shaped mirror having a base opening. The light emitter is disposed near or at the base opening. Light emitted from the light emitter is reflected off the cone-shaped mirror and results in one or more first reflection images. The light emitter occupies a substantial portion of the base opening such that the light emitter and the first reflection images forms a virtual point light source without a significant gap(s) between the light emitter and the first reflection images.

Abstract: There is herein described an optical filter. The optical filter includes a substrate and a plurality of at least four optical thin film layers. The optical thin film layers are disposed on top of the substrate. Each of the optical thin film layers has an effective refractive index different from effective refractive indices of the immediate upper and lower optical thin film layers. At least one of the optical thin film layers is a thickness tunable nano-feature layer. The nano-feature layer contains a plurality of flexible nano-features. At least one of the optical thin film layers is a dense layer.