Controllable planar optical focusing system

摘要

An optical device has a first metasurface disposed over a substrate. A high-contrast pattern of the first metasurface is operable for modifying, over a first phase profile, a phase front of an incident light beam. A second metasurface, is disposed over a plane parallel to the first metasurface with a second high-contrast pattern and operable for shaping, over a second phase profile, the modified phase front of the incident light beam into a converging spherical phase front. A spacer layer, in which the modified phase front of the incident light beam diffracts, is disposed in a controllably changeable separation between the first and second metasurfaces. Controllably changing the separation between the first and the second metasurfaces by a first distance correspondingly changes the position of the focus point of the converging spherical phase front by a second distance significantly greater than the first distance.

主权项

1. An optical device, comprising:
a substrate; a first metasurface disposed over the substrate, the first metasurface comprising a first high-contrast pattern operable for modifying, over a first phase profile, a phase front of a collimated narrow-band light beam incident to the first metasurface; a second metasurface disposed over a plane parallel to the first metasurface, the second metasurface comprising a second high-contrast pattern operable for shaping, over a second phase profile, the phase front of the modified phase front of the incident light beam into a converging spherical phase front; and a spacer layer in which the modified phase front of the incident light beam diffracts, the spacer layer disposed in a controllable separation between the first metasurface and the second surface, the separation relating to a position of a focus point of the converging spherical phase front beyond the second metasurface, in relation to the first metasurface in a direction of propagation of the incident light beam, wherein controllably changing the separation between the first metasurface and the second metasurface by a first distance correspondingly changes the position of the focus point of the converging spherical phase front by a second distance, wherein the second distance exceeds the first distance to a significant degree.