Amplitude and phase control in distributed optical structures
View Patent ↗A distributed optical structure comprises a set of diffractive elements. Individual diffractive element transfer functions collectively yield an overall transfer function between entrance and exit ports. Diffractive elements are defined relative to virtual contours and include diffracting region(s) altered to diffract, reflect, and/or scatter incident optical fields (altered index, surface, etc). Element and/or overall set transfer functions (amplitude and/or phase) are determined by: longitudinal and/or angular displacement of diffracting region(s) relative to a virtual contour (facet-displacement grayscale); longitudinal displacement of diffractive elements relative to a virtual contour (element-displacement grayscale); and/or virtual contour(s) lacking a diffractive element (proportional-line-density gray scale). Optical elements may be configured: as planar or channel waveguides, with curvilinear diffracting segments; to support three-dimensional propagation with surface areal diffracting segments; as a diffraction grating, with grating groove or line segments.
1. An optical apparatus, comprising an optical element having an input optical port, an output optical port, and at least two diffractive element subsets, each subset having at least two diffracting regions, wherein
an input optical field emerging from the optical input port impinges on the diffractive element subsets,
each diffractive element subset diffracts, with a corresponding diffracted-field amplitude and a corresponding diffracted-field phase, at least a portion of the input optical field to the optical output port,
relative diffracted-field amplitude of corresponding diffracted portions of the input optical field diffracted by the diffractive element subsets is determined at least in part by correlated displacement of diffracting regions comprising the diffractive element subsets.
2. The apparatus of claim 1 , wherein
the optical element is a waveguide, the waveguide substantially confining in at least one transverse dimension optical fields propagating therein,
each of the diffractive element virtual contours is a curvilinear virtual contour, each of the diffracting regions being a curvilinear diffracting segment.
3. The apparatus of claim 2 , wherein the optical element is a channel waveguide, the channel waveguide substantially confining in two transverse dimensions optical fields propagating in one dimension therein.
4. The apparatus of claim 3 , wherein the channel waveguide is formed on a substrate.
5. The apparatus of claim 3 , wherein the channel waveguide comprises an optical fiber.
6. The apparatus of claim 2 , wherein the optical element is a planar waveguide, the planar waveguide substantially confining in one transverse dimension optical fields propagating in two dimensions therein.