Phase-transforming optical reflector formed by partial etching or by partial etching with reflow
First Claim
1. An optical element comprising a reflective surface supported by a substantially solid substrate, the reflective surface comprising a multitude of discrete recessed and non-recessed areas arranged contiguously along the reflective surface, wherein:
- (a) the recessed or non-recessed areas include a non-empty subset of areas of the multitude having a largest transverse dimension less than about a design vacuum wavelength λ
0, and the recessed and non-recessed areas are characterized by a depth function d(x,y), as a function of two-dimensional position coordinates x and y along the reflective surface, that equals zero in the non-recessed areas and that assumes non-zero values in the recessed areas up to a maximum depth DR;
(b) the reflective surface is reflective over an operational wavelength range that includes the design vacuum wavelength λ
0, and a corresponding volume within each recessed area is substantially transparent over the operational wavelength range and is characterized by a first bulk refractive index n1(λ
);
(c) the optical element is structurally arranged so as to receive an optical signal incident on the reflective surface and to reflect at least a portion of the incident optical signal transformed substantially according to a specified effective phase transformation function φ
eff(x,y) that varies as a function of x and y; and
(d) the discrete areas of the multitude are variously sized and distributed on the reflective surface so as to impart on the reflected portion of the incident optical signal the effective phase transformation φ
eff(x,y).
5 Assignments
0 Petitions
Accused Products
Abstract
A reflective optical element includes a reflective surface comprising a multitude of discrete recessed and non-recessed areas arranged along the reflective surface. The discrete areas are arranged to approximate a desired phase function (typically modulo 2π) and are smaller than an operational wavelength in order to provide a range of phase delays needed to adequately approximate the desired phase function. Effecting at least partial reflow of one or more optical media or reflective materials can smooth the morphology of the reflective surface so as to reduce unwanted diffraction or scattering.
-
Citations
41 Claims
-
1. An optical element comprising a reflective surface supported by a substantially solid substrate, the reflective surface comprising a multitude of discrete recessed and non-recessed areas arranged contiguously along the reflective surface, wherein:
-
(a) the recessed or non-recessed areas include a non-empty subset of areas of the multitude having a largest transverse dimension less than about a design vacuum wavelength λ
0, and the recessed and non-recessed areas are characterized by a depth function d(x,y), as a function of two-dimensional position coordinates x and y along the reflective surface, that equals zero in the non-recessed areas and that assumes non-zero values in the recessed areas up to a maximum depth DR;(b) the reflective surface is reflective over an operational wavelength range that includes the design vacuum wavelength λ
0, and a corresponding volume within each recessed area is substantially transparent over the operational wavelength range and is characterized by a first bulk refractive index n1(λ
);(c) the optical element is structurally arranged so as to receive an optical signal incident on the reflective surface and to reflect at least a portion of the incident optical signal transformed substantially according to a specified effective phase transformation function φ
eff(x,y) that varies as a function of x and y; and(d) the discrete areas of the multitude are variously sized and distributed on the reflective surface so as to impart on the reflected portion of the incident optical signal the effective phase transformation φ
eff(x,y). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
-
Specification