Monolithic polarizing diffractive structures and associated methods

Abstract

A monolithic polarizing diffractive structure includes a system having at least two parallel continuous planar surfaces, a diffractive pattern on one of the at least two parallel continuous surfaces, the diffractive pattern including at least two diffractive elements integral with the one of the at least two continuous surfaces, the at least two diffractive elements defining a monolithic diffractive pattern, and a polarizing pattern on one of the at least two parallel continuous surfaces. The polarizing pattern includes at least two polarizing elements, each polarizing element corresponding to a respective diffractive element, the at least two polarizing elements outputting polarizations rotated with respect to one another, the at least two polarizing elements defining a monolithic polarizing pattern.

1 - 28 . (canceled) 
     
     
         29 . A monolithic polarizing diffractive structure, comprising:
 a system having at least two parallel continuous planar surfaces:   a diffractive pattern on one of the at least two parallel continuous surfaces, the diffractive pattern including at least two diffractive elements integral with the one of the at least two continuous surfaces, the at least two diffractive elements defining a monolithic diffractive pattern; and   a polarizing pattern on one of the at least two parallel continuous surfaces, the polarizing pattern including at least two polarizing elements, each polarizing element corresponding to a respective diffractive element, the at least two polarizing elements outputting polarizations rotated with respect to one another, the at least two polarizing elements defining a monolithic polarizing pattern.   
     
     
         30 . The monolithic polarizing diffractive structure as claimed in  claim 29 , wherein the system comprises a substrate on which the monolithic polarizing pattern is formed. 
     
     
         31 . The monolithic polarizing diffractive structure as claimed in  claim 30 , wherein the monolithic polarizing pattern comprises a subwavelength structure. 
     
     
         32 . The monolithic polarizing diffractive structure as claimed in  claim 30 , wherein an etch depth d is determined by the equation:
     d=λ /2 Δn      
       where λ is a wavelength at which the diffractive element is to be used and Δn is a difference between refractive indices of the substrate for orthogonal polarization states of the monolithic polarizing pattern. 
     
     
         33 . The monolithic polarizing diffractive structure as claimed in  claim 32 , wherein a period of the monolithic polarizing pattern is selected to maximize Δn. 
     
     
         34 . The monolithic polarizing diffractive structure as claimed in  claim 30 , wherein the substrate is birefringent. 
     
     
         35 . The monolithic polarizing diffractive structure as claimed in  claim 34 , wherein the monolithic polarizing pattern is etched into a surface of the substrate, the monolithic polarizing pattern having an etch depth determined in accordance with a difference between an ordinary refractive index and an extraordinary refractive index of the substrate. 
     
     
         36 . The monolithic polarizing diffractive structure as claimed in  claim 35 , wherein a period of the monolithic polarizing pattern is selected to equal a size of one of the at least two diffractive elements. 
     
     
         37 . The monolithic polarizing diffractive structure as claimed in  claim 30 , wherein a first surface of the substrate serves as the one of the at least two continuous surfaces with which the diffractive elements are integral. 
     
     
         38 . The monolithic polarizing diffractive structure as claimed in  claim 37 , wherein the monolithic polarizing pattern and the diffractive element are integral with the first surface of the substrate. 
     
     
         39 . The monolithic polarizing diffractive structure as claimed in  claim 37 , wherein the monolithic polarizing pattern is integral with a second surface, different from the first surface, of the substrate. 
     
     
         40 . The monolithic polarizing diffractive structure as claimed in  claim 29 , wherein at least one of the at least two polarizing elements is featureless. 
     
     
         41 . The monolithic polarizing diffractive structure as claimed in  claim 29 , wherein the polarizations of the at least two polarizing elements are rotated by 90° with respect to one another. 
     
     
         42 . The monolithic polarizing diffractive structure as claimed in  claim 29 , wherein the monolithic diffractive pattern comprises an alternating array of x dipoles and y dipoles. 
     
     
         43 . A method of making a monolithic polarizing diffractive structure, the method comprising:
 creating a diffractive design having at least two diffractive elements;   creating a polarizing pattern having at least two polarizing elements, the at least two polarizing elements outputting polarizations rotated with respect to one another;   transferring the diffractive design to a surface of a system having at least two continuous surfaces to form a diffractive pattern having at least two diffractive elements integral with one of the at least two continuous surfaces, the at least two diffractive elements defining a monolithic diffractive pattern; and   transferring the polarizing pattern to one of the at least two continuous surfaces, each of the at least two polarizing elements corresponding to a respective one of the at least two diffractive elements, the at least two controlled polarizing elements defining a monolithic polarizing pattern.   
     
     
         44 . The method as claimed in  claim 43 , wherein transferring the monolithic polarizing pattern includes etching a substrate of the system to an etch depth d determined by the equation:
     d λ/2 Δn  
   where λ is a wavelength at which the diffractive structure is to be used and Δn is a different between refractive indices of the substrate for orthogonal polarization states of the monolithic polarizing pattern.   
     
     
         45 . The method as claimed in  claim 44 , further comprising selecting a period of the monolithic polarizing pattern to maximize Δn. 
     
     
         46 . The method as claimed in  claim 43 , wherein transferring the monolithic polarizing pattern includes etching a birefringent substrate to an etch depth determined in accordance with a difference between an ordinary refractive index and an extraordinary refractive index of the birefringent substrate. 
     
     
         47 . The method as claimed in  claim 46 , wherein a period of the polarizing elements is selected to equal a size of one of the at least two diffractive elements. 
     
     
         48 . The method as claimed in  claim 43 , wherein the at least two surfaces are on a substrate. 
     
     
         49 . The method as claimed in  claim 48 , wherein transferring the polarizing elements and the diffractive elements occur on a same side of the substrate. 
     
     
         50 . The method as claimed in  claim 48 , wherein transferring the polarizing elements and the diffractive elements occur on different sides of the substrate. 
     
     
         51 . The method as claimed in  claim 48 , wherein transferring the monolithic polarizing pattern occurs before transferring the diffractive design.