Fabrication of high efficiency, high quality, large area diffractive waveplates and arrays

Abstract

The objective of the present invention is providing a method for fabricating high quality diffractive waveplates and their arrays that exhibit high diffraction efficiency over large area, the method being capable of inexpensive large volume production. The method uses a polarization converter for converting the polarization of generally non-monochromatic and partially coherent input light beam into a pattern of periodic spatial modulation at the output of said polarization converter. A substrate carrying a photoalignment layer is exposed to said polarization modulation pattern and is coated subsequently with a liquid crystalline material. The high quality diffractive waveplates of the present invention are obtained when the exposure time of said photoalignment layer exceeds by generally an order of magnitude the time period that would be sufficient for producing homogeneous orientation of liquid crystalline materials brought in contact with said photoalignment layer. Compared to holographic techniques, the method is robust with respect to mechanical noises, ambient conditions, and allows inexpensive production via printing while also allowing to double the spatial frequency of optical axis modulation of diffractive waveplates.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0001]This invention was made with Government support under Contract No. W911QY-07-C-0032.RIGHTS OF THE GOVERNMENT[0002]The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.CROSS REFERENCES[0003]Sh. D. Kakichashvili, “Method for phase polarization recording of holograms,” Soy. J. Quantum. Electron. 4, 795-798, 1974.[0004]T. Todorov, et al., High-sensitivity material with reversible photo-induced anisotropy, Opt. Commun., 47, 123-126, 1983.[0005]M. Attia, et al., “Anisotropic gratings recorded from two circularly polarized coherent waves,” Opt. Commun., 47, 85-90, 1983.[0006]G. Cipparrone, et. al, “Permanent polarization gratings in photosensitive langmuir blodget films,” Appl. Phys. Lett. 77, 2106-2108, 2000.[0007]L. Nikolova et al., “Diffraction efficiency and selectivity of polarization holographic reco...

AI Technical Summary

Benefits of technology

[0051]Thus, the objective of the present invention is providing means for fabricating high quality DWs in large area, typically exceeding 1″ in sizes, in large quantities, with high yield, and low cost.

Problems solved by technology

A critically important issue for producing LC orientation patterns at high spatial frequencies is their mechanical stability.

While acceptable for research and development purposes, none of the techniques known in the prior art can be used for fabricating high quality DWs and their arrays in large area, inexpensively, and in high volume production.

Thus, such a grating modulated polarization of the output light at macroscopic scales and could not be used for production of microscale-period gratings with diffractive properties at optical wavelengths.

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