ACTIVE MODULATION OF THE REFRACTIVE INDEX IN ORGANIC THIN FILMS VIA CHARGE INJECTION

1 . A birefringent organic thin film comprising:

an organic solid crystalline phase having mutually orthogonal in-plane refractive indices (n x and n y ) and a through thickness refractive index (n z ), wherein n x >1.4, n y >1.4, n z >1.4, Dn xy ≥0.1, Dn xy >Dn xz , and Dn xy >Dn yz .

2 . The birefringent organic thin film of claim 1 , wherein Dn xz <0.01 and Dn yz <0.01.

3 . The birefringent organic thin film of claim 1 , wherein n x ≠n y ≠n z or n x ≠n y =n z .

4 . The birefringent organic thin film of claim 1 , wherein the organic solid crystalline phase comprises aligned molecules.

5 . The birefringent organic thin film of claim 1 , wherein the organic solid crystalline phase comprises a hydrocarbon compound selected from the group consisting of anthracene, phenanthrene, pyrene, corannulene, fluorene, and biphenyl.

6 . The birefringent organic thin film of claim 1 , wherein the organic solid crystalline phase comprises a heterocycle selected from the group consisting of furan, pyrrole, thiophene, pyridine, pyrimidine, and piperidine.

7 . The birefringent organic thin film of claim 1 , wherein the organic solid crystalline phase comprises a dopant selected from the group consisting of fluorine, chlorine, nitrogen, oxygen, sulfur, and phosphorus.

8 . The birefringent organic thin film of claim 1 , wherein the thin film comprises a single crystal.

9 . The birefringent organic thin film of claim 1 , wherein the thin film is substantially planar.

10 . The birefringent organic thin film of claim 1 , wherein the thin film is disposed between a primary electrode and a secondary electrode overlying at least a portion of the primary electrode.

11 . The birefringent organic thin film of claim 1 , wherein the thin film comprises a first refractive index along a chosen direction in a first biased state and a second refractive index along the chosen direction in a second biased state.

12 . A head-mounted display comprising the birefringent organic thin film of claim 1 .

13 . A method comprising:

forming a primary electrode structure;

forming an organic solid crystal layer over the primary electrode structure;

forming a secondary electrode structure over the organic solid crystal layer and overlapping at least a portion of the primary electrode structure;

applying a first voltage between the primary electrode structure and the secondary electrode structure to create a first refractive index within the organic solid crystal layer along a chosen direction; and

applying a second voltage between the primary electrode structure and the secondary electrode structure to create a second refractive index within the organic solid crystal layer along the chosen direction.

14 . The method of claim 13 , wherein the organic solid crystal layer comprises a hydrocarbon compound selected from the group consisting of anthracene, phenanthrene, pyrene, corannulene, fluorene, and biphenyl.

15 . The method of claim 13 , wherein forming the organic solid crystal layer comprises epitaxial crystal growth.

16 . The method of claim 13 , wherein the secondary electrode structure comprises a plurality of concentric ring electrodes.

17 . The method of claim 13 , wherein the organic solid crystal layer has a first birefringence when the first voltage is applied and a second birefringence when the second voltage is applied.

18 . A method comprising:

applying an electric field across a thickness dimension of an organic solid crystal thin film in an amount effective to change a refractive index and a birefringence of the organic solid crystal thin film.

19 . The method of claim 18 , wherein the change in the refractive index is at least approximately 0.001.

20 . The method of claim 18 , wherein applying the electric field comprises:

forming a segmented electrode over the organic solid crystal thin film; and

applying a voltage to the segmented electrode.