High Reflectivity LCOS Device

Patent metadata

Field	Value
Publication number	US-2016291405-A1
Application number	US-201415038037-A
Country	US
Kind code	A1
Filing date	Nov 13, 2014
Priority date	Nov 21, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

Described herein is a spatial light modulator ( 15 ) for modulating the phase, retardation or polarization state of an incident optical signal propagating in a first dimension. The optical phase modulator ( 15 ) includes a liquid crystal material ( 17 ) and a pair of electrodes ( 19 and 21 ) for supplying an electric potential across the liquid crystal material ( 17 ) to drive liquid crystals in a predetermined configuration. Modulator ( 15 ) also includes a diffractive optical element ( 29 ) disposed adjacent a first electrode ( 19 ). Element ( 29 ) includes a first array of diffractive elements ( 31 ) formed of a first material having a first refractive index and extending in a second dimension substantially perpendicular to the first dimension. Elements ( 31 ) are at least partially surrounded by a second material ( 33 ) formed of a lower refractive index.

First claim

1 . A spatial light modulator configured to modulate the phase, retardation or polarization state of an incident optical signal propagating at least partially in a first dimension, the optical phase modulator including:
a liquid crystal material; a pair of electrodes for supplying an electric potential across said liquid crystal material to drive liquid crystals in a predetermined configuration; and a first diffractive optical element disposed between the electrodes for at least partially reflecting the incident optical signal; wherein the diffractive optical element includes a first array of diffracting formations formed of a first material having a first refractive index and extending in a second dimension substantially perpendicular to the first dimension, the formations being at least partially surrounded by a second material formed of a lower refractive index.

2 . A spatial light modulator according to claim 1 wherein the first diffractive optical element is disposed between the liquid crystal material and the first electrode.

3 . A spatial light modulator according to claim 1 wherein the first diffractive optical element is disposed within the liquid crystal material.

4 . A spatial light modulator according to claim 1 wherein the first material is silicon and the second material is silicon dioxide (S i O 2 ).

5 . A spatial light modulator according to claim 4 wherein the thickness of the silicon material in the first dimension is in the range of 100 nm to 400 nm.

6 . A spatial light modulator according to claim 5 wherein the thickness of the silicon material in the first dimension is 200 nm.

7 . A spatial light modulator according to claim 5 wherein the thickness of the silicon dioxide material in the first dimension is in the range of 100 nm to 400 nm.

8 . A spatial light modulator according to claim 7 wherein the thickness of the silicon dioxide material in the first dimension is 250 nm.

9 . A spatial light modulator according to claim 1 wherein the diffracting formations are spaced apart in the first dimension by a fixed periodicity.

10 . A spatial light modulator according to claim 1 wherein the diffracting formations are spaced apart in the first dimension by a variable periodicity.

11 . A spatial light modulator according to claim 1 wherein the diffracting formations are spaced apart in the first dimension by a periodicity that is in the same order as the wavelength of the incident optical signal.

12 . A spatial light modulator according to claim 11 wherein the periodicity is in the range 500 nm to 1000 nm.

13 . A spatial light modulator according to claim 12 wherein the periodicity is 850 nm.

14 . A spatial light modulator according to claim 13 wherein the duty cycle of the first array is 0.35.

15 . A spatial light modulator according to claim 1 including a second diffractive optical element disposed between the electrodes and including a second array of diffracting formations.

16 . A spatial light modulator according to claim 15 wherein at least one of the first or second diffractive optical elements is disposed within the liquid crystal material.

17 . A spatial light modulator according to claim 16 wherein the first and second diffractive optical elements are disposed within the liquid crystal material.

18 . A spatial light modulator according to claim 15 wherein the first and second arrays have different periodicities.

19 . A spatial light modulator according to claim 15 wherein the first and second arrays have different thicknesses in the first dimension.

20 . A spatial light modulator according to claim 3 wherein the first diffractive optical element also functions as an alignment layer to align the liquid crystals within the liquid crystal material.

21 . (canceled)

22 . A method of manufacturing an optical phase modulator including:
a) providing a first electrode having a two dimensional array of individually electrically drivable cells; b) depositing a first layer formed from a first dielectric material onto the electrode; c) depositing a second layer formed from a second dielectric material onto the first layer; d) etching a plurality of trenches through the second layer, the trenches extending longitudinally in a first dimension and being spaced apart in a second lateral dimension by a fixed or variable spacing; e) depositing a third layer formed from the first dielectric material onto the second layer and into the trenches; f) depositing a liquid crystal material over the third layer; and g) mounting a second electrode onto the liquid crystal material.

23 . (canceled)

24 . (canceled)

25 . (canceled)

26 . (canceled)

27 . (canceled)

28 . (canceled)

29 . (canceled)

30 . (canceled)

31 . (canceled)

32 . In an LCOS device of the type having a liquid crystal material for control of the relative phase of orthogonal polarizations in the presence of an external electric field, and a reflective surface structure for reflecting light transmitted through the liquid crystal material back through the material, a method of improving the reflectivity operation of a LCOS device, the method including the step of:
a) depositing at least a first diffractive structure between the reflective surface and the liquid crystal material.

33 . A method according to claim 32 including the step:
b) depositing a second diffractive structure between the reflective surface and the liquid crystal material.

34 . A method according to claim 32 wherein said first and second diffractive structures have different periodicity.

35 . A spatial light modulator according to claim 1 wherein the first and second materials are non-metallic.

Assignees

• Frisken Steven James
• Wu Qihong
• Finisar Corp

Inventors

• Frisken Steven James
• Wu Qihong

Classifications

• G02F1/136277

  formed on a semiconductor substrate, e.g. of silicon · CPC title

• G02F1/133553 Primary

  Reflecting elements (associated to illuminating devices G02F1/133605) · CPC title

• G02F2203/22

  diffractive · CPC title

• G02F1/133504

  Diffusing, scattering, diffracting elements (associated to illuminating devices G02F1/133606) · CPC title

• G02F2203/12

  spatial light modulator · CPC title