Wide-Angle and Broadband Polarization Converter

• US 20090040608A1
• Filed: 08/09/2007
• Published: 02/12/2009
• Est. Priority Date: 08/09/2007
• Status: Active Grant

• Current Assignee: InnoLux Corporation, University of Central Florida Research Foundation Inc. (State University System of Florida)
• Original Assignee: CHI MEI Optoelectronics Corporation, University of Central Florida Research Foundation Inc. (State University System of Florida)
• Inventors: Li, Wang-Yang, Wu, Shin-Tson, Wei, Chung-Kuang, Tsai, Chang-Ching
• Granted Patent: US 7,583,439 B2
• Time in Patent Office: Days
• US Class Current: 359/487
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles

Abstract

Apparatus and methods for a polarization converter comprising a polarization beam splitter for receiving an input light beam and allows a transverse magnetic to pass through the polarization beam splitter and reflects a transverse electric wave and a diffraction grating having a reflectivity and polarization convertible grating for receiving the transverse electric wave reflects back a reflected transverse electric wave having a polarization rotation. The broadband wide-angle polarization beam splitter can be alternative optical elements such as a prism or an optical device having multi-layered films. The diffraction grating can be a diffraction grating having alternating parallel protrusions and recesses, metallic diffraction grating, metal-coated diffraction grating, metal-coated multi-layered diffraction grating, non-metallic reflective material surface grating, volume grating, a multi-layer grating, diffractive grating having sub-wavelength grating periods or diffractive grating having multi-orders diffraction gratings. The diffraction grating can have alternative shapes such as binary, trapezoidal, sinusoidal, parabolic, triangular and Gaussian.

Claims

1. A polarization converter comprising:

a polarization beam splitter for receiving a light beam, passing a first polarization wave of the light beam through the polarization beam splitter and reflecting a second polarization wave of the light beam; and

a diffraction grating having a reflectivity and a polarization convertible grating for receiving the transverse electric wave and reflecting back an elliptically polarized wave having a polarization rotation.

2. The polarization converter of claim 1, wherein the first polarization wave is as transverse magnetic wave, and the second polarization wave is a transverse electric wave.

3. The polarization converter of claim 1, wherein the broadband wide-angle polarization beam splitter comprises:

a prism.

4. The polarization converter of claim 1, wherein the polarization beam splitter comprises:

an optical device having multi-layered films.

5. The polarization, converter of claim 1, wherein the diffraction grating comprises:

a diffraction grating having alternating parallel protrusions and recesses.

6. The polarization, converter of claim 1, wherein the diffraction grating comprises:

a metallic diffraction grating.

7. The polarization converter of claim 1, wherein the diffraction grating comprises:

a metal-coated multi-layered diffraction grating.

8. The polarization converter of claim 1, wherein the diffraction grating comprises:

a non-metallic reflective material diffraction grating.

9. The polarization converter of claim 1, wherein the diffraction grating comprises:

a surface grating.

10. The polarization converter of claim 1, wherein the diffraction grating comprises:

a volume grating.

11. The polarization converter of claim 1, wherein the diffraction grating comprises:

a multi-layer grating.

12. The polarization converter of claim 1, wherein the diffraction grating comprises:

a diffractive grating having sub-wavelength grating periods.

13. The polarization converter of claim 1, wherein the diffraction grating comprises:

a diffractive grating having non evanescent diffraction orders.

14. The polarization converter of claim 1, wherein the diffraction grating comprises:

a diffractive grating having multi-orders diffraction grating.

15. The polarization converter of claim 1, wherein a shape of the diffraction grating is selected from a group consisting of:

binary-shaped gratings, trapezoidal-shaped gratings, sinusoidal-shaped gratings, parabolic-shaped gratings and Gaussian-shaped gratings.

16. The polarization converter of claim 1, wherein the polarization beam splitter comprises:

a waveguide cavity structure to guide the transmitted wave in the desired direction for polarization conversion.

17. A method for efficient polarization conversion of a light beam comprising the steps of:

receiving a light beam at a polarization beam splitter;

passing a first polarization wave of the light beam through the polarization beam splitter;

reflecting a second polarization wave of the light beam from the polarization beam splitter to a diffraction grating;

reflecting an elliptically polarized wave from the diffraction grating back to the polarization beam splitter;

receiving the reflected elliptically polarized light at the polarization beam splitter; and

repeating the steps for multiple-bouncing between the polarization beam splitter and the diffraction grating to achieve high polarization conversion efficiency.

18. The method of claim 17, wherein the elliptically polarized wave having a mixture of the first polarization wave component and second polarization wave component with a phase difference.

19. The method of claim 17, wherein the first polarization wave means transverse magnetic wave, and the second polarization wave means transverse electric wave.

20. The method of claim 17, further comprising the step of:

aligning the polarization beam splitter in parallel with the diffraction grating to form a polarization rotation parallel resonator.