Ch7_Polarization_ModulationLight

Ch7_Polarization_ModulationLight - Chapter 7 7.1...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 7 Polarization and Modulation of Light 2 7.1 Polarization A. State of Polarization 3 x y z E y E x y E y ^ x E x ^ (a) (b) (c) E Plane of polarization x ^ y ^ E (a) A linearly polarized wave has its electric field oscillations defined along a line perpendicular to the direction of propagation, z . The field vector E and z define a plane of polarization . (b) The E -field oscillations are contained in the plane of polarization. (c) A linearly polarized light at any instant can be represented by the superposition of two fields E x and E y with the right magnitude and phase. E ?1999 S.O. Kasap, Optoelectronics (Prentice Hall) 0 ˆˆ xo yo Ex E y E =− 4 • Polarization • Linearly polarized • Plane polarized • Unpolarized • Polarizer • Add electric field components vectorially cos( ) xx o E Et k z ω ) yy o EE t k z φ = −+ (1) (2) ˆ ˆ ) ) x y xo yo E xE yE t kz t =+= ) o t k z 0 E y E
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
5 z E y E x E E θ = k Δ z Δ z z A right circularly polarized light . The field vector E is always at right angles to z , rotates clockwise around z with time, and traces out a full circle over one wavelength of distance propagated. ?1999 S.O. Kasap, Optoelectronics (Prentice Hall) cos( ) x E At k z ω =− sin( ) y E k z 222 xy EE A += (5a) (5b) (6) 6 E y x E xo = 0 E yo = 1 φ = 0 y x E = 1 E = 1 = 0 y x E = 1 E = 1 = π /2 E y x E = 1 E = 1 = /2 (a) (b) (c) (d) Examples of linearly, (a) and (b), and circularly polarized light (c) and (d); (c) is right circularly and (d) is left circularly polarized light (as seen when the wave directly approaches a viewer) ?1999 S.O. Kasap, Optoelectronics (Prentice Hall) 7 E y x E xo = 1 E yo = 2 = 0 E xo = 1 E yo = 2 = /4 E xo = 1 E yo = 2 = /2 y x (a) (b) E y x (c) (a) Linearly polarized light with E yo = 2 E xo and = 0. (b) When = /4 (45 ° ), the light is right elliptically polarized with a tilted major axis. (c) When = /2 (90 ° ), the light is right elliptically polarized. If E xo and E yo were equal, this would be right circularly polarized light. ?1999 S.O. Kasap, Optoelectronics (Prentice Hall) 8
Background image of page 2
9 Polarizer 1 TA 1 Polarizer 2 = Analyzer TA 2 θ Light detector E E cos Unpolarized light Linearly polarized light Randomly polarized light is incident on a Polarizer 1 with a transmission axis TA 1 . Ligh emerging from Polarizer 1 is linearly polarized with E along TA 1 , and becomes incident on Polarizer 2 (called "analyzer") with a transmission axis TA 2 at an angle θ to TA 1 . A detector measures the intensity of the incident light. TA 1 and TA 2 are normal to the light direction. ?1999 S.O. Kasap, Optoelectronics (Prentice Hall) B. Malus’s Law 2 () ( 0 ) c o s II = 10 Liquid Crystal 垂直於光軸 垂直於光軸 平行於光軸 平行於光軸 11 Liquid Crystal 12 LCD There are many modes operation TN 90 deg twist STN 270 deg twist IPS in plane switching Patterned vertical alignment MVA multi-domain vertical alignment
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
13 14 7.2 Light Propagation in an Anisotropic Medium: Birefringence A. Optical Anisotropy 15 • Crystals are generally anisotropic – Many properties depend on the crystal direction • Electronic polarization depends on the crystal direction
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/06/2012 for the course ENGINEERIN 605 taught by Professor Rahmir during the Spring '11 term at Wisconsin.

Page1 / 18

Ch7_Polarization_ModulationLight - Chapter 7 7.1...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online