ECE615_Lecture_22 - In simple cases we use power expansion:...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: In simple cases we use power expansion: But does not work for all cases, such as Saturable Absorption. Lecture 22 Nonlinear Optics in the Two-Level Approximation (1) (2) 2 (3) 3 ( ) ( ) ( ) ( ) ... P t E t E t E t = + + + 2 n c 1 s I I = + a b is weak-field absorption. is saturation intensity (and optical constant for the material). Expands to: Only converges for , which is not always realistic. Use nonperturbative approach. 1 2 I n c E = s I ( 29 ( 29 ( 29 2 3 1 ... s s s I I I I I I =- +- + s I I < Collection of 2-level atoms: (1) no damping effects ( ) H H V t = + a a E = b b E = 0, | | nm n nm H E n H m = = ( ) ( ) V t E t = - aa bb aa bb V V = = = = (omit the signs of vectors and dot-product) 2 * ( ) ba ab ba V V E t = = - aa ab ba bb = * ab ba = [ ] ( 29 ( 29 ( 29 , = nm nm nm nm nv vm nv vm v i i H H H i H V - = - = - -- [ ] nm nm nm nv vm nv vm v i i V V = --- ( 29 ( 29 ( 29 ba ba ba ba bb aa bb ba ab ba ab aa ab ba ab ba i i V i V V i V V = - +- =- =- 1 aa bb aa bb + = + = 3 (1) Closed two-level atom upper level (2) decays to the lower level at a rate lifetime of the upper level is given by Typically, the decay of the upper level would be due to spontaneous emission (population remains within system, i.e. closed....
View Full Document

This note was uploaded on 01/10/2011 for the course ECE 615 taught by Professor Shalaev during the Fall '10 term at Purdue University-West Lafayette.

Page1 / 14

ECE615_Lecture_22 - In simple cases we use power expansion:...

This preview shows document pages 1 - 4. Sign up to view the full document.

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