13 Optical Gain. 2010

13 Optical Gain. 2010 - Optical Gain Implicit in the...

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: Optical Gain Implicit in the concept of stimulated emission is the idea that if a photon can either be absorbed or stimulate the emission of another photon depending on the state of the atom it encounters, then by arranging the atoms so that N 2 > N 1 , we can produce more photons than are incident on our population of atoms, i.e. we can have optical gain. N 2 N 1 I( ) z I( ) + I( ) Detector Polarizer Optical Gain (cont) I( ) will be either positive or negative depending on the relative rates of stimulated emission or absorption in z. If I( ) is monochromatic and polarized I( ) = I = c then we can calculate: 21 2 2 12 1 1 21 2 ( )- ( ) 1-A ( ) 2 4 dN I dt I I B g N z h c g I B g N z h g c g N z h = = Stimulated Emission Absorption Spontaneous Emission Optical Gain (cont.) 2 21 2 1 1 2 21 2 1 1 ( ) ( ) ( ) ( , ) ( ,0) o z h g I B N N g I z c g I dI h g B g N N I z dz c g I I z I e =- =- = = If and are small, the last term (spontaneous emission) is negligible. Then....
View Full Document

This note was uploaded on 02/23/2011 for the course EE 474 taught by Professor Lingo during the Spring '11 term at USC.

Page1 / 16

13 Optical Gain. 2010 - Optical Gain Implicit in the...

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