Lasers Chapter 10 - Lasers PH 645/ OSE 645/ EE 613 Summer...

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Lasers PH 645/ OSE 645/ EE 613 Summer 2010 Section 1: T/Th 2:45- 4:45 PM Engineering Building 240 John D. Williams, Ph.D. Department of Electrical and Computer Engineering 406 Optics Building - UAHuntsville, Huntsville, AL 35899 Ph. (256) 824-2898 email: williams@eng.uah.edu Office Hours: Tues/Thurs 2-3PM JDW, ECE Summer 2010
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Chapter 10: Laser Pumping Requirements and Techniques Excitation or pumping threshold requirements Pumping pathways Specific excitation parameters for optical pumping Specific excitation parameters for particle pumping Cambridge University Press, 2004 ISBN-13: 9780521541053 All figures presented from this point on were taken directly from (unless otherwise cited): W.T. Silfvast, laser Fundamentals 2 nd ed., Cambridge University Press, 2004. Chapter 10 Homework: 7, 9, 10, 14(Bonus)
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Excitation Pumping Threshold Requirements Applied excitation flux is defined as the product of the density of the pumping state and the rate of excitation: N Γ By applying a known excitation rate, one can determine the stead state solution for the upper state density Where N j is the density in the state j from which the excitation occurred. In many cases this would be the ground state previously written as o or l In other cases such as organic die lasers, N j is the dye concentration mixed into the solvent From our expressions for gain, and assuming that the pumping flux generates significantly more states in u than in the lower state, then one can express the equations for gain as:
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Direct Pumping: Upper level excitation from a source (or target) level j which is generally the highly populated ground state, o, of the laser species Optical Pumping: involves the absorption of pumping light within the gain medium Common process for solid state and organic die lasers We define B ou as a coefficient related to the topical transition probability A uo of the absorbing transition. Particle Pumping: excited particle collision is used to transfer energy within the gain medium Common process for gas and semiconductor lasers K ou is the reaction probability that a collision that a particle p will collide with the laser species and excite it from o u Pumping Pathways: Direct Pumping
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Particle Pumping: excited particle collision is used to transfer energy within the gain medium Common process for gas and semiconductor lasers K ou is the reaction probability that a collision that a
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Lasers Chapter 10 - Lasers PH 645/ OSE 645/ EE 613 Summer...

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