Question

Discuss the effect of saturation in two the first homogenouly broadend and the second is inhomogeneously broadened from two points of views (i) gain variation a gainst frequency

(ii) number of axil modes that can Oscillate in a laser cavity

use figures to strengthen your answers .

Answer 1

for represented optor al laser gain spectrum is gain narrow band glu) HB road snel ana g - modes The typical value of longitudinale ce ana can be 7) of two Sadraton behavior of system types. (o la homogenous sous broadening the entire gain curce is reducede under saturation but the shape remains unchanged. ge) sunsaturated gain > satur and ginn the In in hom nogenous bro aclining sadurating signal is having peak al. vs. so it gaan only saturates in band around the Frequency. narrow 2o.

g(2) Hunsaturahl gerin > saturated gain Case broadening in Iberefore inhomo nogenow the broadening of atoms coith varying Aquenties. is resulted from Collection resonant centes N2 22 In homogenous broadenia biser trasida the rate equator for leser levels. dino Rental (W1-o) Icon dN! Riento (eo-20o) NzA21 - de za how is given by. dt saturadon indensity Is (w2 20 to will R1 (od-wote time which depends of lifetime of .booth uppe and lower laser levels TR.) Recovery

probe beam is th gain measured coefficent is cleferminal narrow will be half of the small signal gai. As the frequency tined aowss leur wine, satroatica gain from saturatece population invenion 216-wo) cóleo.coo) 1/27/13 I s intensity of band In an inhomogenous broachend gain median beam of intense, eradiation wirst frequency clou to is resulted in broden intease gain colifficicna incainned by probat Co in inhomoges ous broadening case çoci all modes above threshold oscollate narrow band cohen a منا dering there othe to gane mode spauong 2 C 22 Eco 2L laser olp

caso and equal. sarlasand guin t. teresadd value for afoms. cohich can. In homogenous only highest gain modes oscillates. So the entire gan Curce safurates until the gain loss for oscillating mode becomes will be for the other modes this gain less than loss. de mo de In Homogenoud broadend laser transition as the sumping is : incarard from zero, population inversion r and small coefficient xo (6) Parocases. As the gain coefficient increase until threehold conclition is met for cavity mode closest to line centre causing onset of oslollation on that mocle. Caround ist). Further recrease will hale no effecti. pumping where as inhomogenous broadening the. muersion is only clamped to cavity population inderact with frequency of Oscillating while pumping. As pumping increase.

x/a.wolf Threshold number of osullating modes increases as well as output power of each od lilled, De cillating moclo LA op pover longitudiney moche. Care for : homogenow. broadened gransition f Threshold 4/5.0 pour 22 ALL trhu Cast for Klaw.com inhomogenoue broadend /sunsition ✓ o/P Co-w pow -multin modle Oscillalan w