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## Homework Statement

If a round trip gain in a 56.8 cm long laser is 5.16%, what is the net gain coefficient (g-[itex]\alpha[/itex]).

g is the small signal gain coefficient

[itex]\alpha[/itex] is the absorption coefficient

L-length of cavity

## Homework Equations

The Round Trip Power Gain: Gr= R1*R2* exp[(g-[itex]\alpha[/itex])*2L]

where I have to solve for (g-[itex]\alpha[/itex])

## The Attempt at a Solution

I have set R1=R2=1 assuming high reflectivity but I am not sure if this is alright.

First, solve as follows: ln(Gr)/2L = (g-[itex]\alpha[/itex])

Then, substitute the values for L and Gr:

ln(0.0516)/(2*56.8 cm) = -0.0260936057 = (g-[itex]\alpha[/itex])

However, I am not sure what this represents in terms of laser net gain coefficient and if I have correctly solved this (assuming R1=R2=1 and where Gr=0.0516 instead of 5.16% form.

I would appreciate some revision and explanation. I have read the textbooks from Milonni (Laser Physics) and Silfvast (Laser Fundamentals) but they don't really explain the meaning of this in detail. I have searched on google and this ebook helped a bit but I really can't say I understand completely... Any help is appreciated! THANKS!

Google ebook link: http://books.google.ca/books?id=DlW...EUQ6AEwAw#v=onepage&q=round trip gain&f=false