Optical Amplification

[Music] money welcome to introduction to photonics so this week we've been looking at how photons interact with matter and specifically we have been trying to like analyze light generation and amplifications will continue the discussion with a little bit of a practical example so you know we'll look at the example of why we need

amplification right so till the last lecture we were looking at how amplification or what are the conditions required to achieve light amplification today we will look at why we need amplification we'll take the specific example of optical communication right so it is one of the you know really widespread application of optics in in

today's world so we will look at the that specific example and we'll look at why we might need an optical amplifier in that case and we will try to go ahead and build an optical amplifier today okay so that's what we're going to try to do today just to give a quick recap

we started with looking at an elementary system with consisting of two energy levels we will look tracking all the different processes between those two energy levels absorption spontaneous emission stimulated emission and then we were trying to quantify this emission probability density which actually it's representing the stimulated emission term so may think of it as the

stimulated emission probability density and the probability that stimulation stimulated emission should happen and and we came up with this expression and then we were trying to look at specific cases specific we're trying to make some specific observations and one of the first observations we made was what if we are looking at a source where