EDFA Introduction

[Music] okay good morning welcome to yet another session of introdu photonics we started this particular module several lectures ago we said we're going to identify the fundamental principles of photon interaction with atoms and specifically analyze light generation and amplification so as part of this what we have been considering is amplification of light and then you know with respect

to the amplification we said okay we would typically deal with a three level system or a four level system right like this and then in terms of analyzing such systems we said we will first of all start with the rate equations right we will learnt how to write rate equations and then we will assume a certain

condition what condition steady state condition because that's when that's the condition we are typically interested in and we said we assume steady state condition then DN 2 over DT and D n1 over DT equated to zero so that allows us to come up with a relatively simplified expression for the inversion and we are trying to get that inversion

as a function of the pumping rate as well as you know as a function of the amount of signal photons that are going through the amplifier ok so what we will what we are going towards beyond this is you know we start from an amplifier and then how can we build a laser from this

so we're going to start incorporating feedback and then we will say how to get a laser based on the sample fire maybe that's what we will start doing from the Lexx next lecture onwards but for today I thought we could just see how well equipped we are to take up a practical problem okay so for this I

thought it'd be a good idea to go back and consider this quiz problem this is actually quiz two last year of the year before in 2016 right so this is quiz 2 paper and and then from that paper there is this one question on amplification using a beam dope silica fiber so let us