Diffraction & Interference

[Music] in the last lecture I was just showing you the course outline and as part of that what I did not specifically mention the learning outcomes for the course itself so what are these first of all we are trying to identify the fundamental principles of photonics and light matter interactions then we're going to try to

develop an ability to formulate problems related to photonics photonic structures processes and analyze them and finally we're going to try to identify processes that help to manipulate the fundamental properties of light and of course that's what we saw in the last lecture we were trying to identify three modules so those three modules are consistent with

the learning objectives of this course so let's go back and have a quick recap of where we were yesterday we were starting with general statement as to why we should be interested in photonics we were trying to list down a number of applications where photonics play a central role and then we went on to say

you know when you look at how we try to analyze the photonics processes we start with ray optics where as Fermat mention light travels in straight lines it's a very simple concept and then we say okay ray optics cannot explain everything some of which we're going to actually look into a little more detail today

so concepts like wavelength and phase of light is not something that you can capture in ray optics so you next certainly have to go into wave optics and then of course even the wave optics is not sufficient to explain you know concepts that are based on polarization of light so to capture those we go to

electromagnetic optics which started with Maxwell you know making his declaration around the mid eighteen hundreds that light travels as electromagnetic waves and then I got this wrong the year wrong Planck actually came up with this paper in 1900 that essentially was saying that light emission and absorption are quantized and then that was followed by Einstein's