Question

What is the role of refractive index in photonic devices? Give examples from LED, diode laser and photodetector, and waveguides?

Answer 1

consider photonic devices like LED
in LED, the light has to come out of the glass bulb only uptill certain angles so as to maintain a desirable spot of the emitted light
this can be acheived by total internal reflection, by which means light escapes bulb upto a certain angle
now total internal reflection is a property due to refratction of light

similiarly, for diode laser, photodetectors and waveguides the refractive index of the medioum coating the device plays an
important role to control the role of the device using total internal reflection which is a functino of the refractive index of this transparent coating material