Generally, any light source emits EM waves of 0.4-0.7 mic.m wavelength for an input of 50Hz signal. How the input signal is converted to THz signal?
Dear Anvesh Kumar Nella
This is a very interesting question, but the question is little unclear to me.
The question implied you gave an input of 50 Hz to a system, I would like to know to which system you gave the input and how do you measure the output ?
With regards Dhanu Chettri.
Dear Dhanu
Let us consider a LED or a LASER to which we apply input signal and the output is visible light of THz frequency, but How?
Dear Anvesh
There are lots of possible answers depending on when system we used for example in LED as LEDs are simply diodes that are designed to give off light. When a diode is forward-biased so that electrons and holes are zipping back and forth across the junction, they're constantly combining and wiping one another out. Sooner or later, after an electron moves from the n-type into the p-type silicon, it will combine with a hole and disappear. That makes an atom complete and more stable and it gives off a little burst of energy (a kind of "sigh of relief") in the form of a tiny "packet" or photon of light.
Coming down to atomic level we know that when an electron goes from higher energy level to lower energy level it emitts EM Wave corresponding to the difference in the two energy level
There are two basic ways to get an electron from a higher energy level to a lower energy level: 1)spontaneous emission, and 2)scattering (which includes stimulated emission). In spontaneous emission, the electron seems to decay on its own to the lower energy state and gives off a photon in the process. In reality, quantum vacuum fluctuations are the engine behind spontaneous emission. A quantum fluctuation (which is like a particle briefly popping into existence), knocks the electron down to the lower level. The other way is scattering. If another electron, a photon, a phonon, a proton, etc, hits the electron, it can knock it down to the lower energy level. The energy it looses can be emitted as a photon or a phonon. When a bit of light (a photon) hits an electron in a higher level and there is an empty state in the lower level, it can get knocked down to the lower level and emit another photon in the process. This type of photon scattering is known as stimulated emission and is the core process inside LASER.
I hope it helps. If u still have doubts in this context I would be glade to discuss more about it
With my best regards.
Dear Dhanu
Can we able convert that light signal to it's equivalent sinusoidal of THz signal by using any appropriate APD.
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