Hi
Suppose an electro-optical structure that by applying an external voltage, the output light can be in the ON or OFF states. The structure has one input port and one output port. Now, Is this structure an electro-optical switch or an electro-optical modulator?
Kind regards
Greetings.
1.In my opinion, there is no significant difference between an electro-optical switch (EOC) or a modulator (EOM), since they solve one problem by a functional attribute: EOC and EOM perform switching of channels and data flow by interrupting or changing the direction of light flux in the network.
2. Another question is what effect is the basis for obtaining the functional (EO: electro-optical Pockels effect, frequencies - hundreds of GHz; magneto-optical - MO, frequencies - hundreds of MHz). If necessary, I can inform the sources of information (Russian language).
3. I draw your attention to the existence of another type of devices - optoelectronic switching matrices - OESM (based on lines of low-power optocouplers of the LED - pin PhDiod type, frequency - hundreds of MHz) and their planar elements (in the form of UHF micropower optocouplers, optoelectronic logic elements and / or switches *, frequencies - in units of GHz: see my work in this area - RG profile).
4.If my answer and / or the information given by me were useful to you, please mark and / or recommendation.
Best regards, Proskurin N.P., PhD, docent NUZP, UA.
Unfortunately language is flexible and people use "switch" and "modulator" interchangeably, so there isn't a definitive answer to your question. Any distinction I make between them you will be able to find lots of places in literature that use the terms differently. However, I will tell you what I think of when I hear those terms.
There are plenty of places where "switch" means "on - off", for example a light switch. However, in most cases (especially in network communications) "switch" means from one output to another. An input signal is "switched" between output ports (whether 2 or many) as in "switch from A to B". This is, for example, the meaning of "switch" even for rail-road tracks. "modulation" on the other hand rarely refers to more than one output. A single signal at the input is being modified at the output. The definition of "modulate" is "vary the strength, tone, or pitch of", or "alter the amplitude or frequency of". So a "modulator" modulates the input signal creating an output with varying amplitude or frequency.
The confusion comes because almost any device that can "switch" between A and B is also, by definition, "modulating" the strength of the signal on both A and B. There are many devices which can be used as switches between 2 or more ports, and for almost all of them there is an essentially identical device with only one output port called a "modulator". If you buy a switch and only use one of the output ports, then it is being used as a modulator. You can see how the lines blur.
However, I don't think it has to be overly complicated. Whether you use the term "switch" or "modulator" is not really a description of the device, but rather indicates how you are using it. If the primary purpose and use of a device in your system is to vary the amplitude or frequency of the input signal to create a modulated output signal, then it is a modulator. On the other hand, if the primary purpose and use is to switch a signal between output A and output B, then it is a switch.
The only real difficulty is when the device is being used to modulate a signal into only two states: on and off. Because of the analogy to a light switch, it is pretty easy to call that a switch. Me, I still call it a modulator.
A possible difference is that a switch switches between on and off, a modulator analog adjusts the level of the signal, thus allows to set any amplitude value between zero and maximum
I think the is no difference and In modulator an electro-optic effect is used to modulate a beam of light.also you can see the operation of switches.
Mike Albert Thank you for your comprehensive and convincing answer.
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