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Multi-wavelength generating component.

Hello I'm somewhat new to electronics. After doing some research I have noticed that components used to emit EM radiation, ranging from magnetrons to simple LEDs seem to have something in common. They only emit one predetermined wavelength of EM radiation. In the case of LEDs this is preset by the materials that were used in the construction of the diode. I know there's RGB LEDs that can emit the three primary colours, but this is just essentially just 3 different colour diodes combined into one rather than a single component. Just wanted to know whether there are any components that can emit a wide range of wavelengths, maybe by changing what current or voltage it is fed.

I think the answers probably no, but I'll still learn something.
 

JimB

Super Moderator
Most Helpful Member
Welcome to ETO.

First of all, a bit of terminology...
The expression "wavelength" is generally only used when referring to infra-red, visible and ultra-violet light.
For lower frequency things, the commonly expression is "frequency".
This is not a hard and fast rule, there are many exceptions.

Wavelength and frequency are related by the equation:

frequency = 300,000,000/wavelength

Where frequency is in Hertz, and wavelength is in metres.

To your main question...
Yes, there are things which can emit a range of frequencies (wavelengths).
A white LED.
White light is made up of a broad spectrum of frequencies.
Another example would be a simple old fashioned incandescent lamp.
When the filament is up to normal temperature, it emits white light.
Run the thing on a reduced voltage and you will get an orangy red colour.

As for a magnetron, where you are getting into the field of "radio", as a general rule we only want one frequency at a time.
Otherwise radio stuff would not work very well.

As a supplementary bit of information, sinewaves have a single frequency component.
Any waveform which is not a sinewave has several frequency components.
For example, a square wave with a frequency of 1MHz, will have components at 1MHz, 3MHz, 5MHz, 7MHz....etc
In theory, all the odd harmonics up to infinity.
In practice not so much!

JimB
 

AnalogKid

Well-Known Member
Most Helpful Member
"Range" is a bit ambiguous. Anything that processes a complex waveform (something other than a simple sine wave, like a square wave or music) is processing or emitting multiple frequencies simultaneously. Look up the Fourier Series to see examples of the multi-frequency content of square, triangle, saw, and other wave shapes.
 
Thank you both for replying! Yes I would be ignorant of the terminology as far as engineering goes as I get my knowledge about waves from a physics course rather than from an engineering course, good to know though. The only thing I was taught about frequency was that it is the number of wave cycles that pass a point per second. I actually meant to look up whether incandescent bulbs did produce different wavelengths based on voltage, they're probably the closest thing to what I had in mind.
 
Just in case anyone needs it, although I couldn't find one emitter that could create multiple wavelengths (except the fluorescent bulb). I did find an interesting component that can house up to 7 different diodes at once and they can all be of different wavelengths, you can even have them custom build. It's from this website, unfortunately I get the impression that they manly deal with companies that buy large amounts of the diodes rather than individual hobbyists or students.
 

unclejed613

Well-Known Member
Most Helpful Member
a standard RGB LED is probably what you are looking for, or about as close you will get.... if you need infrared and ultraviolet, there are IR LEDs and UV LEDs available as well. if you are looking for a light source that is monochromatic and tunable ( emits only one wavelength and that wavelength can be changed) the only option is a tunable laser, and these are not only expensive, but somewhat narrow in their tuning range. you won't for instance find one that covers the whole visible spectrum.
 

gophert

Well-Known Member
Most Helpful Member
a standard RGB LED is probably what you are looking for, or about as close you will get....
Is that really your comment to the OP's question? Are you a used car salesman? Read his ORIGINAL POST below.

I know there's RGB LEDs that can emit the three primary colours, but this is just essentially just 3 different colour diodes combined into one rather than a single component. Just wanted to know whether there are any components that can emit a wide range of wavelengths, maybe by changing what current or voltage it is fed.
 

unclejed613

Well-Known Member
Most Helpful Member
Thanks for telling me about the tunable laser I hadn't heard of that!
just keep in mind, they are expensive, and usually limited to a very narrow tuning range, like a couple hundred nM. most tunable lasers with a wide tuning range are tunable from red to somewhere in the near IR range (700nNM-1100nM).
 

unclejed613

Well-Known Member
Most Helpful Member
that is a pretty large tuning range, but as i said these aren't cheap or small.
 

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