Is Frequency Doubling the Secret to Producing Red Light in Laser Pointers?

[EspangeBob]

Is it possible to change light wave frequency via a media filter?
or if it is impossible is there any why to do it?

without changing light direction !

 

[berkeman]

Welcome to the PF.

To change the light frequency, you would normally need some non-linear process to generate higher harmonics or to modulate the frequency of the light. Is that what you are asking about?

When light changes media as it propagates (like when it goes from air to glass), the frequency stays the same but the propagation velocity changes (so what happens to the wavelength?).

And what do you mean by "media filter"?

 

[anorlunda]

Remember conservation of energy. The energy of a photon is proportional to frequency.

So the power out of a passive filter is the power in, minus any absorption or reflection.

 

[Baluncore]

Is it possible to change light wave frequency via a media filter?

It is not possible to change the frequency of light without loss of direction.

Light can reduce it's wavelength slightly while propagating through slower materials such as glass, but the original wavelength is restored when the light exits the material.

The closest analogy to your “wanted” effect is fluorescence, where a molecule excited by a shorter wavelength photon then releases a lower energy photon with longer wavelength. But the direction information will be lost during the quantum conversion.

 

[anorlunda]

Is it possible to change light wave frequency via a media filter?
or if it is impossible is there any why to do it?

without changing light direction !

Can you explain better what you are trying to accomplish?

 

[hmmm27]

Is it possible to change light wave frequency via a media filter?
or if it is impossible is there any why to do it?

without changing light direction !

The lasing medium in most laser-pointers produce infrared light. That's sent through a frequency-doubling crystal to produce red.

https://en.wikipedia.org/wiki/Laser_pointer

https://en.wikipedia.org/wiki/Second-harmonic_generation