ISHAN TOPRE
Branch Unspecified
21 Apr 2012

# Can We Store Light?

When we generate electricity from sun light, some of the light escapes. Even so, can we have something to store light?

Please take into account, I am talking about storing light and not generating light.
21 Apr 2012
Light is just a form of energy. It's everywhere around us, stored perpetually in other forms. We just want to convert it into light energy whenever we need it.

ISHAN TOPRE

Branch Unspecified
22 Apr 2012
The_Big_K
Light is just a form of energy. It's everywhere around us, stored perpetually in other forms. We just want to convert it into light energy whenever we need it.
What you are talking about is solar panels. Where we

2. Convert it into Electricity
3. Use it as power for electrical gadgets.

I am talking about a box. Let us call it a magic box. Think rationally and tell me whether it is possible.
1. A magic box which I open.
2. Point it towards sun.
3. It stores light.
4. I close it.
5. I get light by opening it again.
6. I get only that much light which is stored in that box.

This thought occured to me while I was watching this advert.
22 Apr 2012
I'm not talking about solar panels. Your original post talked about 'storing light' and I said, since light is just form of energy, it's already stored in the Universe in different forms. What you're planning to do is already possible with solar cells that can power a small LED. Will do the same thing that you plan to do.

ISHAN TOPRE

Branch Unspecified
22 Apr 2012
OK let me change my question a bit.
How do we store "Light" in the form of "Light" itself? I do not want to store it in the form of heat (or any other form of energy) for instance. Is there any way?

aNaN

Branch Unspecified
22 Apr 2012
we know that light is a wave. A wave cannot be stored as it is. It has to be converted into some form.
For instance, take the case of sound. can you store sound as it is ? no. you have to convert it into some other form. same is the case with light

Jyothi Jo

Branch Unspecified
22 Apr 2012
Light is emission of energy from electrons(from sun). If light has to be stored in box it means energy have to be stored,since light is nothing but photons (energy packets). Energy is stored only when it is absorbed by the electrons in atoms i.e,the electrons are excited to higher orbit levels with this energy absorption and this electrons would not remain stable in its higher orbit and thus tries to come back to its original state of actual orbit (since every electron has its own potential energy).This electron doesn't fall suddenly .For example if you take an electron which absorbed energy and excited to third level orbit so within in a fraction of seconds it falls to second level by emitting little energy and again it falls from second to first level by emitting little energy where this energy is absorbed by the other electrons.So if you want to watch the light that you have stored then you need to emit the energy from the electrons that has been stored when you exposed to light, but electrons don't posses the energy you have given because it has already emitted to attain its original orbit level. Thus you can't see the light when you open the magic box . I think its clear.
23 Apr 2012
We may have to rephrase what Issue is taking issue with. Heat is also an electromagnetic wave. Yet we have no problem storing it as heat and getting it back as heat. Likewise can we think of a way of storing light as such and get it back?
Theoretically may be possible. Let us consider a chamber with totally reflecting walls with zero absorption. Let the light be injected into this and the injection port sealed. This can be done using a Kerr Optic Shutter.
The trapped light will keep bouncing around. If the Kerr shutter is opened the beam will jump out and escape.
How does that sound, Issue?

ISHAN TOPRE

Branch Unspecified
23 Apr 2012
bioramani sir. This is exactly what I was talking about. 😀 The magic box is indeed the apparatus you just explained. However it would be rather difficult (impossible) to get material with zero reflection.

Mr.Don

Branch Unspecified
23 Apr 2012
hmm, A Prism which cannot allow any light to escape through it!

ISHAN TOPRE

Branch Unspecified
23 Apr 2012
Mr.Don
hmm, A Prism which cannot allow any light to escape through it!
If the light escapes through prism, it will be of no use. We want to trap it.

bioramani sir. Do you know about the concept of perfectly black body? It uses lamp black as the inner coating. If it is replaced by glass mirror and the aperture is made to have OPEN/ CLOSE arrangement, it can be used to store light. How about it?

Mr.Don

Branch Unspecified
23 Apr 2012
Issue
If the light escapes through prism, it will be of no use. We want to trap it.

What about A Shutter with ms delay time.
23 Apr 2012
Mr.Don
hmm, A Prism which cannot allow any light to escape through it!
Not all that difficult Optical fibres use the property of total internal reflection. It should not be difficult to make a TIR chamber.
https://www.rkm.com.au/animations/Animation-Total-Internal-Reflection.html

https://www.nano-optics.org.uk/materials/pdfs/APL_99_081106.pdf
https://www.stanford.edu/group/fan/publication/Yu_PNAS_107_17491_2010.pdf
23 Apr 2012
Mr.Don
What about A Shutter with ms delay time.
The Kerr Optic shutter has a femtosecond action.
23 Apr 2012
Issue
If the light escapes through prism, it will be of no use. We want to trap it.

bioramani sir. Do you know about the concept of perfectly black body? It uses lamp black as the inner coating. If it is replaced by glass mirror and the aperture is made to have OPEN/ CLOSE arrangement, it can be used to store light. How about it?
These are called light spheres and used for measuring the total light output of lamps and such. Low level light signals are also trapped for measurement in spectrophotometers. I have used these for some measurements very long back.
https://www.rp-photonics.com/integrating_spheres.html
This is an interesting paper on storing and recovering light after a delay of 1.5 Secs, which is very long for light.
https://prl.aps.org/abstract/PRL/v103/i23/e233602

ISHAN TOPRE

Branch Unspecified
23 Apr 2012
Mr.Don Never thought of TIR and prism. Good thinking.

bioramani sir interesting application it is, the integrating sphere!

KenJackson

Branch Unspecified
06 Jun 2012
I have read that astronomers and cosmologists expect to see a bright circle around a black hole, if they ever get an unobstructed clear view of one. Why? Because some photons pass so close that their paths are not only bent by the black hole's gravity, but actually go into orbit. The bright circle will be caused by photons that weren't quite close enough to get sucked in, but were close enough to do a partial orbit or a few orbits or even quadrillions of orbits before finally breaking free.

So there may be a huge number of photons in orbit around every black hole in the universe. We could think of them as being in storage. (As an aside, time passes very slowly near the event horizon, so would the photons appear to be traveling in slow speed from our vantage point?)

That's not very practical, if you're looking for a practical way to store light. But I find it fascinating.

Vivien.hugo

Branch Unspecified
06 Jun 2012
Store light? This reminds me of the fairytales I've read when I was young?

the scientist

Branch Unspecified
06 Jan 2013
last year i have read about an experiment in which the light rays(photons) passing through a crystal halted just for a very small duration of time.............
we can call it ""storage of light""" though for small time but it is!!!!!!!!!!!!

Ankush Sharma

Branch Unspecified
07 Jan 2013
dear as far i know... the simple reason for your question is that because a light is an electromagnetic wave and it moves with the maximum possible speed in this universe(as far as discovered till today) that is 3E8 m/sec. so whenever you try to catch light in a container or any body, it will immediately leave the container before u can close it.

Howard Bell

Branch Unspecified
10 Feb 2013
Thinking laterally, you need to bend the light into a perfect circle in a vacuum so it is contained without loss (like the. magnets that contain Taurus style fusion reactors). The hitch is that gravity is equivalent to magnetism in this case, so you need to inject light perpendicular to and just above the event horizon of a black hole, and it will be stored in orbit without loss! getting it back out might prove tricky though!
ok prof hawking, I know it wouldn't, the example was illustrative of the difficulty of the engineering problem, given gravity as a tool!

ahmed sarfraz

Branch Unspecified
13 Jun 2014
Issue
What you are talking about is solar panels. Where we

2. Convert it into Electricity
3. Use it as power for electrical gadgets.

I am talking about a box. Let us call it a magic box. Think rationally and tell me whether it is possible.
1. A magic box which I open.
2. Point it towards sun.
3. It stores light.
4. I close it.
5. I get light by opening it again.
6. I get only that much light which is stored in that box.

This thought occured to me while I was watching this advert.

Actually, light is a form of transverse wave and the thing you are referring 'Storing the light in a box' is basically polarization of light. Polarization of a wave is exactly what you are referring to which means you can store it by opening the fictitious box and then when you open the box again, it comes out of it like it comes out from a torch. But the amount of light coming out is exactly the same as the amount stored. So, in short, light is a transverse wave and it can not be polarized. As simple as that. (I will love to get your feed back)

Howard Bell

Branch Unspecified
13 Jun 2014
I have pondered the very question you are asking many times, primarily as a means of information storage as apposed to energy storage. However the requirements are very similar. You talk about using a box when in fact you need to think outside of the box! 😀
The problem with light is it's tendancy to scatter energy every time it is reflected or passed through a less than 100% transparent medium. So we are essentially looking for:
a) The light equivalent of a super conductors
and
b) a perfectly (zero loss) reflective mirror.

Well the nearest you can get to perfect conductor of light is a vacuum, more commonly known as space!

As for the perfect mirror, I doubt there is one, but a low loss prism system could certainly be devised. (99.9995% reflecting mirrors for a specific wavelength ) were around 10 years ago!

So the main problem to overcome is the loss which is caused by the number of times the light reflects off each prism surface before the light is released from the system. This is of course a function of the distance between the prisms (i'm sure you can guess where i'm going with this by now!).

So how about we park our prisms in suitably far out positions in space so that the the distance is meaningfull (Somewhere just outside lunar distance would give us a 1 second buffer between reflections. Light would have to be highly coherent of course to avoid dispersion loss. So as long as the energy you are injecting into the prism loop in that 1 second is higher than the loss of the reflecting surfaces of the prism! bing bang bosh, you have yourself an almost infinite capacity light battery/prismatic accelerator/star wars weapon.
A 1 Mega Joule laser beam injected into say a 5 mirror loop at 1 light second apart (so a 5 second loop) would have a loop efficiency of 99.75% so it could build to a power of 400MJoule before losses matched input. (Doesn't sound much but it's probably good enough to knock down a ballistic missile or two!

I did also muse at one point that rather than reflecting light (and it's subsequent loss), how about we bend it, with the only thing known to bend light, Gravity! So first get yourself a black hole, then line yourself up with a space laser and the black hole, their should be an angle at which you can point the laser so that light almost but not quite falls into the event horizon. In that microscopic layer light will be bent just enough to perfectly orbit the event horizon in perpetuity! Hence big light battery!

Of course that last one's got a few obvious drawbacks, like you need to find a really clean black hole (with no accretion disk), and getting close to collect your light later might be a bit tricky!

As you can probably see it's a small step from any of the above solutions to chop that beam up into 'signal' and hey presto you have an almost infinite time/space RAM system for data!

Thats the kind of thing I muse over at 4am when I can't sleep.
13 Jun 2014
Ahmed sarfraz
So, in short, light is a transverse wave and it can not be polarized. As simple as that. (I will love to get your feed back)
I am afraid not.
It is longitudinal waves like sound waves that cannot be polarized. Only transverse waves like electromagnetic waves can be polarized. In any case storing light as light has little to do with its state of polarization.

https://home.strw.leidenuniv.nl/~keller/Teaching/China_2008/CUK_L01_handout.pdf

https://www.physicsclassroom.com/class/light/Lesson-1/Polarization