Recent content by lichen

From a classical perspective, linearly polarized light can be converted to circular by introducing a phase shift between the orthogonal modes. Could someone give me an explanation of how this works from a quantum mechanics perspective, starting from the fact that each photon has angular...

Basically I am asking, what if I spectrally filtered after the depolariser instead of before? The answer may be the apparently obvious: that everything would work fine. But the answer may also be: that is the same as filtering before the depolariser, and your filtered light will ultimately not...

Thanks for replying Andy. The depolarizer I had in mind was http://www.phoenix-photonics.com/products/polarizers_depolarizers/Depolarizers_V12_1102.shtml by Phoenix Photonics, since it operates over 1300nm and 1550nm regimes. They say the device can depolarize down to 0.1nm linewidth. If...

Can anyone comment on this please? The question is really, does placing an optical filter AFTER the depolariser, mean the depolariser doesn't have to handle such a low linewidth input?

My question relates to fiber optics, and probably also general optics. I have a broadband SLD source, which can be depolarized by a broadband fiber depolarizer. If I place a Fabry-Perot filter with low bandwidth between the source and depolarizer, I assume this reduces the linewidth going...

I'd like to ask another question if that's ok. Regarding the beat frequency created by two wavelengths: What if the two optical signals were not one single perfect wavelength each, but were instead comprised of certain known linewidths. Would this destroy the beat frequency detection method? In...

Combining fiber signals is trivial enough. I can't see why a polarizer would be required prior to photodetection. In fact, the two signals will be polarized on orthogonal axes of a single highly birefringent fiber, so taking this fiber straight to the photodiode should be sufficient for the...

Thank you both very much. I will try and summarise how I plan to use your advice. Hopefully this makes good sense. This will be a fiber optical system, with the two wavelengths on separate fibers. I will couple the signals into a single fiber, and then into the photodetector. The...

Hi optical engineers/physicists, I'm designing an optical sensor system, and it would be very beneficial if there was a method for determining the difference between two very close (down to tens of femtometers) optical wavelengths. The difference measured can be relative, although absolute...

Another link to a good site I've never seen before. This thread is a gold mine for good sites.

Ah, yes I see now. Thanks very much!

Is that your website? It's great! Very useful :-)

Easy question for those who know, I expect. It would help me understand though. Generally, wherever I look for information the equation curl E = - dB/dt is given, but in some areas I see the equation curl E(r,t) = j*omega*u0*H(r,t) where j is the imaginary unit, omega is angular...

The shrink-wrap-to-insulate method was recommended to me by a Professor who uses it in his group's own solenoids, as was the microbore tube method. It is an efficient way to water-cool the solenoid (the only alternative is to encase the whole structure in aluminium and have water rushing around...

Thanks. The solenoid will be air-core because I need to produce a very high strength pulsed field (5T). I will probably need some form of cooling, and I have been recommended that a good idea is to use microbore copper tube (of electrical grade copper) which I will shrink wrap. This will form...