optical diodes, was Re: Curvature of Space

[John Gastineau <gastineau@mindspring.com>]

At 07:41 PM 2/23/98 , you wrote:
> Faraday (1845) used three solenoids and a battery of Daniel cells to 
> discovery the eponymous effect - which you can demonstrate with
> a long tube of distilled water in a solenoid. The polarization rotation
> effect is rather meager however.

There's a neat device in ring lasers known as an "optical diode." Its
effect is to let light through in one direction, but not in the other.
Not literally, but in effect. The device depends on the Faraday effect. 

(Ring lasers depend on one-way travel of light through a cavity of
three or more mirrors. The light is thus a traveling wave rather than a
standing wave, and far more energy can be extracted from the active medium.)

I'll let everyone puzzle on this for a day before explaining. ;-)

JEG
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