Ring laser
A ring laser is a laser in which the laser cavity has the shape of a ring. Light in ring lasers has two possible directions of propagation: clockwise and counter-clockwise.
Ring lasers are sometimes modified to allow only one direction of propagation by placing a device into the ring which leads to different losses for different propagation directions. For instance, this could be a Faraday rotator combined with a polarizing element.[1]
One type of ring laser design is a single crystal design, where light reflects around inside the laser crystal so as to circulate in a ring. This is the "monolithic crystal" design, and such devices are known as "non-planar ring oscillators" (NPROs) or MISERs.[1] There are also ring fiber lasers.[2][3]
Ring lasers have several applications. Currently the most widespread application is the ring laser gyroscope. If a ring laser is rotating, the two counter-propagating waves are slightly shifted in frequency and a beat interference pattern is observed, which can be used to determine the rotational speed.
Semiconductor ring lasers have potential applications in all-optical computing. One primary application is as an optical memory device where the direction of propagation represents either 0 or 1. They can maintain the propagation of light in exclusively the clockwise or counterclockwise direction as long as they remain powered.
[edit] References
- ^ a b "Ring Lasers". Encyclopedia of Laser Physics and Technology. http://www.rp-photonics.com/ring_lasers.html. Retrieved 2009-08-19.
- ^ I. N. Duling III, “All-fiber ring soliton laser mode locked with a nonlinear mirror”, Opt. Lett. 16 (8), 539 (1991)
- ^ L. E. Nelson et al., “Ultrashort-pulse fiber ring lasers”, Appl. Phys. B 65, 277 (1997)
[edit] See also
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