Ring structures laser resonators

One class of laser resonators is based on circular structures like spheres, disks, and rings. In these structures, the optical modes form closed circular loops and... 

Two classes of material will be described here - the metal dithiolenes and rare earth metallocenes. In the metal dithiolenes a strong, low energy pi-pi transistion occurs in the near IR (9.10). This can be tuned from about 700 nm to 1400 nm by altering the metal ion, substituents or charge state of the dithiolene. The dithiolenes are particularly attractive because of their optical stability which has been exploited in their use as laser Q-switch materials. In the rare earth complexes the near IR band is provided by/-/transistions of the rare earth ion rather than the cyclopentadienyl ring structure various nonlinear optical phenomena have been observed in glasses incorporating similar ions. Previous studies have shown that dicyclopentadienyl complexes such as ferrocene have off-resonant nonlinearities similar to nitrobenzene or carbon disulphide (11-13)... 

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