Spherical optical cavities have been used to filter laser beams based on frequency and/or wavelength. For light to propagate around the circumference of the cavity, its wavelength
must be the circumference divided by an integer. This propagating light, at a certain wavelength, constitutes one mode of the cavity. However, due to a sphere’s complete symmetry, extraneous modes
appear prohibitively close together in frequency-space. The result is a line spectrum which cannot be effectively filtered for a desired frequency/wavelength, in this case 1550 nanometers. Oblating
the spherical cavity to a spheroidal geometry, however, gives the light a preferred axis to propagate along, resulting in the suppression of extraneous modes and the spacing of remaining modes. The
spaced modes may then be effectively filtered.
Publisher
Cornell Center for Materials Research
Date
2007-08-29
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Additional Notes
Support for the CCMR is provided through the NSF Grant DMR 0520404, part of the NSF MRSEC Program. Additional support is provided by Cornell University, the State of New York, and
by industrial sources.
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