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Updated: May 27, 2026

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Continuous-wave ultraviolet emission through fourth-harmonic generation in a whispering-gallery resonator
Jeremy Moore1, Matthew Tomes, Tal Carmon
1Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, 1301 Beal Ave, Ann Arbor, Michigan 48109, USA.
Abstract:
We experimentally demonstrate continuous-wave ultraviolet emission through forth-harmonic generation in a millimeter-scale lithium niobate whispering-gallery resonator pumped with a telecommunication-compatible infrared source. The whispering-gallery resonator provides four spectral lines at ultraviolet, visible, near-infrared and infrared, which are equally spaced in frequency via the cascaded-harmonic process and span a 2-octave frequency band. Our technique relies on a variable crystal poling and high transverse order of the modes for phase-matching and a resonator quality factor of over 10(7) to allow cascaded-harmonic generation up to the fourth-harmonic at input pump powers as low as 200 mW. The compact size of the whispering gallery resonator pumped at telecommunication-compatible infrared wavelengths and the low pump power requirement make our device a promising ultraviolet light source for information storage, microscopy, and chemical analysis.
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