Radially-Poled Stoichiometric Lithium Tantalate Microresonators for Nonlinear-Optical Applications

Whispering gallery-mode microresonators guide light by total internal reflection and exhibit exceptionally high quality factors and small mode volumes. If such a microresonator is fabricated from a nonlinear-optical material, one can benefit from these properties for efficient optical frequency conversion. One of the well-known second-order nonlinear-optical materials for these microresonators is periodically-poled lithium niobate (PPLN) because of its high second-order susceptibility and wide transmission window. Thus PPLN-based whispering gallery-mode microresonators are efficient platforms for higher-harmonic generation of ultraviolet light using a near-infrared pump source in the telecom range [1], for low-input-power optical parametric oscillation [2] and for frequency comb up- and down-conversion from the near-infrared region to the visible, ultraviolet and mid-infrared regions [3].