Resonant Optical Wave Power Control Devices and Methods

CIT No. 
Date Issued: 
October 14, 2003
Patent Number: 
Google Patents: 
Kerry Vahala
Amnon Yariv
An optical wave power control device and method enables signal control, such as modulation and switching, to be effected within an uninterrupted propagation element, e.g. an optical fiber or planar waveguide. The propagation element is configured such that a portion of its wave guided power encompasses the exterior surface of the element, intercepting the periphery of an adjacent high Q volumetric resonator. Power of a chosen resonant wavelength is coupled into the resonator, where it circulates with very low loss in accordance with the principles of a whispering gallery mode device, and returns energy to the propagation element. By introducing loss within the resonator, the propagated power can be varied between substantially full and substantially zero amplitudes. Loss factors can be maintained such that the resonator is overcoupled, i.e. parasitic losses are less than coupling losses, and a critical coupling condition exists in which a small swing in the control effect causes a disproportionate change in the optical output signal.