Micro-Ring Resonator Devices Prototyped on Optical Fiber Tapers by Multi-Photon Lithography

Multi-photon lithography -a powerful laser nanoscale additive-manufacturing method- is employed for structuring micro-ring traveling-wave resonators onto micrometric diameter, optical fiber tapers. These weakly guided, micro-ring resonating structures achieve light circulation with Q-factors of the order of ∼2.0 × 103, for typical diameters of tens of micrometers, in the spectral band of 1550 nm. The parametrization of the fabrication process, the characterization of these structures in TE and TM polarization, and the numerical simulation of their spectral performance is presented and analyzed. Moreover, these micro-ring resonators are exemplified into the demonstration of an ethanol vapor sensor, readily achieving detectivities of 0.5 ppm, based on reversible physisorption effects. Our demonstration aims at developing a new type of photonic platforms, based on a versatile, laser based prototyping approach onto micrometric size, optical fiber tapers, while exhibiting unique guiding and modal interaction characteristics, for departing the laboratory bench, while being implemented into diverse types of sensing and actuating devices.