Improvement of efficient coupling and optical resonances by using taper-waveguides coupled to cascade of UV210 polymer micro-resonators

Rigoberto Castro-Beltran (1) , Nolwenn Huby (1) , Goulc'Hen Loas (1) , Hervé Lhermite (2) , David Pluchon (1) , Bruno Bêche (3, 1)

1 IPR - Institut de Physique de Rennes
2 IETR - Institut d'Électronique et des Technologies du numéRique
3 IUF - Institut universitaire de France

In this paper, we report the overall design, fabrication and optical characterization of single and multiple resonant micro-structures patterned on the UV210 polymer and shaped by adequate deep-UV lithography procedures. Various families of ring and racetrack forms are investigated with different geometrical dimensions linked to the micro-resonators and the specific taper-waveguides and gaps allowing the optimized coupling. Well defined photonic structures families in the sub-micrometer range obtained by this deep UV-light process are clearly confirmed through scanning electron microscopy. In order to evaluate and quantify the efficiency of the sub-micrometer coupling, the recirculation of the light and the quality of the optical resonance aspects, a global study including top view intensity imaging, spectral measurements and Fast Fourier Transform analysis is performed for all these devices based on single and multiple family resonators. The experimental TE-mode resonance transmissions reveal a complete agreement with the period of the theoretically expected resonances. A maximum value of the quality factor Q = 3.5 x 10^3 at 1035 nm with a 3.2 times higher resonance contrast is assessed for cascade of triple micro-resonators respect to the photonic devices based on only one micro-resonator. In addition, these UV210 circuits made of specific tapers coupling to cascade loops act directly on the improvement of the evanescent coupling and resonances in terms of quality factor and extinction rate, by selecting successively and more precisely the optical mode resonance. All these designs and low cost technological reproducible steps, and furthermore the devices and protocol measurements are markedly suitable for mass fabrication and metrology applications.

Domaines: Optique / photonique; Matériaux; Micro et nanotechnologies/Microélectronique

Rigoberto Castro-Beltran, Nolwenn Huby, Goulc'Hen Loas, Hervé Lhermite, David Pluchon, et al.. Improvement of efficient coupling and optical resonances by using taper-waveguides coupled to cascade of UV210 polymer micro-resonators. Journal of Micromechanics and Microengineering, 2014, 24, pp.125006. ⟨10.1088/0960-1317/24/12/125006⟩. ⟨hal-01082273v2⟩