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

• Published in: Journal of micromechanics and microengineering Vol. 24; no. 12; pp. 125006 - 125012
• Main Authors: Castro-Beltran, R, Huby, N, Loas, G, Lhermite, H, Pluchon, D, Bêche, B
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.12.2014; Institute of Physics
• Subjects: Cascades; Coupling; Devices; Engineering Sciences; Exact sciences and technology; Imaging; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; integrated optics; Lithography; Materials; Mechanical instruments, equipment and techniques; Micro and nanotechnologies; Microelectronics; Micromechanical devices and systems; microresonators; Optical resonance; Optics; organic compounds; Photonic; Photonics; Physics; Quality factor; Design; Patterning; Fast Fourier transforms; Photonic crystals; Ultraviolet lithography; Waveguides; Nanostructures; Microstructure; Resonators; Microelectromechanical device
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/24/12/125006

In this paper, we report the overall design, fabrication and optical characterization of single and multiple resonant micro-structures patterned on UV210 polymer and shaped by using 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  ×  103 at 1035 nm with a 3.2 times higher resonance contrast is assessed for cascade of triple micro-resonators with respect to photonic devices based on only one micro-resonator. In addition, 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 the optical mode resonance successively and more precisely. All these designs have low cost technological reproducible steps, and the devices and protocol measurements are markedly suitable for mass fabrication and metrology applications.