Advanced Coupling Technologies for Planar and Strip Waveguides
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Grating couplers are frequently used to couple free-space beams to thin-film waveguides on planar substrates. We use finite element method (FEM) simulations to analyze the effect of experimental parameters on coupling efficiency and to optimize the grating design for specific applications. Grating fabrication is demonstrated by direct laser ablation using a UV-laser processing system at 157 nm wavelength. As a novel coupling technique, we propose to use external gratings fabricated on the end face of a collimating micro lens or immediately on the exit face of an optical fiber to couple light from a single-mode fiber directly to planar or strip waveguides. FEM simulations and experimental results show that the new technique can provide similar coupling efficiencies as common internal grating couplers. The external couplers can be repeatedly reused and eliminate the need for conventional internal grating couplers, which induce a major part of the production costs and impose certain restrictions on the waveguide devices.
KeywordsCoupling Efficiency Transversal Electric Evanescent Field Total Internal Reflection Fluorescence Grating Coupler
The authors thank A. Selle for conducting some parts of the FEM calculations and acknowledge financial support by the German Ministry of Economics and Technology.
- 1.S. Sinzinger, J. Jahns, Microoptics (Wiley-VCH, Weinheim, 1999)Google Scholar
- 3.B.E.A. Saleh, M.C. Teich, Fundamentals of Photonics, 2nd edn. (Wiley, Hoboken, 2007)Google Scholar
- 4.F. de Fornel, Evanescent Waves: From Newtonian Optics to Atomic Optics. Optical Sciences, vol. 73 (Springer, Berlin, 2001)Google Scholar