We use a Fourier-space imaging technique relying on outcoupling grating probes to study the coupled mode interaction and dispersion properties of guided modes in silicon-on-insulator codirectional couplers. Our approach allows us to measure the mode splitting inherent to coupled systems, determine the mode symmetry, and locally probe the coupling length with an accuracy of +/- 50 nm. A systematic study of directional couplers with different waveguide widths, coupling gaps, and e-beam exposure doses is reported in order to verify the results across a wider parameter space. (C) 2008 American Institute of Physics.
Laurent Villard, Stephan Brunner, Alberto Bottino, Moahan Murugappan
Till Junge, Ali Falsafi, Martin Ladecký
Martin Vetterli, Paul Hurley, Eric Bezzam, Sepand Kashani, Matthieu Martin Jean-André Simeoni