  An ultra-compact one-dimensional topological photonic crystal (1D-TPC) is
designed in a single mode silicon bus-waveguide to generate Fano resonance
lineshape. The Fano resonance comes from the interference between the discrete
topological boundary state of the 1D-TPC and the continuum high-order leaky
mode of the bus-waveguide. Standalone asymmetric Fano resonance lineshapes are
obtained experimentally in the waveguide transmission spectrum with a maximum
extinction ratio of 33 dB and a slope ratio of 10 dB/nm over a broadband flat
background.
