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We propose and demonstrate compact, add-drop filters using cladding-modulated, sub-wavelength grating (SWG), contra-directional couplers (CDCs) on a silicon-on-insulator platform. In our device, two asymmetric SWG waveguides, integrated with periodically loaded Bragg segments along the sides of the waveguides, are used to achieve contra-directional coupling between the fundamental and next higher-order transverse electric modes of the two-SWG-waveguide system. We present results for a 286.8-μm-long CDC that has a 3 dB bandwidth of 13.4 nm at the drop-port with a low excess loss of 0.8 dB. This device also has an 11.5-nm region at the through-port over which the extinction ratio is greater than 40 dB.