Ultra-thin polymer optical waveguide couplers for integrated optics based on Bloch surface waves (BSWs) are presented. Desirable BSW guiding properties, such as low loss and long propagation distance, are observed. The waveguide thickness is on the order of lambda/15. At 1562 nm wavelength, a coupling length of 250 µm is found for 3 µm wide waveguides separated by 1 µm. The second-order mode is also investigated; we show that the fundamental mode can be excited by the second-order mode. The effect of variations in the waveguide width, gap, and refractive index are theoretically investigated by studying their impacts on the coupling length. Results are promising for mode division multiplexing, optical sensors, and optical communications. (C) 2014 Optical Society of America