Fabrication of planar optical waveguides by electrical microcontact printing

This letter describes the fabrication by electrical microcontact printing (E-μCP) of planar, optical waveguides, and splitters made of poly(4-vinylphenol) doped with phloxine B. This soft-lithographic technique uses a poly(dimethylsiloxane) (PDMS) stamp coated with a thin gold film to pattern the flow of current through the film of doped polymer. The current bleaches the phloxine B, and thus creates regions of high (unbleached; waveguide core) and low (bleached; waveguide cladding) refractive index. The maximum exposure time to obtain Δn=0.025 was 90 s. This system is useful for guiding light having λ=600–1310 nm. These polymer waveguides preserve polarization, and are able to guide light around 90° corners with a minimum radius of curvature of 1.6 mm. E-μCP patterned a 1×4 optical power splitter in 10 s. This technique is potentially useful for rapid prototyping of planar and multilevel optical devices.