Develop-Free Solgel Fabrication of Low-Loss Embedded Channel Waveguide Array

We report on the fabrication of a 4-channel embedded waveguide array by a develop-free solgel process, adopted for the first time in waveguide fabrication to improve the sidewall roughness and simplify the fabrication procedures. A kind of novel hybrid HfO2/SiO2 solgel material, which can be used to form a crack-free thick film by a single spin-coating, was prepared to construct waveguide core and cladding, whose refractive index can be accurately set by adjusting ultraviolet (UV) exposure time. The average propagation losses of the fabricated single-mode channel waveguides were measured as low as 0.19 +/- 0.02 dB/cm and 0.22 +/- 0.03 dB/cm at a wavelength of 1.55 mu m for TE and TM polarizations, respectively.