Double V-groove ridge waveguides on a silicon substrate

A new design for fabricating low-loss ridge waveguides by anisotropically etching two parallel V-grooves on a silicon substrate is proposed and demonstrated. Polymethyl methacrylate is used as the waveguide medium, with silicon dioxide and air as the lower and upper cladding, respectively. Because of the smooth sidewalls of the ridge structure, transverse confinement within the double V-groove ridge waveguide, with scattering losses of ~ 1.0 dB/cm are observed.