Erbium-doped glass-ridge waveguides fabricated with a collimated magnetron sputter deposition process

We report a new fabrication process for Er-doped glass ridge waveguides. The process does not require etching of an Er- doped film in defining the lateral dimension of a waveguide, but involves a lift-off process using polyimide as a sacrificial layer. An Er-doped soda-lime silicate glass film (1.5 micrometer thick) was deposited at 350 degrees Celsius using a collimated sputtering technique. Conventional sputtering techniques have been known to be incompatible with a lift-off process. The collimated sputtering, however, allowed us easy lift-off of Er-doped films, and produced well-defined ridges with smooth surface profiles as confirmed by scanning electron microscope analysis. Guided mode profiles were measured at 1.3 micrometer wavelength and compared with the simulation results.