Optical amplification at 1534 nm in erbium-doped zirconia waveguides

We have developed planar waveguides with net gain in erbium-doped zirconia. Ion-beam sputtering was used to deposit amorphous high-refractive-index zirconia films, which were fabricated into single-mode waveguides. By adjusting oxygen flow rates while sputtering, and annealing the films after deposition, waveguide losses were reduced to 0.45 dB/cm at 1534 nm. Erbium in the zirconia, added by co-sputtering, had a wide, 54-nm full-width at half maximum emission band centered at 1538 nm, which offers potential advantages for wideband amplification in wavelength division multiplexing systems. When pumped with 36 mW at 980 nm, a 6.5 cm long, 8.8 × 10¹⁹ cm^-3 doped waveguide produced 2.95 dB of optical amplification at 1534 nm. This was enough to overcome the waveguide loss and produce a small amount of net gain. With a higher pump power, substantial net gain appeared to be possible. These results show that wide-bandwidth erbium-doped optical amplifiers should be possible in zirconia.