Proton beam writing of erbium-doped waveguide amplifiers

Buried channel waveguide amplifiers in Er3+-Yb3+ co-doped phosphate glasses were fabricated by proton beam writing using a focused sub-micron beam of 2.0 MeV protons with a fluence ranging from 0.5-6.0 × 1015 particles/cm2. The waveguides were located at a depth of ∼38 μm beneath the surface. Above a threshold fluence of 3.0 × 1015 particles/cm2, a negative refractive index change occurs, preventing any light confinement in the channel. A peak net gain of ∼1.57 dB/cm was measured for waveguides fabricated with a fluence of ∼0.9 × 1015 particles/cm2. These measurements were performed at 1.534 μm signal wavelength, with 100 mW pump power at 975 nm wavelength.