Coefficient determination related to optical gain in erbium-doped silicon-rich silicon oxide waveguide amplifier

Abstract

Gain-determining coefficients in Er-doped, nanocrystal-Si $\mathrm{(nc-}\mathrm{Si})$ sensitized silica waveguide amplifiers are investigated. Single-mode, Er-doped silica waveguides with $\mathrm{nc-}\mathrm{Si}$ embedded in them were prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition of Er-doped $\mathrm{a-}{\mathrm{Si:O}}_x$ $\text{(x<2)}$ followed by a high-temperature anneal to precipitate $\mathrm{nc-}\mathrm{Si}.$ Exciting the Er ions via $\mathrm{nc-}\mathrm{Si}$ by pumping the waveguide from the top with the 477 nm line of an Ar laser resulted in an enhancement of the transmitted 1535 nm signal of up to 14 dB/cm, indicating a possible net gain of up to 7 dB/cm. From the dependence of the signal enhancement upon the pump power, an emission cross section of ${\text{2×10}}^{\text{−19}}\hspace{0.5em}{\mathrm{cm}}^2$ at 1535 nm and an effective excitation cross section of ${\text{⩾10}}^{\text{−17}}\hspace{0.5em}{\mathrm{cm}}^2$ at 477 nm is obtained.