Er–Yb Waveguide Amplifiers in Novel Silicate Glasses

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A set of novel silicate glasses containing ZnO and co-doped with <formula formulatype="inline"><tex>${\hbox {Er}}^{3+}$</tex></formula> and <formula formulatype="inline"><tex>${\hbox {Yb}}^{3+}$</tex></formula> was designed as substrates for optical waveguide amplifiers. Characterized by exceptionally low up-conversion, minimum Er concentration quenching and high mechanical as well as chemical stability, the reported glasses can compete with phosphate-based materials typically used in the state-of-art active devices. Straight channel waveguides with propagation losses as low as 0.18 dB/cm were fabricated in these substrates using <formula formulatype="inline"><tex>${\hbox {Ag}}^{+} \Leftrightarrow {\hbox {Na}}^{+}$</tex></formula> and <formula formulatype="inline"> <tex>${\hbox {K}} ^{+} \Leftrightarrow {\hbox {Na}}^{+}$</tex></formula> thermal ion exchange. Net on-chip gain values of 6.7 dB at 1537 nm were measured and a net fiber to-fiber gain of 5 dB was achieved when pumped at 976 nm. A six-level spatially resolved numerical model of an Er–Yb co-doped active waveguide was developed to analyze and optimize the amplifier performance. Modification of the rare-earth dopant concentration and the channel waveguide geometry was proposed to increase the gain figure and improve the overall amplifier efficiency. </para>