Silicon-erbium ytterbium silicate nanowire waveguides with optimized optical gain
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Single-crystal erbium silicate nanowires have attracted considerable attention because of their high optical gain. In this work, we report the controlled synthesis of silicon-erbium ytterbium silicate core-shell nanowires and fine-tuning the erbium mole fraction in the shell from x = 0:3 to x = 1:0, which corresponds to changing the erbium concentration from 4:8 × 1021 to 1:6 × 1022 cm-3. By controlling and properly optimizing the composition of erbium and ytterbium in the nanowires, we can effectively suppress upconversion photoluminescence while simultaneously enhancing near-infrared emission. The composition-optimized nanowires have very long photoluminescence lifetimes and large emission cross-sections, which contribute to the high optical gain that we observed. We suspended these concentration-optimized nanowires in the air to measure and analyze their propagation loss and optical gain in the near-infrared communication band. Through systematic measurements using wires with different core sizes, we obtained a maximum net gain of 20±8 dB·mm-1, which occurs at a wavelength of 1534 nm, for a nanowire with a diameter of 600 nm and a silicon core diameter of 300 nm.
Keywordserbium ytterbium silicate nanowire erbium concentration gain
The authors are grateful to the National Natural Science Foundation of China (Grant Nos. 11374092, 61474040, 61574054, 61635001, and 61505051), the National Basic Research Program of China (Grant No. 2012CB933703), and the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province, the Hunan Provincial Science and Technology Department (Grant Nos. 2014FJ2001 and 2014GK3015).
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