High Gain Submicrometer Optical Amplifier at Near-Infrared Communication Band
X. Wang, X. Zhuang, S. Yang, Y. Chen, Q. Zhang, X. Zhu, H. Zhou, P. Guo, J. Liang, Y. Huang, A. Pan, and X. Duan
Phys. Rev. Lett. 115, 027403 (2015)
Nanoscale near-infrared optical amplification is important but remains a challenge to achieve. Here we report a unique design of silicon and erbium silicate core-shell nanowires for high gain submicrometer optical amplification in the near-infrared communication band. The high refraction index silicon core is used to tightly confine the optical field within the submicron structures, and the single crystalline erbium-ytterbium silicates shell is used as the highly efficient gain medium. Both theoretical and experimental results show that, by systematically tuning the core diameter and shell thickness, a large portion of the optical power can be selectively confined to the erbium silicate shell gain medium to enable a low loss waveguide and high gain optical amplifier. Experimental results further demonstrate that an optimized core-shell nanowire can exhibit an excellent net gain up to 31 dB mm−1, which is more than 20 times larger than the previously reported best results on the micron-scale optical amplifiers.