Asymmetric light propagation in composition-graded semiconductor nanowires
J. Xu, X.Zhuang, P. Guo, W. Huang, W. Hu, Q. Zhang, Q. Wan, X. Zhu, Z. Yang, L. Tong, X. Duan, and A. Pan
Sci. Rep. 2, 820 (2012)
Asymmetric light propagation is crucial to the development of optical-based functional components in nanophotonics. Diverse configurations and structures have been proposed to allow asymmetrical propagation of photonic signal, but on-chip integration is difficult to achieve due to their complex structure and/or relatively large footprint. Here we report the first design and realization of asymmetric light propagation in single semiconductor nanowires with a composition gradient along the length. We show the asymmetric nanowire waveguides can be synthesized using a simple thermal evaporation and vapor transport approach without involving complicated and costly fabrication processes. Our studies demonstrate the asymmetric nanowire waveguides offer some significant advantages over previous designs, including ultra-low operation power, tunable working wavelength and nanoscale footprint, making them attractive building blocks for integrated photonic circuits.