Research Highlights

• Subject Categories:
  • Materials
  • Physics

Published online: 15 July 2009 | doi:10.1038/nchina.2009.144

Nanodevices: Ring cavity

Felix Cheung

Introduction

© (2009) ACS

Semiconductor nanowires are versatile building blocks for the assembly of nanoscale photonic devices, and scientists have recently begun exploiting the nanowires as waveguides for light or as optical cavities for lasers. Lun Dai, Guogang Qin and co-workers at Peking University in Beijing¹ have now put semiconductor nanowires to another use — for building 'ring cavities', which are the basis for all optical switches and modulators.

The researchers used a scanning electron microscope to bend a cadmium sulphide nanowire into a micrometre-sized ring (see top image), within which light can travel in two counter-propagating directions. They illuminated both directions by exciting the body of the ring with a focussed laser beam; certain wavelengths of light were reinforced while most wavelengths were cancelled out.

The researchers placed a straight nanowire by the side of the ring to couple light out from the cavity (see bottom image). They found that the light spectrum obtained from the nanowire–ring setup was different to that obtained from a straight nanowire, indicating that the ring cavity had served as a wavelength modulator. The researchers believe their ring cavity has potential applications in photonic integrated circuits.

The authors of this work are from:
State Key Lab for Mesoscopic Physics and School of Physics, Peking University, Beijing, China; Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing, China; HORIBA Jobin Yvon Beijing Representative Office, Beijing, China.

Reference

1. Ma, R. M. et al. Light coupling and modulation in coupled nanowire ring–Fabry-Pérot cavity. Nano Lett. doi:10.1021/nl901190v (2009). | Article |