Graphene is a two dimensional material with unique optical properties, which is of great significance in silicon photonics. One important issue is the optical loss induced by graphene when graphene is transferred onto the silicon devices. The traditional method to estimate the linear absorption coefficient is the ‘cut-back’ method in which multiple waveguides with different lengths of graphene are fabricated in one process. This method can never preciously measure the linear absorption coefficient (LAC) of in-plane graphene
Prof. Yi Wang’s team of ANPI, Wuhan National Laboratory for Optoelectronics, has overcome a series of technique problems，realizing the patterning of graphene on silicon optoelectronics successfully. We experimentally propose a new method to determine the LAC of graphene. And we also find that the silicon microring resonator can enhance the absorption of graphene. Our research is of great importance for the nonlinear optical device based on silicon-graphene hybrid waveguide.
On October 10th, 2016, the investigation result entitled “Enhanced linear absorption coefficient of in-plane monolayer graphene on a silicon microring resonator” was published in “Optics Express” (vol. 24, no. 17, pp. 24105-24116, 2016). Relative work was partially supported by the National Natural Science Foundation of China (NSFC) (No. 60806016, No. 61177049) and National Basic Research Program of China (No. 2012CB922103, No. 2013CB933303).
Fig. 1. (a) SEM picture of the hybrid device; (b) Zoom-in SEM images of
the local monolayer graphene covered area; (c) Photonic crystal grating coupler used for coupling light into and out of the device.
Fig. 2. (a) Cross section of the hybrid device; (b) Experimental and simulated LAC of in-plane monolayer graphene as a function of the five resonant wavelengths of the fabricated device.