Raman Signal Enhancement in Graphene via a Micro-Ring Resonator

Micro-ring resonators (MRR) "trap" incoming light, and therefore, have been shown to achieve extremely high local intensities of light. Thus, they can be used to facilitate highly non-linear optical signals. By embedding materials that host non-linear optical processes inside the MRR, we expect to observe an enhancement in the strength of the non-linear optical signal. Here, we demonstrate this concept by extracting the Raman signature of graphene that is placed inside a micro-ring resonator(MRR). We use a highly doped silica MRR which features an optical bus waveguide coupled to a looped(ring) tuned to 1550nm wavelength. We are able to observe the Raman signal of the embedded graphene at the 1550nm excitation wavelength. In addition, we were able to observe the Raman signal with an excitation wavelength of 516nm via third harmonic generation inside the MRR. This work demonstrates the feasibility of the MRR as a non-linear signal enhancer.