Experimental analysis of the high-order harmonic components generation in few-layer graphene

In this work, the nonlinear electromagnetic response of a few-layer graphene sheet is experimentally analyzed. The few-layer graphene sheet is obtained through mechanical exfoliation from highly ordered pyrolytic graphite and embedded in a rectangular waveguide structure which is used to guide the exciting and the output signals. The nonlinear electromagnetic response of the graphene sheet is exploited to implement a frequency multiplier in which the output signal, in the 330–500 GHz frequency band, will be obtained as a high-order harmonic component of the input signal, in the 26–40 GHz frequency band. Due to the particular selection of the input and output frequency ranges, the behavior of several harmonic components, from order 9 to 17, can be characterized. The analysis will be focused on the frequency response of the graphene sheet, the influence of the input power on the output signal and the differences between the even- and odd-order harmonic components. Finally, it will be shown that the developed assembly can be used as THz signal source based on high-order frequency multiplication.