A team of researchers has developed a model that calculates how to create light rulers—known in science speak as frequency combs—from a nearly single frequency of light using graphene. Graphene’s conductivity varies with time when responding to electromagnetic pulses, opening up the possibility to manipulate the pulses and create highly tunable light rulers. The team showed if a beam of light is transmitted through graphene while tweaking the material’s conductivity (how much electricity the material can transmit) it creates a spectrum of light with evenly distributed peaks that function like marks on a ruler. The main advantage of this approach is its enhanced tunability, granting scientists the ability to generate a wide range of light rulers, particularly at the terahertz frequency (which lies just outside the visible light range near infrared). While in principle the analysis is valid for the entire frequency spectrum, the implementation of the method for the terahertz band is particularly intriguing, as it very difficult to achieve combs in this range and has promising applications in spectroscopy.
Tunable Terahertz Frequency Comb Generation Using Time-Dependent Graphene Sheets