With the advent of new applications such as social media, online medical records, cloud computing there is an astronomical increase in the data that is transmitted over the Internet and within the data centers. The only viable technology to transmit such vast amounts of information on demand is the fiber optics technology. This relies on transmitting optical radiation through optical fiber. However information is almost always available in electrical form. Transmitting electrical information over the optical fiber requires optical modulators. Optical modulator imposes electrical information on the optical radiation which transports electrical information over the optical fiber. Optical modulators are needed in large quantities and are desired to be very compact, low power consuming and low cost. Furthermore their technology should allow integration with other devices to form high functionality microchips. This proposal investigates the possibility of such modulators in a novel material called graphene. Graphene is an arrangement of mono layer thick carbon atoms. Therefore the proposed effort has the potential to benefit the society and make a significant contribution to quality of life through lower cost, higher performance data transmission using fiber optics.
This proposal introduces a high risk and high reward approach for optical modulators. This is based on unique electro-optic properties of graphene. Commonly used theoretical formulas that describe conductivity of graphene suggest huge changes in real and imaginary parts of graphene dielectric constant when Fermi level in graphene is changed. This suggests very compact and efficient optical modulation. In particular using two graphene sheets separated by a thin dielectric can be used to generate very large effective index changes in a very compact dielectric waveguide. Modeling based on this theoretical analysis indicates modulator performance significantly better than the state of the art even without significant optimization. The rewards could be much bigger with careful optimization and design. However, there are significant unknowns that may limit these predictions. This proposal investigates the veracity of these ideas to see if graphene can be utilized for superior modulators that will be the work horse of next generation datacom and telecom applications. An experimental study will be performed to verify the predictions of this approach. Basic modulator structures will be fabricated and characterized to quantify effective index changes induced in graphene through external voltages. The results of this study are expected to be a fundamental contribution to basic science that describes graphene.
