FYI: "With the placement of a sheet of graphene just one-carbon-atom-thick, the researchers transformed the originally passive device into an active one that generated microwave photonic signals and performed parametric wavelength conversion at telecommunication wavelengths."
http://phys.org/news/2012-07-ultralow-power-optical-frequency-graphene-silic on-photonic.html http://arxiv.org/pdf/1205.4333v4.pdf "They have engineered a graphene-silicon device whose optical nonlinearity enables the system parameters (such as transmittance and wavelength conversion) to change with the input power level. The researchers also were able to observe that, by optically driving the electronic and thermal response in the silicon chip, they could generate a radio frequency carrier on top of the transmitted laser beam and control its modulation with the laser intensity and color. Using different optical frequencies to tune the radio frequency, they found that the graphene-silicon hybrid chip achieved radio frequency generation with a resonant quality factor more than 50 times lower than what other scientists have achieved in silicon." Haven't read the preprint yet, but if I understand this correctly, they are claiming that a passive sheet of graphene can behave as an active (electronic) device. passive devices are those which do not require a separate power source (resistors, capacitors, inductors). Active devices, like transistors, require a power source. My guess before reading the article is that the power source here is simply a laser or some other form of energy which is getting converted (or downshifted) to some other form. Also, the statement, "achieved radio frequency generation with a resonant quality factor more than 50 times lower" must be a typo. a lower Q-factor is not something to write home about! -Mark
