A communications system comprising: a network comprising carbon nanotubes; and a number of devices configured to exchange information; wherein each of the nanotubes comprises: a number of layers of carbon forming a wall of the nanotube, wherein the number of layers of carbon has a number of optical properties configured to propagate an optical signal and a number of electrical properties configured to conduct an electrical signal, the information being transmitted using the optical signal and power being transmitted using the electrical signal, and an insulating sheath configured to cover an outer surface of the wall of the nanotube, wherein the optical signal propagates within a channel in the nanotube, and wherein the electrical signal propagates along the wall of the nanotube; wherein one of the devices comprises: at least one of a receiver and a transmitter; and a power supply, wherein the power supply includes a magnetic field generator configured to generate a voltage difference between a first side and a second side of the nanotube when the electrical signal is received, and wherein the at least one of the receiver and the transmitter is configured to operate using the voltage difference. a network comprising carbon nanotubes; and a number of devices configured to exchange information; wherein each of the nanotubes comprises: a number of layers of carbon forming a wall of the nanotube, wherein the number of layers of carbon has a number of optical properties configured to propagate an optical signal and a number of electrical properties configured to conduct an electrical signal, the information being transmitted using the optical signal and power being transmitted using the electrical signal, and an insulating sheath configured to cover an outer surface of the wall of the nanotube, wherein the optical signal propagates within a channel in the nanotube, and wherein the electrical signal propagates along the wall of the nanotube; a number of layers of carbon forming a wall of the nanotube, wherein the number of layers of carbon has a number of optical properties configured to propagate an optical signal and a number of electrical properties configured to conduct an electrical signal, the information being transmitted using the optical signal and power being transmitted using the electrical signal, and an insulating sheath configured to cover an outer surface of the wall of the nanotube, wherein the optical signal propagates within a channel in the nanotube, and wherein the electrical signal propagates along the wall of the nanotube; wherein one of the devices comprises: at least one of a receiver and a transmitter; and a power supply, wherein the power supply includes a magnetic field generator configured to generate a voltage difference between a first side and a second side of the nanotube when the electrical signal is received, and wherein the at least one of the receiver and the transmitter is configured to operate using the voltage difference. at least one of a receiver and a transmitter; and a power supply, wherein the power supply includes a magnetic field generator configured to generate a voltage difference between a first side and a second side of the nanotube when the electrical signal is received, and wherein the at least one of the receiver and the transmitter is configured to operate using the voltage difference.