We propose a new type of optical transistor for a broadband amplification of THz radiation. It is
made of a graphene–superconductor hybrid, where electrons and Cooper pairs couple by Coulomb
forces. The transistor operates via the propagation of surface plasmons in both layers, and the origin
of amplification is the quantum capacitance of graphene. It leads to THz waves amplification, the
negative power absorption, and as a result, the system yields positive gain, and the hybrid acts like
an optical transistor, operating with the terahertz light. It can, in principle, amplify even a whole
spectrum of chaotic signals (or noise), that is required for numerous biological applications
