Simulations of Modulation of the Current in a Field Emitter Caused by a CW or Pulsed Laser

Abstract
Solutions of the time-dependent Schrödinger equation show that the tunneling current in a field emitter may be modulated by means of a laser. The steady-state response is calculated with Floquet methods, and the transient response is determined with a product formulation that does not require the use of absorbing boundary conditions or wave packets. The steady-state response contains a series of resonances, but when the full distribution of energies in a metal is considered the resulting effect is a broad peak that is typically centered in the blue end of the visible spectrum, but may be shifted by varying the applied static field. The transient solutions show that the response of the electrons to the optical fields is delayed by the semiclassical tunneling time, which is defined as the time for traversing the inverted barrier.