Quasistatic optical modulation of Fowler–Nordheim field emission

We investigate the quasistatic modulation of Fowler–Nordheim-type field emission by an external optical field. When the characteristic tunneling time is much shorter than the optical period, the emission process is governed by the instantaneous local electric field, and the tunneling barrier can be modulated without direct photon absorption. Even a moderate optical field produces an exponential variation in the emission current due to the strong sensitivity of tunneling to the local field amplitude. This effect is further enhanced in nanoscale emitters by local field concentration. Order-of-magnitude estimates indicate that realistic parameters can yield substantial modulation of the emission current. The proposed mechanism provides a contribution to optical control of electron emission and may be relevant for ultrafast electron sources and nanoscale vacuum electronic devices.