*Article* **Optical-Cavity-Induced Current**

**Garret Moddel \*, Ayendra Weerakkody, David Doroski and Dylan Bartusiak**

Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309-0425, USA; Don.Weerakkody@Colorado.EDU (A.W.); doroski@Colorado.EDU (D.D.); Dylan.Bartusiak@colorado.edu (D.B.)

**\*** Correspondence: moddel@colorado.edu

**Abstract:** The formation of a submicron optical cavity on one side of a metal–insulator–metal (MIM) tunneling device induces a measurable electrical current between the two metal layers with no applied voltage. Reducing the cavity thickness increases the measured current. Eight types of tests were carried out to determine whether the output could be due to experimental artifacts. All gave negative results, supporting the conclusion that the observed electrical output is genuinely produced by the device. We interpret the results as being due to the suppression of vacuum optical modes by the optical cavity on one side of the MIM device, which upsets a balance in the injection of electrons excited by zero-point fluctuations. This interpretation is in accord with observed changes in the electrical output as other device parameters are varied. A feature of the MIM devices is their femtosecond-fast transport and scattering times for hot charge carriers. The fast capture in these devices is consistent with a model in which an energy Δ*E* may be accessed from zero-point fluctuations for a time Δ*t*, following a Δ*E*Δ*t* uncertainty-principle-like relation governing the process.

**Keywords:** MIM diode; metal–insulator–metal diode; photoinjection; internal photoemission; vacuum fluctuations; Casimir effect; zero-point fluctuations; geometrical asymmetry
