Theory of the optical-rectification effect in metallic thin films with periodic modulation

Abstract

We conducted theoretical and numerical investigations of the optical rectification (OR) effect in metallic structures with periodic modulation. A new formulation of the OR effect is presented, and the mechanism by which the OR effect is generated, which has been a controversial issue in previous studies, is clarified. We reveal that the OR effect is strongly enhanced by a combination of spatial variation of the metallic structure and local electric field enhancement. Our theory was numerically evaluated and agreed fairly well with experiment.

Plasmon drag effect with sharp polarity switching

“…Possible mechanisms of the voltage generation in nanofeatures may include thermoelectric effects [39], nonlinearity and asymmetry of electron motion [3,40] or charging due to high field gradients, which can be described theoretically [21] in terms of the effective striction force. The striction force is conservative [22]; it is expected to affect only the electron density distribution and not result in the total photocurrent across the sample even in the case of a highly asymmetric intensity distribution around a nanofeature.…”

Photoinduced electric effects in various plasmonic materials

“…Later, it was found in various experiments, that the plasmonic pressure mechanism does not provide a full explanation of several experimental findings, such as a sharp switching in the polarity of photocurrents in profile-modulated films with a high profile-modulation height upon a small variation in the incidence angle [24], or polarity switching in flat films when pumping air out of the chamber containing the film [30]. The effects of surface morphology [24,31], surface charges [30], or the nonlinearity of electron motion [18,28] are suggested in literature as important factors, which may play an additional or, possibly, a major role in the effect.…”

“…Understanding the mechanisms of such effects is important for both fundamental physics and applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Significant DC electrical effects, electric potentials, and photocurrents associated with plasmonic excitations [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] are among these effects. Electric potentials reported in [21] show different signs for illumination at wavelengths below or above the localized surface plasmon resonance and are explained with a thermodynamic approach [22].…”

Magnetically dependent plasmon drag in permalloy structures

“…In our work, we look for the signature of this process in photocurrent behavior and explore possible magneto-dependent response to plasmon excitation in systems, which combine plasmonic and magnetic properties. Strong enhancement of photocurrents in gold and silver structures observed at SPP resonance (plasmon drag effect) [13][14][15][16][17][18] is commonly discussed in terms of linear momentum exchange between light and matter [19][20][21], however, other factors (such as surface charges or highly nonlinear electron motion) can play a significant role [15,21,22]. If SAM transfer creates spin polarization, the overall picture of the photoinduced electric effects may be very different [23] from that in a purely non-magnetic case, bringing a new dimension to this research area.…”