Quadratic Electro-Optic Effect in Metal Nanoparticles in a Transparent Dielectric Medium

Abstract

The quadratic electro-optic effect/Kerr coefficients were measured for the first time for metal nanoparticles. In particular, gold nanoparticles in glass were studied. Measurements were made using the field-induced birefringence method at a wavelength near the onset of the surface plasmon resonance. The magnitudes of the Kerr coefficients for different sizes of gold nanoparticles in glass were measured and compared with that of subnanometer size metallic particles in non-conjugated conductive polymers. The magnitude of the Kerr coefficient was found to increase rapidly (about d−3) when the diameter, d, of the nanoparticles was decreased. This is consistent with the existing theories and understanding of nonlinear optics in metal nanoparticles. The results imply a broad range of new applications of metal nanoparticles in electro-optic switching/modulation, low-cost Kerr cells and other uses in optoelectronics.

Electroabsorption in Metallic Nanoparticles within Transparent Dielectric Media

“…Comparing with doped nonconjugated conductive polymer, the increase roughly goes as d −3 , where d is the nanoparticle-diameter. This is identical to the dependence of the real part of Kerr coefficient (K) on d as reported earlier [6]. For quadratic electro-optic measurements, the magnitudes of modulations were large enough to measure for all three sizes of gold nanoparticles in glass [6].…”

“…Saturation of absorption and two-photon absorption in specific nanometallic systems have also been studied [1][2][3][4][5][6][7][8][9][10][11][12]. Very recently, we have reported quadratic electro-optic effect in metallic nanoparticles within dielectric media [6]. As our literature review has revealed no measurement of electroabsorption in metal nanoparticles has been published or known in the prior art.…”

“…The third-order susceptibilities (χ (3) ) and response times of various metallic nanoparticles in dielectric media have been measured for different diameters of nanoparticles. Saturation of absorption and two-photon absorption in specific nanometallic systems have also been studied [1][2][3][4][5][6][7][8][9][10][11][12]. Very recently, we have reported quadratic electro-optic effect in metallic nanoparticles within dielectric media [6].…”

“…For nonconjugated conductive polymers the electro-optic effect is the largest known, therefore only microns-thick samples are used for measurements. Quadratic electro-optic measurements were successfully carried out and a clear correlation between the real part of Kerr coefficient (K) and diameter of metal nanoparticles was established down to the subnanometer domain [6]. The magnitude of the real part of Kerr coefficient (K) was shown to have a~1/d 3 dependence, where d represents diameter of the metallic nanoparticle.…”

“…Nonlinear optics in metal nanoparticles within transparent dielectric media has been studied extensively [1][2][3][4][5][6][7][8][9][10][11][12][13]. In particular, third order optics using ultrashort (femtosecond) laser pulses in such metal nanoparticle systems have been widely studied and reported.…”