Quantum Electrostatic Model for Optical Properties of Nanoscale Gold Films

Qian, Haoliang; Xiao, Yuzhe; Lepage, Dominic; Chen, Li; Liu, Zhaowei

doi:10.1515/nanoph-2015-0022

Cited by 23 publications

(28 citation statements)

References 36 publications

(43 reference statements)

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“…To fully understand the nonlinear optical properties of the MQW, a quantum electrostatic model 31 that is based on the self-consistent solution from Schrödinger and Poisson equations is used to calculate the eigen-state wave functions and eigen energies. As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Giant Kerr response of ultrathin gold films from quantum size effect

2016

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With the size of plasmonic devices entering into the nanoscale region, the impact of quantum physics needs to be considered. In the past, the quantum size effect on linear material properties has been studied extensively. However, the nonlinear aspects have not been explored much so far. On the other hand, much effort has been put into the field of integrated nonlinear optics and a medium with large nonlinearity is desirable. Here we study the optical nonlinear properties of a nanometre scale gold quantum well by using the z-scan method and nonlinear spectrum broadening technique. The quantum size effect results in a giant optical Kerr susceptibility, which is four orders of magnitude higher than the intrinsic value of bulk gold and several orders larger than traditional nonlinear media. Such high nonlinearity enables efficient nonlinear interaction within a microscopic footprint, making quantum metallic films a promising candidate for integrated nonlinear optical applications.

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Section: Resultsmentioning

confidence: 99%

Giant Kerr response of ultrathin gold films from quantum size effect

2016

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“…For this purpose, the high-quality gold films of various thicknesses (ranging from ~20 to 200 nm) were deposited on silicon substrate by use of conventional e-beam evaporation (EBE) technique. Regarding the films thickness range (which we chose to work with), it is important to note that once the film thickness is less than 20 nm one can get island or highly roughened film surfaces and quantum confinement effects need to be considered [20,21]. At the same time, the films with a thickness of more than 200 nm are guaranteed to behave as a bulk metal.…”

Section: Introductionmentioning

confidence: 99%

Optical constants and structural properties of thin gold films

Yakubovsky¹,

Arsenin²,

Stebunov³

et al. 2017

Opt. Express

309

153

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We report a comprehensive experimental study of optical and electrical properties of thin polycrystalline gold films in a wide range of film thicknesses (from 20 to 200 nm). Our experimental results are supported by theoretical calculations based on the measured morphology of the fabricated gold films. We demonstrate that the dielectric function of the metal is determined by its structural morphology. Although the fabrication process can be absolutely the same for different films, the dielectric function can strongly depend on the film thickness. Our studies show that the imaginary part of the dielectric function of gold, which is responsible for optical losses, rapidly increases as the film thickness decreases for thicknesses below 80 nm. At the same time, we do not observe a noticeable dependence of optical constants on the film thickness for thicker samples. These findings establish design rules for thin-film plasmonic and nanophotonic devices.

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“…In these plasmonic systems, due to the plasma screening effect, [ 9 ] it is the screened field, not the incident field, to which the electrons respond. [ 10 ] As a result, the dielectric function of MQWs is assumed to be scalar, [ 10–15 ] meaning that there are no polarization selection rules applicable to their linear optical properties. It was not until very recently, however, that the optical nonlinearities of MQWs have been experimentally explored, enabled by the success in fabrication of ultrathin continuous metallic films on top of a dielectric substrate.…”

Section: Introductionmentioning

confidence: 99%

“…It was not until very recently, however, that the optical nonlinearities of MQWs have been experimentally explored, enabled by the success in fabrication of ultrathin continuous metallic films on top of a dielectric substrate. [ 13,16,17 ] Surprisingly, ISBT peaks, the signature of the quantum size effect in QWs, have been observed in the nonlinear coefficient spectra of these MQWs [ 16,17 ] ; the manifestation of the ISBTs is an extraordinary enhancement of these optical nonlinearities which are several orders of magnitude larger than those of traditional nonlinear materials at visible/near‐infrared (NIR) frequencies. However, no systematic study of the ISBT selection rules for optical nonlinearities in MQWs has been made.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Nonlinear Optical Selection Rules in Metallic Quantum Wells

Qian

Liu

2020

Adv Funct Materials

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Intersubband transitions (ISBTs) in conduction-band quantum wells (QWs) have attracted tremendous attention for their high technological potential, ranging from quantum cascade lasers, quantum well infrared photodetectors, to various nonlinear optical elements. One of the main characteristics of using the ISBTs is their polarization selection rule, which forbids a normalincidence geometry. Here, it is shown that the ISBT selection rule is not strict on optical nonlinearities in metallic QWs (MQWs). The nonlinear process of second harmonic generation nearly follows the selection rule, while the optical Kerr nonlinear process severely deviates from it. The anomalous optical selection rules result from the non-negligible ultrafast electron-electron scattering in these plasmonic systems, and a coupled mode theory is provided to get a physical grasp of the problem. The flexible selection rule in MQWs could bring drastic improvements in efficiency and diversity of ISBT-based devices.

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Quantum Electrostatic Model for Optical Properties of Nanoscale Gold Films

Cited by 23 publications

References 36 publications

Giant Kerr response of ultrathin gold films from quantum size effect

Giant Kerr response of ultrathin gold films from quantum size effect

Optical constants and structural properties of thin gold films

Anomalous Nonlinear Optical Selection Rules in Metallic Quantum Wells

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