DOCSLIB.ORG

Plasmonics for Surface Enhanced Raman Scattering: Nanoantennas for Single Molecules

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Plasmonics for Surface Enhanced Raman Scattering: Nanoantennas for Single Molecules This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. JSTQE-INV-NB-04992-2013 1 Plasmonics for Surface Enhanced Raman Scattering: Nanoantennas for Single Molecules Kenneth B. Crozier, Senior Member, IEEE, Wenqi Zhu, Dongxing Wang, Shiyun Lin, Michael D. Best, and Jon P. Camden compelling applications for plasmonics is surface enhanced Abstract— Surface enhanced Raman scattering (SERS) is Raman scattering (SERS). While the SERS phenomenon was undergoing a renaissance, spurred largely by developments in the reported some time ago [20, 21], the recent upsurge in burgeoning field of plasmonics. This paper reviews the current plasmonics has enabled exciting new capabilities. In this status and future directions in plasmonic nanostructures for paper, we first review the SERS phenomenon. We then outline SERS. We show that engineered plasmonic nanostructures enable exciting new functionalities, including beamed Raman how plasmonics and nanophotonics have enabled beamed scattering and highly reproducible chips for single molecule Raman scattering, single molecule SERS on a chip, and SERS SERS. We furthermore show that silicon photonics enables SERS with metal nanoparticles optically trapped by photonic to be performed using optically-trapped Ag nanoparticle clusters. resonators. These advances have been in part enabled by thinking about the plasmon structures as antennas [22-26]. Index Terms— Chemical and biological sensors, To understand SERS, we begin by considering the Raman nanofabrication, nanolithography, nanomaterials, nanophotonics, nanoscale devices, Raman scattering, surface process [27]. When light is scattered by a molecule (Fig. 1), plasmons (SPs). the process is generally elastic, a process is termed Rayleigh scattering. This can be modeled classically by considering the molecule to act as a dipole that oscillates at the same I. INTRODUCTION frequency as the incident electric field , with = 푝⃗ ECENT years have seen an explosion of interest in the where is the linear polarizability tensor. On the other hand, 퐿 �⃗ 퐿 �⃗ field of plasmonics, which has come to refer to the use of a molecule휈 containing atoms ( 2) 퐸will have푝⃗ 3훼� ∙ 퐸6 R 퐿 surface plasmon polaritons (SPPs) to route and manipulate vibrational훼� modes (3 5 for linear molecules). Each light on the nanoscale [1]. An exciting range of applications corresponds to a particular푁 vibrational푁 ≥ pattern, in which푁 −the have been enabled that are too diverse to fully review here, but atoms of the molecule푁 oscillate− at frequency , with measuring the oscillation amplitude and termed the normal include highly miniaturized optical devices, such as lasers [2, 푀 푘 3], waveguides [4], photodetectors [5] and modulators [6], mode coordinate. These perturbations modify th휈e molecule’s푄 biosensors [7], heat-assisted magnetic recording [8], polarizability. This can be expressed as follows: polarization elements [9-11], optical tweezers [12-18] and metamaterials [19]. We argue, however, that one of the most ( ) = (0) + + + (1) 2 휕훼�퐿 1 휕 훼�퐿 2 퐿 푘 퐿 푘 2 푘 Manuscript received August 13, 2013; revised September 8, 2013. First 휕푄푘 2 휕푄푘 훼 � 푄 훼� � �푄푘=0 푄 � �푄푘=0 푄 ⋯ published ZZ; current version published AA. This work was supported by the The perturbation caused by the vibration therefore modulates National Science Foundation (NSF, grant ECCS-0747560 and grant ECCS- 1201687), the Harvard Quantum Optics Center, and by the Center for the polarizability at frequency , meaning that the scattered Excitonics, an Energy Frontier Research Center funded by the U.S. field contains not only a component at , but also 푀 Department of Energy, Office of Science and Office of Basic Energy Sciences components at “beat” frequencies휈 and + . This under Award Number DE-SC0001088. This work was also supported by the 퐿 classical model therefore predicts the existence 휈of Stokes and UT/ORNL Joint Institute for Advanced Materials, and the U.S. Department of 퐿 푀 퐿 푀 Energy, Office of Basic Energy Sciences, under Award Number anti-Stokes Raman scattering (Fig.휈 − 휈1). The휈 model휈 has DESC0004792 (J.P.C.) and the National Science Foundation under Awards shortcomings [27], e.g. it does not correctly predict the CHE-0954297 and DMR-0906752 (M.D.B.). Fabrication work was carried out in the Harvard Center for Nanoscale Systems, which is supported by the magnitudes of the Stokes and anti-Stokes intensities, but NSF. nonetheless provides helpful insights, including the following Wenqi Zhu, Dongxing Wang, and Kenneth B. Crozier are with the School two. First, the model predicts that many of the vibrational of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 USA (emails: [email protected], [email protected], modes of molecules are Raman-inactive as, for these modes, and [email protected]). does not depend on . This is indeed the case. Second, an Shiyun Lin was with the School of Engineering and Applied Sciences, electronic resonance that results in an increase in should, Harvard University, Cambridge, MA 02138 USA. He is now with Oracle 훼�퐿 푄푘 (email: [email protected]). according to the model, result in an increase in 퐿 , and Michael D. Best and Jon P. Camden are with the Department of Chemistry, 훼� 휕훼�퐿 University of Tennessee, Knoxville, TN 37996, USA (emails: therefore also an increase in the Raman scattering.휕 푄This푘 is [email protected] and [email protected]). indeed seen in resonant Raman scattering (Fig. 1). Copyright (c) 2013 IEEE. Personal use is permitted. For any other purposes, permission must be obtained from the IEEE by emailing [email protected]. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. JSTQE-INV-NB-04992-2013 2 the mechanism of the first component (termed chemical enhancement) continues, it is generally agreed (see e.g. [33]) that it plays a far smaller role in the overall enhancement that the other two components (termed electromagnetic enhancement). The electromagnetic enhancement factor is the ratio between the Raman scattering from a molecule on 퐸퐹 an enhancing substrate to the Raman scattering that would퐸푀 be produced by the molecule in the absence of the enhancing substrate. It is commonly given by: | ( )| | ( )| = (2) | ( )| 2 | ( )| 2 퐸퐿푂퐶 휈퐿 퐸퐿푂퐶 휈푅 퐸퐹 2 2 퐸푀 퐼푁 퐿 퐼푁 푅 Fig. 1. Elastic (Rayleigh) and inelastic (Raman) scattering where and퐸 휈are the 퐸frequencies휈 of the excitation (laser) of light by a molecule (here taken as benzenethiol). and Raman scattered fields, respectively. | ( )| and 퐿 푅 | ( )휈| are the휈 magnitudes of the electric fields at the 퐿푂퐶 퐿 Raman spectroscopy is a powerful technique as it enables position of the molecule that would result for illumination퐸 휈 by 퐿푂퐶 푅 materials to be identified and characterized by their vibrational plane퐸 waves휈 with frequencies and , respectively. Note spectra, which can be thought of as “fingerprints”. In Fig. 2, that the illumination is along a specific direction, and with 퐿 푅 for example, the Raman spectrum of a 500 µm thick layer of polarization and amplitude specified휈 by휈 ( ) at the laser pure benzenethiol liquid is shown, measured using a confocal frequency and by ( ) at the Raman scattering frequency. 퐼푁 퐿 Raman system. From knowledge of the density of It is not always realized, however, that (2)퐸 is 휈only rigorously 퐼푁 푅 benzenethiol and the confocal collection volume of the Raman correct under the following퐸 휈 conditions [27]. Both illumination system (measured using method of [28, 29]), the number of and collection occur along a specific direction. The molecule molecules in the measurement was found to be ~3.7 × 10 . is assumed to have an isotropic Raman polarizability tensor When one considers the recent trend toward single molecule10 , which relates the Raman dipole = (modeling techniques in biology and chemistry [30], one realizes that this the Raman scattering) to the local field . Furthermore, (2) �푅 푅 �푅 �⃗퐿푂퐶 is a very large number. This underscores a difficulty in assume∝ s that the polarization of the푝 ⃗local∝ field∙ 퐸 is unchanged 퐿푂퐶 employing Raman spectroscopy in applications involving between laser and Raman frequencies.퐸�⃗ Lastly, (2) assumes small numbers of molecules, due to the fact that Raman polarized detection. Despite these limitations, (2) nonetheless scattering cross sections are comparatively small. in most cases provides a reasonable estimate, and emphasizes the importance of field enhancement. Metal nanoparticles are well-suited for this task, as the excitation of localized surface plasmons enables large field enhancement. This is especially true for nanoparticles separated by small gaps. In Fig. 3, for example, the intensity enhancement generated by a single gold sphere (60 nm diameter) can be seen to increase from ~24 to ~1686 times when, instead, a pair of spheres with a 5 nm gap is used. Coupling between the spheres red-shifts the resonance from λ0 = 522 nm (single sphere) to 550 nm (pair of spheres). Intensity enhancement -60 522 nm -40 Fig. 2. Measured Raman spectrum of benzenethiol liquid. -20 0 In the SERS phenomenon [20, 21], the Raman signals from y (nm) 20 40 molecules in close proximity to metallic nanostructures are 60 Au sphere (60 nm diam.) boosted significantly. The effect can be broken into three -100 -50 0 50 100 x (nm) components. First, the Raman cross section of the molecule can be modified upon its adsorption to the metal [31, 32], an -60 550 nm effect most often ascribed to charge transfer. Second, the -40 metallic nanostructure enhances the excitation electric field at -20 0 the molecule, thereby increasing the strength of the induced y (nm) 20 Raman dipole moment. Third, the metallic nanostructure 40 enables the induced Raman dipole moment to radiate more 60 5 nm gap -100 -50 0 50 100 power.
Load more

Recommended publications
  • SPASER As a Complex System: Femtosecond Dynamics Traced by Ab-Initio Simulations
    SPASER as a complex system: femtosecond dynamics traced by ab-initio simulations Item Type Conference Paper Authors Gongora, J. S. Totero; Miroshnichenko, Andrey E.; Kivshar, Yuri S.; Fratalocchi, Andrea Citation Juan Sebastian Totero Gongora ; Andrey E. Miroshnichenko ; Yuri S. Kivshar and Andrea Fratalocchi " SPASER as a complex system: femtosecond dynamics traced by ab-initio simulations ", Proc. SPIE 9746, Ultrafast Phenomena and Nanophotonics XX, 974618 (March 14, 2016); doi:10.1117/12.2212967; http:// dx.doi.org/10.1117/12.2212967 Eprint version Publisher's Version/PDF DOI 10.1117/12.2212967 Publisher SPIE-Intl Soc Optical Eng Journal Ultrafast Phenomena and Nanophotonics XX Rights Copyright 2016 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Download date 27/09/2021 00:14:10 Link to Item http://hdl.handle.net/10754/619757 SPASER as a complex system: femtosecond dynamics traced by ab-initio simulations Juan Sebastian Totero Gongoraa, Andrey E. Miroshnichenkob, Yuri S. Kivsharb, and Andrea Fratalocchia aPRIMALIGHT, King Abdullah University of Science and Technology (KAUST),Thuwal 23955-6900, Saudi Arabia bNonlinear Physics Centre, Australian National University, Canberra ACT 2601, Australia. ABSTRACT Integrating coherent light sources at the nanoscale with spasers is one of the most promising applications of plasmonics. A spaser is a nano-plasmonic counterpart of a laser, with photons replaced by surface plasmon polaritons and the resonant cavity replaced by a nanoparticle supporting localized plasmonic modes.
    [Show full text]
  • Nanolaser Arrays
    Nanophotonics 2021; 10(1): 149–169 Review Suruj S. Deka*, Sizhu Jiang, Si Hui Pan and Yeshaiahu Fainman Nanolaser arrays: toward application-driven dense integration https://doi.org/10.1515/nanoph-2020-0372 1 Introduction Received July 4, 2020; accepted September 8, 2020; published online September 29, 2020 In the quest for attaining Moore’s law-type scaling for Abstract: The past two decades have seen widespread photonics, miniaturization of components for dense efforts being directed toward the development of nano- integration is imperative [1]. One of these essential scale lasers. A plethora of studies on single such emitters nanophotonic components for future photonic inte- have helped demonstrate their advantageous character- grated circuits (PICs) is a chip-scale light source. To istics such as ultrasmall footprints, low power consump- this end, the better part of the past two decades has tion, and room-temperature operation. Leveraging seen the development of nanoscale lasers that offer knowledge about single nanolasers, the next phase of salient advantages for dense integration such as ultra- nanolaser technology will be geared toward scaling up compact footprints, low thresholds, and room- design to form arrays for important applications. In this temperature operation [2–4]. These nanolasers have review, we discuss recent progress on the development of been demonstrated based on a myriad of cavity designs such array architectures of nanolasers. We focus on and physical mechanisms some of which include pho- valuable attributes and phenomena realized due to tonic crystal nanolasers [5–8], metallo-dielectric nano- unique array designs that may help enable real-world, lasers [9–15], coaxial-metal nanolasers [16, 17], and practical applications.
    [Show full text]
  • Title All-Dielectric Nanolaser with Subnanometer Field Confinement
    FRONT MATTER Title All-Dielectric Nanolaser with Subnanometer Field Confinement Authors Hao Wu,1 Peizhen Xu,1 Xin Guo,1* Pan Wang,1 Limin Tong1,2* Affiliations 1 Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China. 2 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China. *[email protected]; [email protected]. Abstract The ability to generate a laser field with ultratight spatial confinement is important for pushing the limit of optical science and technology. Although plasmon lasers can offer sub-diffraction-confined laser fields, it is restricted by a trade-off between optical confinement and loss of free-electron oscillation in metals. We show here an all-dielectric nanolaser that can circumvent the confinement- loss trade-off, and offer a field confinement down to subnanometer level. The ultra-confined lasing field, supported by low-loss oscillation of polarized bound electrons surrounding a 1-nm-width slit in a coupled CdS nanowire pair, is manifested as the dominant peak of a TE0-like lasing mode around 520-nm wavelength, with a field confinement down to 0.23 nm and a peak-to-background ratio of ~32.7 dB. This laser may pave a way towards new regions for nanolasers and light-matter interaction. MAIN TEXT Introduction Lasers with tighter field confinement is a key to lower-dimensional light-matter interaction for applications ranging from optical microscopy, sensing, photolithography to information technology (1–3). Since the early age of laser technology, pursuing tighter field confinement in a lasing cavity mode has been a continuous effort.
    [Show full text]
  • Impact of Fundamental Temperature Fluctuations on the Frequency Stability of Metallo- Dielectric Nanolasers Sizhu Jiang ,Sihuipan , Suruj S
    IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 55, NO. 5, OCTOBER 2019 2000910 Impact of Fundamental Temperature Fluctuations on the Frequency Stability of Metallo- Dielectric Nanolasers Sizhu Jiang ,SiHuiPan , Suruj S. Deka, Cheng-Yi Fang ,ZijunChen, Yeshaiahu Fainman, Fellow, IEEE, and Abdelkrim El Amili Abstract— The capability of nanolasers to generate coherent I. INTRODUCTION light in small volume resonators has made them attractive to be implemented in future ultra-compact photonic integrated circuits. HE miniaturization of optical resonators has established However, compared to conventional lasers, nanolasers are also Tnanolasers as promising coherent light source candidates known for their broader spectral linewidths, that are usually for future integrated nanophotonics with wide applications on the order of 1 nm. While it is well known that the broad in bio-sensing [1]–[3], imaging [4]–[6], far-field beam syn- linewidths in light emitters originate from various noise sources, thesis [7] and optical interconnects [8]. The ultra-compact there has been no rigorous study on evaluating the origins of the linewidth broadening for nanolasers to date to the best of mode volume of nanolasers also enables them to exploit our knowledge. In this manuscript, we investigate the impact the cavity quantum electrodynamics (QED) effect [9]–[12]. of fundamental thermal fluctuations on the nanolaser linewidth. In these nanocavities, conspicuous Purcell enhancement helps We show that such thermal fluctuations are one of the intrinsic to dramatically increase the modulation speed and lower noise sources in a sub-wavelength metal-clad nanolaser inducing the power consumption for optical communication systems. significant linewidth broadening. We further show that with the reduction of the nanolaser’s dimensions, i.e., mode volume, However, shrinking the dimension of a nanolaser can also be and the increase of the ambient temperature, such linewidth detrimental to its performance.
    [Show full text]
  • Photonic Crystal Nanolaser Biosensor Simplifies DNA Detection 13 January 2015
    Photonic crystal nanolaser biosensor simplifies DNA detection 13 January 2015 laser emission intensity, which in turn can also be used to sense the adsorption of biomolecules. Using laser intensity to detect biomolecules is potentially less expensive than the fluorescent tagging or spectroscopy techniques typically used in biosensors because it is a simpler procedure. When the team first set out to explore photonic crystal nanolaser sensors, they weren't focusing on the intensity of the laser emission because it's sensitive to the quality of the fabricated laser and, frankly, they didn't expect it to show sensing signals. "In the beginning we focused on wavelength behavior, but quickly noticed that [the laser emission] intensity is influenced by both pH and polymers," noted Toshihiko Baba, a professor in Yokohama National University's Department of Electrical and Computer Engineering. "Our results were very reproducible and, interestingly, we found Top view of the group's nanolaser, in which the center that the behaviors of the wavelength and intensity narrow slot (horizontal line) is the main part of the are independent." sensor. The periodic holes form a photonic crystal, and although the size of the holes appears to fluctuate they've been intentionally modified so the laser's The team was surprised by these results, which emission is effectively extracted to the top. Credit: they discovered when they deposited a protective Toshihiko Baba/Yokohama National University film of thin zirconium dioxide (ZrO2) over the device using atomic layer deposition, and then tried sensing in liquids of high or low pH and liquids containing charged polymers.
    [Show full text]
  • Synthesis and SERS Application of Sio2@Au Nanoparticles
    Synthesis and SERS application of SiO2@Au nanoparticles A. Saini, T. Maurer*, I. Izquierdo Lorenzo, A. Ribeiro Santos, J. Béal, J. Goffard, D. Gérard, A. Vial and J. Plain Laboratoire de Nanotechnologie et d’Instrumentation Optique, ICD CNRS UMR n°6281, Université de Technologie de Troyes, CS 42060, 10004 Troyes, France In this letter, we report a chemical route for synthesizing SiO2@Au core-shell nanoparticles. The process includes four steps: i) preparation of the silica cores, ii) grafting gold nanoparticles over SiO2 cores, iii) priming of the silica-coated gold nanoparticles with 2 and 10 nm gold colloids and finally iv) formation of complete shell. The optical extinction spectra were experimentally measured and compared to numerical calculations in order to confirm the dimensions deduced from SEM images. Finally, the potential of such core- shell nanoparticles for biosensing was probed by means of Surface Enhanced Raman Scattering measurements and revealed higher sensitivities with much lower gold quantity of such core-shell nanoparticles compared to Au nanoparticles exhibiting similar diameters. SiO2 core-Au shell nanoparticles have attracted much attention for the past ten years due to potential applications in various fields such as cancer imaging and treatment(Loo et al., 2004), Surface-Enhanced Raman Spectroscopy (SERS) detection of molecules(Wang et al., 2006, Maurer et al., 2013), catalytic degradation of environmental pollutants(Ma et al., 2009) or even fabrication of SPASER (Surface Plasmon Amplification by Stimulated Emission of radiation) devices when the silica is dye-doped(Stockman, 2008). However, the growth of a complete gold shell around silica nanoparticles is very hard to achieve.
    [Show full text]
  • Dynamics of a Micro-VCSEL Operated in the Threshold Region Under Low-Level Optical Feedback
    1 Dynamics of a micro-VCSEL operated in the threshold region under low-level optical feedback Tao Wang, Xianghu Wang, Zhilei Deng, Jiacheng Sun, Gian Piero Puccioni, Gaofeng Wang, and Gian Luca Lippi Abstract—Semiconductor lasers are notoriously sensitive to quality, ease of integration and single-longitudinal mode emis- optical feedback, and their dynamics and coherence can be sion. In addition, they are less sensitive to optical feedback significantly modified through optical reinjection. We concentrate than their edge-emitting counterparts, rendering them more on the dynamical properties of a very small (i.e., microscale) Vertical Cavity Surface Emitting Laser (VCSEL) operated in attractive in many applications, in spite of their polariza- the low coherence region between the emission of (partially) tion sensitivity on which have focussed most of the optical coherent pulses and ending below the accepted macroscopic reinjection investigations (cf., e.g., [8], [9], [10], [11]). Our lasing threshold, with the double objective of: 1. studying the work focuses on the basic understanding of operation regimes feedback influence in a regime of very low energy consump- of very small devices which, in the future, could be used tion; 2. using the micro-VCSEL as a surrogate for nanolasers, where measurements can only be based on photon statistics. for transmissions and interconnects (e.g. datacenter applica- The experimental investigation is based on time traces and tions [12], [13]). Thus, we look at the dynamics of VCSELs radiofrequency spectra (common for macroscale devices) and due to non-polarization-selective feedback [14], [15], [16]. An correlation functions (required at the nanoscale). Comparison overview of the phenomenology observed in VCSELs with of these results confirms the ability of correlation functions to optical feedback can be found in [17].
    [Show full text]
  • Experiment and Theory: No Spasing from Core-Shell Spasers
    Experiment and Theory: No Spasing from Core-Shell Spasers Günter Kewes,1 Kathrin Höfner,2 Andreas Ott,3 Rogelio Rodriguez-Oliveros,2 Alexander Kuhlicke,1 Yan Lu,3 Matthias Ballauff,3 Kurt Busch,2, 4 and Oliver Benson1 1AG Nanooptik, Institut für Physik, Humboldt-Universität zu Berlin, Newtonstrasse 15, 12489 Berlin, Germany 2AG Theoretische Optik & Photonik, Institut für Physik, Humboldt-Universität zu Berlin, Newtonstrasse 15, 12489 Berlin, Germany 3Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Hahn-Meitner-Platz 1, 14109 Berlin, Germany 4Max-Born Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany In 2009 the smallest laser-device consisting of a single 14 nm gold sphere and a dye-doped coating was “demonstrated” [1] based on the proposal of the “spaser” from 2003 [2]. Here, we critically evaluate so far reported results on both an experimental and on a theoretical basis. Experiments: Core-shell spasers were chemically synthesized or metal nanoparticles were coated with dye-doped polymer films. Various excitation schemes were tested, yielding laser or laser-like signatures. All of them, however, were later identified to stem from sources other than spasing. Theory: A fully analytic model for spherical core-shell spasers was developed: Within this model, we drop the widely used quasi-static approximation of the electromagnetic field in favor of fully electromagnetic Mie theory. This allows for precise incorporation of realistic gain relaxation rates (quenching and cavity-to-gain coupling) that so far have only been estimated (and massively underestimated) in spaser theory. The model unravels multiple severe limitations (that exist all over the VIS) concerning the threshold-pump, the extreme gain-medium requirements and the unavoidable heat production (independent of excitation scheme).
    [Show full text]
  • Plasmon Lasers
    Plasmon Lasers Wenqi Zhu1,2, Shawn Divitt1,2, Matthew S. Davis1, 2, 3, Cheng Zhang1,2, Ting Xu4,5, Henri J. Lezec1 and Amit Agrawal1, 2* 1Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA 2Maryland NanoCenter, University of Maryland, College Park, MD 20742 USA 3Department of Electrical Engineering and Computer Science, Syracuse University, Syracuse, NY 13244 USA 4National Laboratory of Solid-State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing, China 5Collaborative Innovation Center of Advanced Microstructures, Nanjing, China Corresponding*: [email protected] Recent advancements in the ability to design, fabricate and characterize optical and optoelectronic devices at the nanometer scale have led to tremendous developments in the miniaturization of optical systems and circuits. Development of wavelength-scale optical elements that are able to efficiently generate, manipulate and detect light, along with their subsequent integration on functional devices and systems, have been one of the main focuses of ongoing research in nanophotonics. To achieve coherent light generation at the nanoscale, much of the research over the last few decades has focused on achieving lasing using high- index dielectric resonators in the form of photonic crystals or whispering gallery mode resonators. More recently, nano-lasers based on metallic resonators that sustain surface plasmons – collective electron oscillations at the interface between a metal and a dielectric – have emerged as a promising candidate. This article discusses the fundamentals of surface plasmons and the various embodiments of plasmonic resonators that serve as the building block for plasmon lasers.
    [Show full text]
  • Coupling in a Dual Metallo-Dielectric Nanolaser System
    4760 Vol. 42, No. 22 / November 15 2017 / Optics Letters Letter Coupling in a dual metallo-dielectric nanolaser system 1 1 2 1 1, SURUJ S. DEKA, SI HUI PAN, QING GU, YESHAIAHU FAINMAN, AND ABDELKRIM EL AMILI * 1Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, California 92093-0407, USA 2Department of Electrical and Computer Engineering, University of Texas at Dallas, Richardson, Texas 75080-3021, USA *Corresponding author: [email protected] Received 14 September 2017; revised 23 October 2017; accepted 24 October 2017; posted 25 October 2017 (Doc. ID 306989); published 15 November 2017 To achieve high packing density in on-chip photonic overlap and, hence, the Joule loss. Additionally, the metal integrated circuits, subwavelength scale nanolasers that should also aid in isolating the electromagnetic field inside each can operate without crosstalk are essential components. resonator from the surrounding environment. Whether the Metallo-dielectric nanolasers are especially suited for this isolation provided can prevent crosstalk between optical com- type of dense integration due to their lower Joule loss ponents for purposes of dense integration on chip, however, is and nanoscale dimensions. Although coupling between op- yet to be explored to the best of our knowledge. tical cavities when placed in proximity to one another has The observation of coupling between non-metal based been widely reported, whether the phenomenon is induced optical cavities when placed in proximity of each other has been for metal-clad cavities has not been investigated thus far. widely reported in a host of systems such as photonic crystal We demonstrate coupling between two metallo-dielectric nanocavities [12,13], photonic molecule microdisk lasers nanolasers by reducing the separation between the two [14–18], microring lasers [19,20], ridge lasers [21], and porous cavities.
    [Show full text]
  • SPASERS: Nano-Lasers Going Beyond the Diffraction Limit
    SPASERS: Nano-Lasers Going Beyond the Diffraction Limit Belinda Pacheco Literature Seminar November 9, 2017 A SPASER (Surface Plasmon Amplification by Stimulated Emission of Radiation) is a nanoscale version of a laser that has been recently theorized and experimentally demonstrated.1,2 SPASERs can be considered counterparts to the laser since they are intense, coherent light sources and require a resonator cavity-like structure with gain media. However, SPASERs dramatically differ from lasers in two ways: 1) their resonator and gain medium structures are on the nanoscale, and 2) the stimulated emission originates from overpopulation of surface plasmons in excited states, and not population inversion in the gain medium. Consequently, SPASERs can uniquely overcome the diffraction limit which is detrimental to the spatial footprint and physical size of the 3 typical laser. Based on these characteristics SPASERs (a) show tremendous prospects in fields where lasers have become limiting factors such as in ultramicroscopy, spectroscopy, ultrasensitive detection, imaging, biomedical applications, optical communications, and lab-on-a-chip devices.1,4–6 However, SPASERs have not been successfully implemented into these technologies because of their inherent lack of beam directionality and significant radiative losses.4 Despite their shortcomings, recent efforts in materials chemistry, materials science, and nano-optics (b) have provided routes for overcoming these limitations. To understand the lasing action of a SPASER, it is essential to understand the fundamentals of surface plasmons. In essence, surface plasmons (SPs) are oscillations of conduction band electrons at the interface between materials of different dielectric permittivity.7 SPs are naturally coupled to electromagnetic waves allowing them to be considered a type of boson (a polariton), thereby acting similarly to photons (i.e.
    [Show full text]
  • Open Resonator Electric Spaser Bobo Liu,† Weiren Zhu,‡ Sarath D
    Article www.acsnano.org Open Resonator Electric Spaser Bobo Liu,† Weiren Zhu,‡ Sarath D. Gunapala,§ Mark I. Stockman,# and Malin Premaratne*,† † Advanced Computing and Simulation Laboratory (AχL), Department of Electrical and Computer Systems Engineering, Monash University, Clayton, Victoria 3800, Australia ‡ Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China § Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States # Center for Nano-Optics and Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303, United States *S Supporting Information ABSTRACT: The inception of the plasmonic laser or spaser (surface plasmon amplification by stimulated emission of radiation) concept in 2003 provides a solution for overcoming the diffraction limit of electromagnetic waves in miniaturization of traditional lasers into the nanoscale. From then on, many spaser designs have been proposed. However, all existing designs use closed resonators. In this work, we use cavity quantum electrodynamics analysis to theoretically demonstrate that it is possible to design an electric spaser with an open resonator or a closed resonator with much weak feedback in the extreme quantum limit in an all-carbon platform. A carbon nanotube quantum dot plays the role of a gain element, and Coulomb blockade is observed. Graphene nanoribbons are used as the resonator, and surface plasmon polariton field distribution with quantum electrodynamics features can be observed. From an engineering perspective, our work makes preparations for integrating spasers into nanocircuits and/or photodynamic therapy applications. KEYWORDS: spaser, graphene, Coulomb blockade, carbon nanotube, plasmon n nanoplasmonics, the spaser (surface plasmon amplifica- in which, the gain medium employed a semiconductor cascade tion by stimulated emission of radiation) is a promising quantum well structure.
    [Show full text]