Active plasmonics: Current status

Abstract

The field of 'plasmonics' deals with the unique optical properties of metallic nanostructures, and is one of the most fascinating and fast-moving areas of photonics. It has grown rapidly in recent years, driven by parallel advances in micro-/nano-fabrication techniques, optical diagnostic systems and computational tools, as well as wide-ranging potential applications in areas from (bio)chemical sensing to solar power generation. Surface plasmon-polaritons (SPPs) -propagating bound oscillations of electrons and light at a metal surface -have attracted particular interest because, as potential information carriers for future highly-integrated devices, they offer to combine the nanoscale dimensions of today's electronic components with the speed and bandwidth of optical systems and an innate ability to interface with both.However, if such technologies are to be realized, efficient techniques for active manipulation of SPP signals will be required. Since this challenge was spelt out in a 2004 paper describing transient SPP modulation based on light-induced structural transitions in gallium [1], a wide range of material systems (including thermo-and electro-optic media, quantum dots, and photochromic molecules) have been investigated for plasmonic switching applications. We have recently demonstrated direct optical modulation of SPP propagation on the femtosecond timescale [2], while others have reported femtojoule switching energies in a field-effect plasmonic modulator [3].In this presentation I will review and compare key active plasmonic technologies, consider emerging approaches to SPP modulation -in a study based on structurally switchable chalcogenide glasses our current investigations return to the 'phase-change' roots of the active plasmonic concept, and assess future challenges and prospects for the field.With performance characteristics approaching those of current data transport and processing technologies, the race is now on to develop active plasmonic structures that are efficient, compact and compatible with existing CMOS and/or SOI fabrication processes. Indeed, in the first instance, plasmonic components are likely to augment rather than replace electronic or photonic systems, bridging the gap between the two to create powerful hybrid devices that capitalize on their respective strengths (Fig. 1). REFERENCES[1] A. V. Krasavin and N. I. Zheludev, "Active plasmonics: Controlling signals in Au/Ga waveguide using nanoscale structural transformations," Fig. 1. Artistic impression of a hybrid opto-/electro-plasmonic chip, wherein new and enhanced functionalities are achieved by close integration of photonic, electronic and plasmonic systems. 77 MJ1 (Invited) 15.30 -16.00 978-1-4244-3681-1/09/$25.00 ©2009 IEEE

Plasmonic circuits for manipulating optical information

“…In addition, it is possible to use electrical signals to induce material changes, particularly in semiconductors where the electron density, and therefore the "metallic" properties, can be altered. These are termed "active plasmonic" devices [101]. The methods for non-linear modulation of plasmons are summarized in Figure 5.…”

Photonic switching devices based on semiconductor nano-structures

“…The theoretical framework we have discussed above indicates a local enhancement of the electrical field and the nonlinear susceptibility in proportion to the factor of . A typical plasmonic cavity can reach a Q factor of a few tens and an ultra-small mode volume of 10 -2 cubic wavelength, resulting in large field enhancement that enables us to actively modulate or switch light in the vicinity of the metal nano-structures [134,135]. To construct photonic switches, CQED systems consisting of single QDs and metallic nanowires have been proposed to utilize the "photon blockade" phenomenon in the strong coupling regime [41].…”

Active molecular plasmonics: tuning surface plasmon resonances by exploiting molecular dimensions

“…Due to the high sensitivity of SPs to the optical properties of dielectric materials surrounding the plasmonic nanostructures [38,39], use of tunable dielectric materials has proved to be an effective approach towards active plasmonics [40,41]. In particular, functional molecules and organic materials exhibit multiple advantages for the active plasmonic applications [42][43][44].…”