Proceedings Article | 19 April 2017
KEYWORDS: Absorption, Plasmonics, Light, Photocatalysis, Sensors, Modulation, Electromagnetism, System on a chip, Photonics, Ultrafast phenomena
The electro-magnetic field generated within and around dissipative nano-structures upon light radiation is intimately associated to the formation of localized heat sources. In turn, this phenomenon determines localized temperature variations, effect which can be exploited for applications such as photocatalysis [1], nanochemistry [2] or sensor devices [3].
Here we show how the geometrical characteristics of plasmonic nano-structures can indeed be used to modulate the temperature response. The idea is that when metallic structures interact with an electromagnetic field they heat up due to Joule effect. The corresponding temperature variation modifies the optical response of the structure [4,5] and thus its heating process. The key finding is that, depending on the structures geometry, absorption efficiency can either increase or decrease with temperature. Since absorption relates to the thermal energy dissipation and thus to temperature increase, the mechanism leads to positive or negative loops. Consequently, not only an error would be made by neglecting the role of temperature, but it would be not even possible to know, a priori, if the error is towards higher or lower absorption values.
Our model can be utilized to study opto-thermal phenomena when high temperature or high intensity sources are employed.
[1] M. Honda et al., Appl. Phys. Lett. 104, 061108 (2014)
[2] G. Baffou et al., Chem. Soc. Rev. 43, 3898 (2014)
[3] S. Ozdemir et al., J. Lightwave Tech. 21, 805 (2003)
[4] A. Alabastri et al., ACS Photonics 2, 115 (2015)
[5] A. Alabastri et al., Materials 6, 4879 (2013)
