Nano Archive

A nonvolatile plasmonic switch employing photochromic molecules

Pala, Ragip A. and Shimizu, Ken T. and Melosh, Nicholas A. and Brongersma, Mark L. (2008) A nonvolatile plasmonic switch employing photochromic molecules. NANO LETTERS, 8 (5). pp. 1506-1510.

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We demonstrate a surface plasmon-polariton (SPP) waveguide all-optical switch that combines the unique physical properties of small molecules and metallic (plasmonic) nanostructures. The switch consists of a pair of gratings defined in an aluminum film coated with a 65 nm thick layer of photochromic (PC) molecules. The first grating couples a signal beam consisting of free space photons to SPPs that interact effectively with the PC molecules. These molecules can reversibly be switched between transparent and absorbing states using a free space optical pump. In the transparent (signal ``on'') state, the SPPs freely propagate through the molecular layer, and in the absorbing (signal ``off'') state, the SPPs are strongly attenuated. The second grating serves to decouple the SPPs back into a free space optical beam, enabling measurement of the modulated signal with a far-field detector. In a preliminary study, the switching behavior of the PC molecules themselves was confirmed and quantified by surface plasmon resonance spectroscopy. The excellent (16%) overlap of the SPP mode profile with the thin layer of switching molecules enabled efficient switching with power densities of similar to 6.0 mW/cm(2) in 1.5 mu m x 8 mu m devices, resulting in plasmonic switching powers of 0.72 nW per device. Calculations further showed that modulation depths in access of 20 dB can easily be attained in optimized designs. The quantitative experimental and theoretical analysis of the nonvolatile switching behavior in this letter guides the design of future nanoscale optically or electrically pumped optical switches.

Item Type:Article
Subjects:Physical Science > Photonics
Engineering > Nanotechnology applications in ICT
ID Code:1879
Deposited By:Farnush Anwar
Deposited On:16 Dec 2008 15:25
Last Modified:12 Jan 2009 11:28

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