A nonvolatile plasmonic switch employing photochromic molecules.
Ragip A Pala1, Ken T Shimizu, Nicholas A Melosh
1Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
Nano Letters
|April 17, 2008
Summary
We developed an all-optical switch using surface plasmon-polaritons (SPPs) and photochromic molecules. This device efficiently modulates light signals with low power, paving the way for nanoscale optical switches.
Area of Science:
- Photonics and Nanotechnology
- Materials Science
Background:
- Surface plasmon-polaritons (SPPs) offer unique light-matter interaction properties.
- Photochromic (PC) molecules provide reversible optical switching capabilities.
Purpose of the Study:
- To demonstrate an all-optical switch utilizing SPPs and PC molecules.
- To investigate efficient light modulation at the nanoscale.
Main Methods:
- Fabrication of an aluminum film waveguide with gratings and a PC molecule layer.
- Coupling free space photons to SPPs interacting with PC molecules.
- Modulating SPP propagation using an optical pump to switch PC molecules between transparent and absorbing states.
- Utilizing a second grating to decouple SPPs back into a detectable optical beam.
Main Results:
- Confirmed and quantified PC molecule switching behavior using surface plasmon resonance spectroscopy.
- Achieved efficient switching with low power densities (approx. 6.0 mW/cm²) due to strong SPP mode overlap (16%) with the PC layer.
- Demonstrated plasmonic switching powers of 0.72 nW per device.
- Calculations indicate potential for >20 dB modulation depths in optimized designs.
Conclusions:
- The developed SPP waveguide all-optical switch effectively utilizes the properties of PC molecules and plasmonic nanostructures.
- Efficient, low-power optical switching is achievable, guiding future designs for nanoscale optical or electrical switches.
