Enhanced Propagating Surface Plasmon Signal Detection
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- 作者：Y. Gong ; Alan G. Joly ; Patrick Z. El-Khoury ; Wayne P. Hess
- 刊名：ACS Photonics
- 出版年：2016
- 出版时间：December 21, 2016
- 年：2016
- 卷：3
- 期：12
- 页码：2413-2419
- 全文大小：570K
- ISSN：2330-4022
文摘
Overcoming the dissipative nature of propagating surface plasmons (PSPs) is a prerequisite to realizing functional plasmonic circuitry, in which large-bandwidth signals can be manipulated over length scales far below the diffraction limit of light. To this end, we report on a novel PSP-enhanced signal detection technique achieved in an all-metallic substrate. We take advantage of two strategically spatiotemporally separated phase-locked femtosecond laser pulses, incident onto lithographically patterned PSP coupling structures. We follow PSP propagation with joint femtosecond temporal and nanometer spatial resolution in a time-resolved nonlinear photoemission electron microscopy scheme. Initially, a PSP signal wave packet is launched from a hole etched into the silver surface from where it propagates through an open trench structure and is decoded through the use of a timed probe pulse. FDTD calculations demonstrate that PSP signal waves may traverse open trenches in excess of 10 μm in diameter, thereby allowing remote detection even through vacuum regions. This arrangement results in a 10× enhancement in photoemission relative to readout from the bare metal surface. The enhancement is attributed to an all-optical homodyne detection technique that mixes signal and reference PSP waves in a nonlinear scheme. Larger readout trenches achieve higher readout levels; however reduced transmission through the trench limits the trench size to 6 μm for maximum readout levels. In addition, the use of an array of trenches increases the maximum enhancement to near 30×. The attainable enhancement factor may be harnessed to achieve extended coherent PSP propagation in ultrafast plasmonic circuitry.