Product Code: ICA13_N302

Laser Fabricated Nanoantennas for Near-Field Applications
Authors:
Johannes Finger, Chair for Laser Technology, Rwth Aachen University; Aachen Germany
Martin Reininghaus, Chair for Laser Technology, Rwth Aachen University; Aachen Germany
Dirk Wortmann, Chair for Laser Technology, Rwth Aachen University; Aachen Germany
Zhao Cao, Chair for Laser Technology, Rwth Aachen University; Aachen Germany
Thomas Taubner, 1. Institute of Physics (Ia), Rwth Aachen University; Aachen Germany
Presented at ICALEO 2013

By irradiation of thin gold films with single pulses of fs-laser radiation, Gold nanoantennas with heights up to approximately 2 µm and tip diameters of less than 100 nm can be fabricated. The antennas exhibit resonant extinction in the near infrared and therefore can be used for optical near field amplification, with potential applications for e.g. surface enhanced raman spectroscopy.
Due to the free charge carriers within the gold film, image charges below the metallic film are introduced to describe the electrostatic field of the antenna. Thus the resonance wavelength is equal to four times the antenna length. This value is controlled coarsely by the focusing numerical aperture and fine by the pulse energy of the laser pulse to produce the structure. An additional fine tuning of the resonance wavelength with a sub-10nm resolution is realized by an additional coating process subsequent to the laser irradiation.