Direct Fabrication of sub 100 nm Nanoneedles in Silver using Femtosecond Laser Direct Writing

Venugopal Rao Soma; Balaji Yendeti

doi:10.14429/dsj.70.14823

Venugopal Rao Soma Advanced Centre for Research in High Energy Materials, University of Hyderabad, Hyderabad - 500 046
Balaji Yendeti Advanced Centre for Research in High Energy Materials, University of Hyderabad, Hyderabad - 500 046

DOI: https://doi.org/10.14429/dsj.70.14823

Keywords: Laser processing, Raman, Femtosecond, Silver nanoneedles

Abstract

Novel methods for production of nanomaterials are urgently needed for various applications, especially in defence. In this work, we propose a direct method to produce silver nanoneedles using the femtosecond laser direct writing (LDW) technique. Femtosecond pulses were focused by a microscope objective on to a metal sheet to produce the nanoneedles. Nanoneedles of required dimensions were fabricated with a simple replacement of microscope objective of different numerical aperture. Further, we have investigated the effect of confinement. Finally, the application of nanoneedles is demonstrated for trace level detection of picric acid using surface enhanced Raman spectroscopy and a field deployable portable Raman spectrometer.

Author Biographies

Venugopal Rao Soma, Advanced Centre for Research in High Energy Materials, University of Hyderabad, Hyderabad - 500 046

Prof. S. Venugopal Rao obtained his Master’s and PhD from University of Hyderabad, India in 1994 and 2000, respectively. He has established Advanced Centre for High Energy Materials at University of Hyderabad. His research interests include detection of explosives using the techniques of SERS, LIBS, CARS and ultrafast laser-matter interaction. He has published 1 book, 10 book chapters, and >300 papers in journals/conference proceedings. He is Fellow of Institute of Physics, London, UK and the Telangana Academy of Sciences, Hyderabad. He is also a Senior Member of the OSA, IEEE, SPIE.

Balaji Yendeti, Advanced Centre for Research in High Energy Materials, University of Hyderabad, Hyderabad - 500 046

Dr Balaji Yendeti received his PhD in Physics from School of Physics, University of Hyderabad, in 2015. He did post-doctoral research at Tata Centre for Interdisciplinary Sciences, in 2016 and Advanced Centre for High Energy Materials, during 2017-19. He is currently working as project co-ordinator/Senior optical engineer in Ananth Technologies Limited (ATL), Hyderabad. His current research interests are thermal imaging and Lidar applications.