title: Aligned copper nanorod arrays for highly efficient generation of intense ultra-broadband THz pulses.
abstract: We demonstrate an intense broadband terahertz (THz) source based on the interaction of relativistic-intensity femtosecond lasers with aligned copper nanorod array targets. For copper nanorod targets with a length of 5 μm, a maximum 13.8 times enhancement in the THz pulse energy (in ≤20 THz spectral range) is measured as compared to that with a thick plane copper target under the same laser conditions. A further increase in the nanorod length leads to a decrease in the THz pulse energy at medium frequencies (≤20 THz) and increase of the electromagnetic pulse energy in the high-frequency range (from 20-200 THz). For the latter, we measure a maximum energy enhancement of 28 times for the nanorod targets with a length of 60 μm. Particle-in-cell simulations reveal that THz pulses are mostly generated by coherent transition radiation of laser produced hot electrons, which are efficiently enhanced with the use of nanorod targets. Good agreement is found between the simulation and experimental results.
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Mondal
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: Q
authors.initials: Q
authors.lastname: Wei
authors.affiliation: A*STAR Institute of High Performance Computing, Singapore 138632.
authors.forename: W J
authors.initials: WJ
authors.lastname: Ding
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.|Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.|Physics Department, Faculty of Science, Helwan University, 11792, Cairo, Egypt.
authors.forename: H A
authors.initials: HA
authors.lastname: Hafez
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Fareed
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Laramée
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: X
authors.initials: X
authors.lastname: Ropagnol
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Sun
authors.affiliation: SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK.|Laboratory for Laser Plasmas and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.|Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Z M
authors.initials: ZM
authors.lastname: Sheng
authors.affiliation: Laboratory for Laser Plasmas and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.|Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Institut national de la recherche scientifique - Centre Energie, Matériaux et Télécommunications (INRS-EMT), 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Ozaki