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SUMMARY:Beyond plasmonics: oxide and semiconductor nanomaterials  for enha
 ncing nonlinear optical signals
DTSTART:20170424T131500
DTEND:20170424T141500
DTSTAMP:20260509T131633Z
UID:e3efe5599e9146fd8acf50db0fe16918f38c06b2143e93f88ba87cf1
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Rachel Grange\, EPFZ\nNonlinear optical processes are kn
 own to be weak in bulk materials and extremely small at the nanoscale sinc
 e they mainly scale with the volume. Here I will show several strategies t
 o maximize nonlinear optical signals in nano-oxides with Perovskite crysta
 lline structure and in III-V nanowires. First\, I will demonstrate how we 
 enhance second-harmonic generation (SHG) by using the scattering propertie
 s of individual barium titanate (BaTiO3) nanoparticles. We use the Mie res
 onances to achieve an SHG enhancement of four orders of magnitude within t
 he same nanoparticle1. Our results suggest that a strong increase of the S
 HG signal can be obtained without using plasmonic or hybrid nanostructures
 .\n \nBesides chemically synthesized nanostructures\, we developed lithog
 raphy processes to obtain high aspect ratio lithium niobate (LiNbO3) nanow
 aveguides. We demonstrate phase-matching and use it to increase the guided
  SHG power by a factor of more than 40. We also increase non-phase-matched
  guided second-harmonic by engineering the nanowire length2\,3. Those brig
 ht nanostructures can serve for developing compact efficient nonlinear opt
 ical sources or waveguides. Finally I will report on cavity effects in GaA
 s nanowires and on a powerful multiphoton imaging method to distinguish va
 rious crystal structures in individual nanowires4.\n \n \n \nReferences
 \n \n(1)           Timpu\, F.\; Sergeyev\, A.\; Hendricks\, N. R
 .\; Grange\, R. Second-Harmonic Enhancement with Mie Resonances in Perovsk
 ite Nanoparticles. ACS Photonics 2017\, 4\, 76–84.\n(2)         
   Sergeyev\, A.\; Geiss\, R.\; Solntsev\, A. S.\; Sukhorukov\, A. A.\; Sc
 hrempel\, F.\; Pertsch\, T.\; Grange\, R. Enhancing Guided Second-Harmonic
  Light in Lithium Niobate Nanowires. ACS Photonics 2015\, 2\, 687–691.\n
 (3)           Sergeyev\, A.\; Reig Escalé\, M.\; Grange\, R. Gen
 eration and Tunable Enhancement of Sum-Frequency Signal in Lithium Niobate
  Nanowires. J. Phys. D Appl. Phys 2017\, 50.\n(4)           Timof
 eeva\, M.\; Bouravleuv\, A.\; Cirlin\, G.\; Shtrom\, I.\; Soshnikov\, I.\;
  Reig Escalé\, M.\; Sergeyev\, A.\; Grange\, R. Polar Second-Harmonic Ima
 ging to Resolve Pure and Mixed Crystal Phases along GaAs Nanowires. Nano L
 ett. 2016\, 16\, 6290–6297.\n\nBio:\nRachel Grange graduated in Physics 
 at EPFL in 2002 and obtained her PhD in ultrafast laser physics at ETH Zur
 ich in 2006. During her post-doc with D. Psaltis\, she worked on nonlinear
  bioimaging with Perovskite nanoparticles. From 2011 to 2014\, she was gro
 up leader at the Friedrich Schiller University in Jena Germany. Since Janu
 ary 2015\, she is assistant professor at the Department of Physics at ETH 
 Zurich. Her laboratory investigates the optical behavior of nanomaterials 
 for developing applications in optoelectronics or imaging. In 2016\, she r
 eceived an ERC starting grant to work on strategies to enhance optical non
 linearities in oxide nanomaterials.\n\n \n \n 
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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