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VERSION:2.0
PRODID:Icfo
X-PUBLISHED-TTL:P1W
BEGIN:VEVENT
UID:69db6d0e4250a
DTSTART:20221018T130000Z
SEQUENCE:0
TRANSP:OPAQUE
LOCATION:Online (Teams)
SUMMARY:ICFO | PABLO DE ROQUE
CLASS:PUBLIC
DESCRIPTION:Nanophotonics can be defined as the science and technology stud
 ying the control optical fields at the nanoscale and their interaction wit
 h matter. In order to spatially control such fields we would need structur
 es with characteristic dimensions of the order of the wavelength\, bringin
 g us to the nanoscale.\nA way to control optical fields at this scale is t
 he use of nanoantennas\, optical equivalent of radio-antennas. They provid
 e efficient interfaces between near-fields generated by light sources and 
 radiative channels. After a brief Introduction\, Chapter 2 describes inter
 action between single photon emitters and nanoantennas. We start the chapt
 er introducing a method to numerically simulate the interaction. A key con
 cept to solving Maxwell equations is that of the Green function. I show ho
 w this function relates to the emission rate of optical emitters in a nano
 photonic environment. I then describe an our efforts to build a lifetime-i
 maging near-field scanning optical microscope. Using this rig we are able 
 to measure changes changes in the emission rate of single emitters that in
 teract with resonant optical antennas.\nA complementary way to control opt
 ical field in the nanoscale is using dielectric confinement. Chapter 3 int
 roduces hybrid structures combining nanoantennas and dielectric waveguides
 . I generalize the Green function formalism introduced in Chapter 2\, and 
 show how this is related to the energy transfer rate between a donor and a
 n acceptor. I use this numerical method to calculate the energy transfer r
 ate in a hybrid structure. An increase of orders of magnitude is found at 
 distances of the order of the wavelengths of the transferred photons. This
  chapter finishes by discussing the role that the local density of optical
  states has on the energy transfer efficiency.\nNanoantennas increase near
 -field by orders of magnitude. In these conditions\, nonlinear optical eff
 ects start to play a role. Chapter 4 is devoted to these nonlinear interac
 tions mediated by nanoantennas. I explore nonlinear interactions in resona
 nt nanoantennas\, in particular SHG. First I introduce a method to numeric
 ally compute the contributions to SHG generated by the metal in nanoantenn
 as. Both surface and bulk contributions to SHG are considered. I use the n
 umerical method to show that narrowings within the antenna shape are sourc
 es of increased SHG. The increase in SHG is attributed to increase of the 
 local field gradients\, that increase to the bulk contribution to SHG. We 
 numerically validate our results by performing SHG measurements at the sin
 gle resonant antenna level.\nOptical fields are functions of space\, but a
 lso of time. The development of broadband femtosecond lasers and pulse sha
 ping techniques allows control of optical field down to the femtosecond ti
 mescale. Chapter 5 explores the control of optical fields in time. Using p
 hase shaping methods we optimize the two-photon absorption process in sing
 le QDs. I introduce a new optimization algorithm\, that allows us to perfo
 rm the optimization using as feedback signal the luminesce from single QDs
 . We then compare our results with standard phase shaping techniques.\nBas
 ed on their success to effectively control all kinds of optical fields\, p
 lasmon supporting nanoantennas are being actively researched in the field 
 of quantum optics. In Chapter 6 I describe a quantum eraser experiment med
 iated by structures supporting surface plasmon resonances. I first explain
  the details and subtleties of a quantum eraser experiment. I then detail 
 our efforts to reproduce previously reported results about how to fabricat
 e elliptical bullseye antennas behaving as quarter waveplates. Quarter wav
 eplates are a required part for the quantum eraser effect to take place. A
 n additional key component of our experiment is a bright\, state-of-the-ar
 t entangle polarization entangle photon source that is described at length
 . We then perform a quantum eraser experiment mediated by plasmons.\n&nbsp
 \;\nThesis Director: Prof Dr. Niek van Hulst
DTSTAMP:20260412T095942Z
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