BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:America/New_York BEGIN:DAYLIGHT DTSTART:20250309T030000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3 TZNAME:EDT END:DAYLIGHT BEGIN:STANDARD DTSTART:20251102T010000 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11 TZNAME:EST END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20250919T173239Z UID:300DECDD-8894-4E17-B093-041257EBD83E DTSTART;TZID=America/New_York:20250918T110000 DTEND;TZID=America/New_York:20250918T120000 DESCRIPTION:Abstract: In this talk\, we will discuss two recent observation s from our group that have challenged widespread assumptions held (by us i ncluded!) about the optical response of commonly used optical materials: t hat material polarization can safely be considered to respond locally to t he electric field and that the second-order nonlinear response of amorphou s films should vanish due to centrosymmetry. In the first part of the talk \, we will describe our proposal for a new type of optical antenna dubbed a “photonic gap antenna”\, and our realization of its extreme version using an epsilon-near-zero (ENZ) material. Such antennas can provide elect ric field enhancements of >100 and large Purcell factors without requiring stringent nanofabrication. To our surprise\, when measuring third harmoni c generation as a proxy for field enhancement\, sharp peaks emerge in the response that are completely absent in our full wave electromagnetic calcu lations. We find that the appearance of these peaks can only be explained when including nonlocality in the dielectric response of the ENZ material. Nonlocal simulations show that the volume averaged field enhancement can be 4–6 greater than that predicted by the local model\, which becomes an important consideration when designing optical devices. In the second par t of the talk\, we will describe our recent discovery that amorphous therm ally evaporated organic thin films of small molecules can have second-orde r optical nonlinearities on par with those of state-of-the-art nonlinear m aterials (c(2)31\, c(2)33 >50 pm/V)\, with the important advantage that th ey can be deposited on arbitrary photonic platforms. We will show that by harnessing the interplay between dipole-dipole interactions and surface en ergy minimization\, it is possible to spontaneously break centrosymmetry d uring thermal evaporation\, without the need for special alignment procedu res. In addition to its applications in photonics\, this observation has a llowed us to better understand molecular alignment beyond the mean molecul ar orientation angle.\n\n.\n\nCo-sponsored by: Prof. Nicolas Quesada\n\nSp eaker(s): Stéphane Kéna-Cohen\n\nJ. Armand Bombardier J-1035\, Polytechn ique Montréal\, Montréal\, Quebec\, Canada\, H3T 1J4 LOCATION:J. Armand Bombardier J-1035\, Polytechnique Montréal\, Montréal\ , Quebec\, Canada\, H3T 1J4 ORGANIZER:nicolas.quesada@polymtl.ca SEQUENCE:118 SUMMARY:Recent surprises in nonlocal and nonlinear photonics URL;VALUE=URI:https://events.vtools.ieee.org/m/499775 X-ALT-DESC:Description: <br /><div><img src="https://events.vtools.ieee.org /vtools_ui/media/display/2d62542a-7acc-458f-84f6-5fe2d1ef15e0" width="917" height="509"></div>\n<div>&nbsp\;</div>\n<div><span style="font-family: ' times new roman'\, times\, serif\;"><strong>Abstract: </strong><span style ="font-size: 12pt\;"><span lang="EN-CA" style="font-family: 'Times New Rom an'\, serif\;">In this talk\, we will discuss two recent observations from our group that have challenged widespread assumptions held (by us include d!) about the optical response of commonly used optical materials: that ma terial polarization can safely be considered to respond locally to the ele ctric field and that the second-order nonlinear response of amorphous film s should vanish due to centrosymmetry. In the first part of the talk\, we will describe our proposal for a new type of optical antenna dubbed a &ldq uo\;photonic gap antenna&rdquo\;\, and our realization of its extreme vers ion using an epsilon-near-zero (ENZ) material. Such antennas can provide e lectric field enhancements of &gt\;100 and large Purcell factors without r equiring stringent nanofabrication. To our surprise\, when measuring third harmonic generation as a proxy for field enhancement\, sharp peaks emerge in the response that are completely absent in our full wave electromagnet ic calculations. We find that the appearance of these peaks can only be ex plained when including nonlocality in the dielectric response of the ENZ m aterial. Nonlocal simulations show that the volume averaged field enhancem ent can be 4&ndash\;6 greater than that predicted by the local model\, whi ch becomes an important consideration when designing optical devices. In t he second part of the talk\, we will describe our recent discovery that am orphous thermally evaporated organic thin films of small molecules can hav e second-order optical nonlinearities on par with those of state-of-the-ar t nonlinear materials (</span><span lang="EN-CA" style="font-family: Symbo l\;">c<sup>(2)</sup></span><sub><span lang="EN-CA" style="font-family: 'Ti mes New Roman'\, serif\;">31</span></sub><span lang="EN-CA" style="font-fa mily: 'Times New Roman'\, serif\;">\, </span><span lang="EN-CA" style="fon t-family: Symbol\;">c<sup>(2)</sup></span><sub><span lang="EN-CA" style="f ont-family: 'Times New Roman'\, serif\;">33</span></sub><span lang="EN-CA" style="font-family: 'Times New Roman'\, serif\;"> &gt\;50 pm/V)\, with th e important advantage that they can be deposited on arbitrary photonic pla tforms. We will show that by harnessing the interplay between dipole-dipol e interactions and surface energy minimization\, it is possible to spontan eously break centrosymmetry during thermal evaporation\, without the need for special alignment procedures. In addition to its applications in photo nics\, this observation has allowed us to better understand molecular alig nment beyond the mean molecular orientation angle</span>.</span></span>\n< p aria-hidden="true"><span style="font-family: 'times new roman'\, times\, serif\;">&nbsp\;</span></p>\n.</div> END:VEVENT END:VCALENDAR