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SUMMARY:Nanoscale 3D Printing of Structural Colors and Multi-Spectral Filt
 ers for Light Control
DTSTART:20250630T120000
DTEND:20250630T130000
DTSTAMP:20260501T182940Z
UID:80ab03638b95215db0121489d5dfae44879185a7832c83b89ada3b0f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Joel K.W. Yang\, Department of Engineering Product Deve
 lopment\, Singapore University of Technology and Design\, Singapore (SG)\
 nPHOTONICS\, MICRO- and BIOENGINEERING SEMINAR\n \nAbstract:\n3D printing
  is a cost-effective and effective means to rapidly prototype and test out
  designs. In our cleanroom\, we use high-resolution 3D printers based on t
 wo-photon polymerization lithography (TPL) with light (780 nm wavelength f
 emtosecond lasers) to quickly realize nanoscale structures that are design
 ed to control light. Producing structures with TPL for optical application
 s is a relatively new endeavor in additive manufacturing [1]\, with capabi
 lities to create freeform structures at dimensions matching the wavelength
  of light. We have demonstrated the printing of structural colors\, genera
 ted from nanoscale features of dielectric materials. Examples include TPL 
 printing of nanopillars\, gratings\, mesh-like\, and wood-pile photonic cr
 ystal structures that appear colorful under white-light illumination. The 
 ability to achieve a wide range of colors by simply tuning geometric prope
 rties opens fascinating opportunities to the nanoengineer or nanoscientist
  to design colors using material properties\, and nanostructure geometry a
 s input parameters. This physical approach differs from the chemical appro
 ach for synthesizing pigments and dyes\, where colors arise due to optical
  absorption. We recently extended a “print and shrink” process to prod
 uce photonic crystals with bandgaps in the visible spectrum\, e.g. see Fig
 . 1. We formulated resins that result in structures of both high and low i
 ndex dielectrics\, respectively titanium dioxide [2]\, and glass [3]. The 
 3D printed structures remarkably show excellent lattice uniformity with me
 asured angle-dependent reflectance spectra that agree well with bandstruct
 ure calculations. Equipped with TPL as a nanoscale 3D printer\, structural
  color geometries are conveniently integrated in a single print run with o
 ther user-defined optics. Doing so enables one to produce structured light
  from incoherent light sources\, holographic color prints\, and control of
  the light-field for 3D representation. We will discuss the use of structu
 ral colors combined with micro-optics for enhanced information content and
  optical security [4].\n\nReferences\n1. Hao Wang\, et al. “Two-Photon P
 olymerization Lithography for Optics and Photonics: Fundamentals\, Materia
 ls\, Technologies\, and Applications”\, Adv. Funct. Mater. 2214211 (2023
 )\n2. Wang Zhang\, et al.\, “Printing of 3D photonic crystals in titania
  with complete bandgap across the visible spectrum”\, Nature Nanotechnol
 ogy volume 19\, pages1813–1820 (2024)\n3. Wang Zhang\, et al.\,“Nanosc
 ale 3D printing of glass photonic crystals with near-unity reflectance in 
 the visible spectrum”\, Science Advances Vol 11\, Issue 21(2025)\n4. Hon
 gtao Wang\, et al. “Coloured vortex beams with incoherent white light il
 lumination”\, Nature Nanotechnology 18\, 264–272 (2023)\n\nBio:\nJoel 
 Yang received his Master of Science (2005) and PhD (2009) degrees from the
  Massachusetts Institute of Technology\, Department of Electrical Engineer
 ing and Computer Science. He is a Professor\, Cleanroom Director and Assoc
 iate Head of Department in Engineering Product Development at the Singapor
 e University of Technology and Design (SUTD). He is recognized for pioneer
 ing work in plasmonic color printing\, achieving record-level printing res
 olution at 100\,000 dpi and credited for the widely-used “salty-develope
 r” to improve the resolution of electron beam lithography. His research 
 interests include Structural color printing\, Nanoplasmonics\, 2D and 3D p
 rinted nano optical design elements (NODE)\, and sub-10-nm resolution lith
 ography. He is Fellow of Optica\, NRF Investigator (class of 2020)\, and A
 *STAR Investigator (2010).\n\n\nZoom link for attending remotely:  https:/
 /epfl.zoom.us/j/63256411470\n\n\nInstructions for 1st-year Ph.D. students 
 planning to attend this talk\, who are under EDBB’s mandatory seminar at
 tendance rule:\nIN CASE you cannot attend in-person in the room\, please m
 ake sure to\n\n	send D. Reinhard a note well ahead of time (ideally before
  seminar day)\, informing that you plan to attend the talk online\, and\, 
 during seminar:\n	be signed in on Zoom with a recognizable user name (not 
 any alias making it difficult or impossible to identify you).\n\nStudents 
 attending the seminar in-person should collect a confirmation signature af
 ter the talk - please print your own signature sheet beforehand (69 kB pdf
  available for download here). IMPORTANTLY: hang on to this sheet as no si
 gnature record is being kept by anyone else!
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717 https://epfl.zoom.u
 s/j/63256411470
STATUS:CONFIRMED
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