Multi-photon Polymerization of Embedded Features in Photonic Crystals and Directed Self-Assembly of Colloidal Crystals
Wonmok Lee, Former Postdoctoral Fellow currently at Samsung
(Ph.D. in Polymer Chemistry, Pohang Univ.of Sci. and Tech, ’01)
I’m working on a research project where we intend to develop 3-dimensional (3D) photonic bandgap (PBG) components which will eventually enable on-chip integration of photonic devices. Instead of using microlithographic techniques which are expensive and tedious, we focus on colloidal self-assembly as a route to prepare templates for PBG materials. Within the 3D space of the FCC colloidal crystal, I fabricate a variety of defect structures, such as waveguides, by multi-photon polymerization. (see Figure 1) In doing so, I utilize a laser scanning confocal microscopy combined with various laser sources to realize both fabrication and imaging of submicron waveguide structures.
Fig. 1 Confocal microscope image of PBG waveguide structure fabricated by two-photon polymerization in a 3D colloidal crystal. (a) Side-view, (b) Cross section of waveguide (bright region in the center of the picture). The diameter of each sphere is about 1.6 microns.
Such a colloidal crystal with an embedded waveguide structure can then be infiltrated with high dielectric material to increase the dielectric contrast. (Link to Steph’s page) Another essential requirement for PBG material is a defect-free single crystalline structure on the millimeter length scale. I’m currently designing and fabricating various templates on either silicon- or silica-based substrates which are expected to induce the assembly of a single crystal colloidal crystal. The template fabrication methods include techniques such as optical lithography, micro-contact printing, focused ion beam lithography, etc.
Professor Paul Braun • Phone: +1.217.244.7293 • Fax: +1.217.333.2736 • Email: pbraun@uiuc.edu
Department of Materials Science and Engineering • University of Illinois at Urbana-Champaign