A low cost and large-scale synthesis of 3D photonic crystal with SP2 lattice symmetry
Mei-Li Hsieh,
Shu-Yu Chen,
Alex Kaiser,
Yang-Jhe Yan,
B. Frey,
Ishwara Bhat,
Rajendra Dahal,
Sayak Bhattacharya,
Sajeev John,
Shawn-Yu Lin
Affiliations
Mei-Li Hsieh
Department of Photonics, National Chiao Tung University, Hsinchu 30050, Taiwan
Shu-Yu Chen
Department of Photonics, National Chiao Tung University, Hsinchu 30050, Taiwan
Alex Kaiser
The Future Chips Constellation and the Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA
Yang-Jhe Yan
Department of Photonics, National Chiao Tung University, Hsinchu 30050, Taiwan
B. Frey
The Future Chips Constellation and the Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA
Ishwara Bhat
Electrical Computer Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
Rajendra Dahal
Electrical Computer Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
Sayak Bhattacharya
Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada
Sajeev John
Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada
Shawn-Yu Lin
The Future Chips Constellation and the Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA
In this work, a novel lithographic method is proposed to prepare three-dimensional (3D) photonic crystal (PC) that is different from conventional top-down and bottom-up approaches. The method combines a 2D optical mask and off-the-axis double optical exposures to create a desirable 3D PC structure. Since the method uses only two optical exposures of a photo-resist layer, it is inherently a low-cost, high throughput and wafer-scale lithographic method. The method is implemented to make a slanted post 3D PC having the SP2 lattice symmetry. Three types of SP2 3D PC structures were successfully fabricated with a minimum feature size of d=1.5 μm over a large scale of 8x10 mm2, without any observable fabrication defects. The SP2 PCs are: (i) SU8 posts in air background, (ii) air pores in CdS background and (iii) Pt coated on SU8 SP2 templates. A spectroscopic study of the SP2 PCs shows select spectral regions of high reflectance, indicating the existence of a photonic stop band. This low-cost and large-scale method could enable broader technological impacts of 3D PC materials in areas such as thermo-photovoltaics and above room-temperature Bose-Einstein Condensation. Furthermore, this off-axis method could lead to the creation of an entirely new class of slanted-rod based photonic crystals, such as topological photonic crystal in 3D.
