Microfabrication of SU-8 Fresnel lenses for THz imaging

M. Hajji; Y. Pan; J. Hammler; D. Zeze; C. Balocco; A. J. Gallant

doi:10.1117/12.2208664

25 February 2016 Microfabrication of SU-8 Fresnel lenses for THz imaging

M. Hajji, Y. Pan, J. Hammler, D. Zeze, C. Balocco, A. J. Gallant

Proceedings Volume 9747, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX; 97470N (2016) https://doi.org/10.1117/12.2208664
Event: SPIE OPTO, 2016, San Francisco, California, United States

Abstract

Free space focusing of terahertz light is normally achieved through the use of bulky parabolic mirrors. Alternatively, for focusing onto a substrate or sample, polished high resistivity silicon lenses are commonly used. This paper presents the design, fabrication and testing of an alternative approach, based on Fresnel microlenses which have been optimised for use in the terahertz region. The microlenses are fabricated using layers of SU-8 photoresist and conventional UV photolithography. The lens design approach presented here provides a low cost, mass production ready alternative to silicon lenses. Fresnel lenses can have a large numerical aperture and a short focal length and are well suited for use in terahertz imaging systems. The focal point of the demonstrated Fresnel microlens has been calculated to be approximately 5 mm at 1 THz using a commercial FDTD solver, Lumerical. Characterization of the microlenses by VNA (Vector Network Analyzer) operating in the frequency range of 750 GHz to 1.1 THz is presented and discussed. The measured focal length using the VNA approach corresponds well to the values calculated using the FDTD solver and demonstrates effective focusing from highly compact lenses.

Citation Download Citation

M. Hajji, Y. Pan, J. Hammler, D. Zeze, C. Balocco, and A. J. Gallant "Microfabrication of SU-8 Fresnel lenses for THz imaging", Proc. SPIE 9747, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX, 97470N (25 February 2016); https://doi.org/10.1117/12.2208664

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available