Resolution Analysis of a Polymethylmethacrylate Tapered Probe in Near-Field Terahertz Imaging
Keywords:
Near-field, Polymethylmethacrylate tapered probe, Terahertz imagingAbstract
A Polymethylmethacrylate (PMMA) rectangular tapered probe with metal coating on the sides is analyzed as a near-field imaging probe at 100 GHz in Ansoft High Frequency Structure Simulator (HFSS). Normally, highly resistive silicon and sapphire, which are costly, are used as a near-field probe due to their low loss and high permittivity. PMMA near-field probe is usually used in Scanning Near-field Optical Microscopy (SNOM), which is made from PMMA optical fibers. We propose for the first time to use PMMA as a near-field probe in millimeter and Terahertz wave scanning near-field imaging applications. The geometrical optimization of the tapered probe is carried out on the basis of different coupling methods. The beam shape merging from the end of the tapered tip is analyzed. The operation efficiency of two-side tapered and four-side tapered probes has been compared in view of the fabrication technique. A knife edge is simulated in HFSS to define the lateral resolution. Longitudinal resolution is discussed through setting a stair step shaped sample. A high lateral resolution around the end of the probe size can be achieved and even higher longitudinal resolution. The impact of the tip-sample distance and the lateral resolution are clearly illustrated via simulations. Experiments are carried out using a two-side tapered probe provided with an aluminum coating. The resolution is defined by scanning a PMMA board which was half coated with aluminum.
Downloads
References
A. Lewis, “Near-field optics: from subwavelength illumination to nanometric shadowing,” Nature Biotechnology, vol. 21, no. 11, pp. 1378-1386, 2003.
T. Nozokido, T. Ohbayashi, J. Bae, and K. Mizuno, “A resonant slit-type probe for millimeter-wave scanning near-field microscopy,” IEICE Trans. Electron., vol. E87-C, no. 12, 2004.
T. Nozokido, S. Nuimura, T. Hamano, J. Bae, and K. Mizuno, “A new object mounting structure for use in millimeter-wave scanning near-field microscopy,” IEICE Trans. Electron., vol. 1, no. 6, 144-149, 2004.
J. Bae, T. Okamoto, T. Fujii, and K. Mizuno, “Experimental demonstration for scanning nearfield optical microscopy using a metal micro-slit probe at millimeter wavelengths,” Applied Physics Letters, vol. 71, no. 24, pp. 3581-3583, 1997.
N. Klein, P. Lahl, and U. Poppe, “A metaldielectric antenna for terahertz near-field imaging,” Journal of Applied Physics, vol. 98, no. 014910, 2005.
O. Benzaim, K. Haddadi, M. M. Wang, D. Maazi, and T. Lasri, “Scanning near-field millimeter-wave microscope: application to a vector-coding technique,” IEEE Transaction on Instrumentation and Measurement, vol. 57, no. 11, pp. 2392-2397, 2008.
M. Kim, J. Kim, H. Kim, S. Kim, J. Yang, H. Yoo, S. Kim, K. Lee, and B. Friedman, “Nondestructive high spatial resolution imaging with a 60 GHz near-field scanning millimeter-wave microscope,” Review of Scientific Instruments, vol. 75, no. 3, pp. 684-688, 2004.
A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Letters, vol. 8 no. 11 pp. 3766-3770, 2008.
B. Zhu, S. Vanloocke, J. Stiens, D. De Zutter, and R. Vounckx, “A novel 3D printed focusing probe in scattering-type scanning near-field millimeter and terahertz wave microscope,” European Conference on Antennas and Propagation, Rome, Italy, pp. 775-778, 2011.
B. Zhu, J. Stiens, G. Poesen, S. Vanloocke, D. De Zutter, and R. Vounckx, “Dielectric analysis of 3D printed materials for focusing elements operating in Mm and THz wave frequency bands,” Proceedings of Symposium IEEE/LEOS Benelux Chapter, Delft, Netherland, pp. 13-16, 2010.
B. Zhu, S. Vanloocke, V. Matvejev, J. Stiens, D. De Zutter, and R. Vounckx, “Scanning near-field millimeter wave microscope combining dielectric tapered probes and metal tips,” Progress In Electromagnetics Research Symposium, Suzhou, China, pp. 12-16, September 2011.
B. Zhu, J. Stiens, V. Matvejev, and R. Vounckx, “Inexpensive and easy fabrication of multimode tapered dielectric circular probes at millimeter wave frequencis,” Progress In Electromagnetics Research, vol. 126, pp. 237-254, 2012.
H. Chibani, K. Dukenbayev, M. Mensi, S. K. Sekatskii, and G. Dietler, “Near-field scanning optical microscopy using polymethylmethacrylate optical fiber probes,” Ultramicroscopy, vol. 110, pp. 211-215, 2010.
B. Zhu, G. He, J. Stiens, and R. Vounckx, “Analysis and optimization of a focusing metaldielectric probe for near field terahertz imaging,” EuMW2013, Nuremberg, Germany, pp. 6~11, October 2013.
M. Berta, P. Kuzel, and F. Kadlec, “Study of responsiveness of near-field terhertz imaging probes,” J. Phys. D: Appl. Phys., vol. 42, 2009.
R. A. J. L. Adam, “Review of near-field terahertz measurement mehtods and their applications,” J. Infrared Milli. Terahz. Waves, vol. 32, pp. 976- 1019, 2011.
