volume | PIER Journals

Abstract

Tapered dielectric fibers are widely used in the near field microscopy to focus the incident beam or collect near field signal. Single mode is always required so that the geometrical dimension of the waveguide is smaller than the wavelength. This paper proposes an inexpensive and easy fabrication of multimode tapered Teflon probe which has bigger dimensions than the wavelength. The field distribution in and outside the probe is analyzed by the total internal reflection theorem and solid core circular dielectric waveguide theory. Simulations are carried out in Microwave Studio CST. Novel applications based on focal points in and outside the probe are discussed, especially dielectric permittivity sensing of biomolecules using a capillary tube is emphasized by the simulations and experiments.

1. Causa, F., J. Sarma, and M. Milani, "Computation of propagation in adiabatically tapered dielectric structures based on eigenfunction expansions: Application to (active) optical devices," Antennas and Propagation Society International Symposium, Vol. 2, 762-765, 1997.

2. Snyder, A. W., "Coupling of modes on a tapered dielectric cylinder," IEEE Transactions on Microwave Theory and Techniques, Vol. 18, No. 7, 383-392, 1970.
doi:10.1109/TMTT.1970.1127247

3. Kobayashi, S. and R. Mittra, "Dielectric tapered rod antennas for millimeter-wave applications," IEEE Transactions on Antennas and Propagation, Vol. 30, No. 1, 54-58, 1982.
doi:10.1109/TAP.1982.1142758

4. De, A. and G. V. Attimarad, "Numerical analysis of two dimensional tapered dielectric waveguide," Progress In Electromagnetics Research, Vol. 44, 131-142, 2004.
doi:10.2528/PIER03062001

5. Choudhury, P. K. and W. K. Soon, "TE mode propagation through tapered core liquid crystal optical fibers," Progress In Electromagnetics Research, Vol. 104, 449-463, 2010.
doi:10.2528/PIER10021104

6. Zheng, X., "Understanding radiation from dielectric tapers," JOSA A, Vol. 6, No. 2, 190-201, 1989.
doi:10.1364/JOSAA.6.000190

7. Papakonstantinou, I., D. R. Selviah, and F. A. Fernandez, "Multimode polymer bent tapered waveguide modeling," Lasers and Electro-Optics Society, LEOS, Vol. 2, 983-984, 2004.

8. Choudhury, P. K. and P. T. S. Ping, "On the dispersion relations of tapered core optical fibers with liquid crystal clad," Progress In Electromagnetics Research, Vol. 118, 117-133, 2011.
doi:10.2528/PIER11052403

9. Soenmez, Y., A. Wallrabenstein, J. Schrage, and G. Mrozynski, "Coupled mode analysis of power transport and loss in highly multimodal tapered dielectric waveguides for coupling applications," Lasers and Electro-Optics | Pacific Rim, CLEO/Pacific Rim, Vol. 2, 1-2, 2007.

10. Adam, A. J. L., "Review of near-field terahertz measurement methods and their applications," International Journal of Infrared and Millimeter Waves, Vol. 32, 976-1019, 2011.

11. Yeh, C. and I. F. Shimabukuro, The Essence of Dielectric Waveguides, Springer, New York, 2008.

12. Zhu, B., 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, 13-16, Delft, Netherland, 2010.

13. Zhu, B., 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, EuCAP, 775-778, Rome, Italy, 2011.

14. Zhu, B., 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," PIERS Proceedings, Vol. 7, No. 6, Suzhou, China, Sept. 12-16, 2011.

15. Peeters, J., J. Fostier, F. Olyslager, and D. De Zutter, "New parallel approaches for fast multipole solvers," European Conference on Antennas and Propagation, EuCAP, 5-8, 2007.
doi:10.2976/1.2976661

16. Leitner, D. M., M. Gruebele, and M. Havenith, "Solvation dynamics of biomolecules: Modeling and terahertz experiments," HFSP J., Vol. 2, 314-323, Dec. 2008.

17. Tielrooij, K. J., D. L. Paparo, H. Piatkowski, J. Bakker, and M. Bonn, "Dielectric relaxation dynamics of water in model membranes probed by terahertz spectroscopy," Biophys. J., Vol. 97, 2484-2492, Nov. 2009.
doi:10.1063/1.1332415

18. Brucherseifer, M., M. Nagel, P. Bolivar, H. Kurz, A. Bosserhoff, and R. Buttner, "Label-free probing of the binding state of dna by time-domain terahertz sensing," Appl. Phys. Lett., Vol. 77, 4049-4051, Dec. 2000.

19. Markelz, A., S. Whitmire, J. Hillebrecht, and R. Birge, "THz time domain spectroscopy of biomolecular conformational modes," Phys. Med. Biol., Vol. 47, 3797-3805, Nov. 2002.

20. Markelz, A. G., "Terahertz dielectric sensitivity to biomolecular structure and function," IEEE J. Sel. Top. Quant., Vol. 14, 180-190, Jan.-Feb. 2008.
doi:10.2528/PIER11090102

21. Matvejev, V., C. De Tandt, W. Ranson, J. Stiens, R. Vounckx, and D. Mangelings, "Integrated waveguide structure for highly sensitive THz spectroscopy of nano-liter liquids in capillary tubes," Progress In Electromagnetics Research, Vol. 121, 89-101, 2011.

22. Matvejev, V., C. De Tandt, W. Ranson, and J. Stiens, "Wet silicon bulk micromachined THz waveguides for low-loss integrated sensor applications," IEEE 35th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2010), 2, Piscataway, NJ, USA, 2010.
doi:10.1016/0009-2614(90)87204-5

23. Barthel, J., K. Bachhuber, R. Buchner, and H. Hetzenauer, "Dielectric spectra of some common solvents in the microwave region --- Water and lower alcohols," Chem. Phys. Lett., Vol. 165, 369-373, Jan. 1990.

Miss Bin Zhu

Dr. Johan Stiens

Dr. Vladimir Matvejev

Dr. Roger Vounckx