volume | PIER Journals

Abstract

Planar waveguides with an isotropic chiral core, called chirowaveguides, support the propagation of elliptically polarized modes, making them natural candidates for chiral sensing. We investigate the potential of chirowaveguides as optical sensors responding to changes in the circular birefringence of a medium covering the waveguide. Using first order approximations, we derive expressions for the sensitivities to refractive index and to changes in circular birefringence. The chiral sensitivity is proportional to the achiral sensitivity and to the eccentricity of the mode under consideration. Possible combinations of materials and design conditions for chirowaveguide sensors are discussed with reference to these results. The motivation for this study, besides its theoretical and academic importance, comes from potential applications for enantiomeric integrated optical devices.

1. Barron, L. D., Molecular Light Scattering and Oprical Activity, Cambridge University Press, Cambridge, 2004.
doi:10.1017/CBO9780511535468

2. Torsi, L., G. M. Farinola, F. Marinelli, M. C. Tanese, O. H. Omar, L. Valli, F. Babudri, F. Palmisano, P. G. Zambonin, and F. Naso, "A sensitivity-enhanced field-effect chiral sensor," Nat. Mater., Vol. 7, No. 5, 412-417, 2008.
doi:10.1038/nmat2167

3. Engheta, N. and P. Pelet, "Modes in chirowaveguides," Opt. Lett., Vol. 14, No. 11, 593-595, 1989.
doi:10.1364/OL.14.000593

4. Herman, W. N., "Polarization eccentricity of the transverse field for modes in chiral core planar waveguides," J. Opt. Soc. Am. A, Vol. 18, No. 11, 2806-2818, 2001.
doi:10.1364/JOSAA.18.002806

5. Pelet, P. and N. Engheta, "The theory of chirowaveguides," IEEE Trans. Antennas Prop, Vol. 38, No. 1, 90-98, January, 1990.
doi:10.1109/8.43593

6. Demidov, S. V., K. V. Kushnarev, and V. V. Shevchenko, "Dispersion properties of the modes of chiral planar optical waveguides," J. Comm. Tech. Electron., Vol. 44, 827-832, 1999.

7. Bahar, E., "Mueller matrices for waves reflected and transmitted through chiral materials: Waveguide modal solutions and applications," J. Opt. Soc. Am. B, Vol. 24, 1610-1619, 2007.
doi:10.1364/JOSAB.24.001610

8. Herman, W. N., "Amorphous thin films of chiral binaphtyls for photonic waveguides," J. Macromol. Sci., Part A, Pure Appl. Chem., Vol. 40, No. 12, 1369-1382, 2003.
doi:10.1081/MA-120025316

9. Guy, L., T. Vautey, and S. Guy, "The use of LCMS as an analytical tool for hydrolysis/polycondensation monitoring of a chiral ormosil precursor," Sol. Gel. Science Technologie, Vol. 52, 146-152, 2009.
doi:10.1007/s10971-009-2004-4

10. Guy, S., L. Guy, A. Bensalah, A. Pereira, V. Grenard, O. Cosso, and T. Vautey, "Pure chiral organic thin films with high isotropic optical activity synthesized by UV pulsed laser deposition," J. Mater. Chem., Vol. 19, 7093-7097, 2009.
doi:10.1039/b908104f

11. Lambeck, P. V., "Integrated optical sensors for the chemical domain," Meas. Sci. Technol., Vol. 17, No. 8, R93-R116, 2006.
doi:10.1088/0957-0233/17/8/R01

12. Lukosz, W., "Principles and sensitivities of integrated optical and surface plasmon sensors for direct affinity sensing and immunosensing," Biosensors and Bioelectronics, Vol. 6, No. 3, 215-225, 1991.
doi:10.1016/0956-5663(91)80006-J

13. Tiefenthaler, K. and W. Lukosz, "Sensitivity of grating couplers as integrated-optical chemical sensors," J. Opt. Soc. Am. B, Vol. 6, No. 2, 209-220, 1989.
doi:10.1364/JOSAB.6.000209

14. Lindell, V. I., A. Shivola, S. A. Tretyakov, and A. J. Viitanen, Electromagnetic Waves in Chiral and Bi-isotropic Media, Artech House, 1994.

15. Yariv, A. and P. Yeh, Optical Waves in Crystals, Wiley, New York, 1984.

16. Pelet, P. and N. Engheta, "Coupled-mode theory for chirowaveguides," J. Appl. Phys., Vol. 67, No. 6, 2742-2745, 1990.
doi:10.1063/1.345439

17. Parriaux, O. and G. J. Veldhuis, "Normalized analysis for the sensitivity optimization of integrated optical evanescent-wave sensors," J. Lightwave Technol., Vol. 16, No. 4, 573-582, 1998.
doi:10.1109/50.664066

18. Horvath, R., L. R. Lindvold, and N. B. Larsen, "Reverse-symmetry waveguides: Theory and fabrication," Appl. Phys. B, Vol. 74, 383-93, 2002.
doi:10.1007/s003400200823

19. Lukosz, W., "Integrated optical chemical and direct biochemical sensors," Sensors and Actuators B, Vol. 29, 37-50, 1995.
doi:10.1016/0925-4005(95)01661-9

Prof. Stephan Guy

Dr. A. Bensalah-Ledoux

Dr. A. Stoita