[1] [1] T. L. Yeo, T. Sun, and K. T. V. Gratan, “Fiber-optic sensor technologies for humidity and moisture measurement,” Sensors and Actuators A: Physical, vol. 144, no. 2, pp. 280-295, 2008.

[2] [2] C. Lauer, S. Szalay, G. Bohm, C. Lin, F. Kohler, and M. C. Amann, “Laser hygrometer using a vertical vertical-cavity surface-emitting laser (VCSEL) with an emission wavelength of 1.84 μm,” IEEE Transactions on Instrumentation and Measurement, vol. 54, no. 3, pp. 1214-1218, 2005.

[3] [3] W. Jin, H. F. Xuan, and H. L. Ho, “Sensing with hollow-core photonic bandgap fibers,” Measurement Science and Technology, vol. 21, no. 9, pp. 4014-4026, 2010.

[4] [4] Y. L. Hoo, S. Liu, H. L. Ho, and W. Jin, “Fast response microstructured optical fiber methane sensor with multiple side-openings,” IEEE Photonic Technology Letters, vol. 22, no. 5, pp. 296-298, 2010.

[5] [5] J. Mathew, Y. Semenova, G. Rajan, and G. Farrell, “Humidity sensor based on photonic crystal fiber,” Electronic Letters, vol. 46, no. 19, pp. 1341-1343, 2010.

[6] [6] L. S. Rothman, I. E. Gordon, A. Barbe, D. C. Benner, P. F. Bernath, M. Birk, et al., “The HITRAN database 2008 molecular spectroscopic database,” Journal of Quatitative Spectroscopy and Radiative Transfer, vol. 110, no. 2, pp. 533-572, 2009.

[7] [7] A. Ray, A. Bandyopadhyay, B. Ray, D. Biswas, and P. N. Ghosh, “Line-shape study of water vapor by tunable diode laser spectrometer in the 822-832 nm wavelength region,” Applied Physics B: Lasers and Optics, vol. 79, no. 7, pp. 915-921, 2004.

[8] [8] H. Wang. Q. Wang, J. Chang, X. Zhang, S. Zhang, and J. Ni, “Measurement technique for methane concentration by wavelength scanning of a distributed-feedback laser,” Laser Physics, vol. 18, no. 4, pp. 491-494, 2008.

[9] [9] A. M. Cubillas, J. M. Lazaro, M. Silvo-Lopez, O. M. Conde, M. Petrovich, and J. M. Lopez-Higuera, “High sensitive methane sensor based on a photonic bandgap fiber,” presented at Third European Workshop on Optical Fiber Sensors (EWOFS 2007), Napoli, Italy, 2007.

[10] [10] T. Ritari, J. Tuominen, and H. Ludvigsen, “Gas sensing using air-guiding photonic bandgap fibers,” Optics Express, vol. 12, no. 17, pp. 4080-4087, 2004.

[11] [11] W. Demtroder, Laser Spectroscopy: Basic Concepts and Instrumentation. New York: Springer, 1993, pp. 369-372.