[1] L. Yang, J. Yang, and K. Yang, Electron. Lett. 40, 17 (2004).
[2] G. D. Wang, C. Y. Chen, and X. B. Shen, Electron. Lett. 41, 22 (2005).
[3] S. D. Deshpande, M. H. Er, V. Ronda, and P. Chan, Proc. SPIE 3809, 74 (1999).
[4] F. Zhang, C. Li, and L. Shi, Infrared Phys. Technol. 46, 323 (2005).
[5] T. W. Bae, Infrared Phys. Technol. 54, 403 (2011).
[6] H. Deng, J. Liu, and Z. Chen, Chin. Opt. Lett. 8, 010024 (2010).
[7] X. Dong, X. Huang, Y. Zheng, L. Shen, and S. Bai, Infrared Phys. Technol. 62, 36 (2014).
[8] W. Hao, K. Zhang, and Z. Zhan, Chin. Opt. Lett. 10, S21005 (2012).
[9] R. Liu and Z. Jing, Chin. Opt. Lett. 10, 021001 (2012).