[1] [1] S. S. Sundaram, S. S. Negi, A. K. Sahay, N. Kandpal, and E. Altaf, Bulletin of Defence Research and Development Organisation. 16, 1 (2008).

[2] [2] C. Fan, Z. Wang, L. Lin, M. Zhang, and H. Fan, Chin. Phys. Lett. 24, 1973 (2007).

[3] [3] H. Deng, J. Liu, and Z. Chen, Chin. Opt. Lett. 8, 24 (2010).

[4] [4] M. N. Abedin, I. Bhat, S. D. Gunapala, S. V. Bandara, T. F. Refaat, S. P. Sandford, and U. N. Singh, in Proceedings of Advanced Research Workshop-Future Trends in Microelectronicsl: Up the Nano Creek 1 (2006).

[5] [5] J. Fan, Infrared and Laser Engineering (in Chinese) 5, 536 (2006).

[6] [6] H. Schneider, T. Maier, J. Fleissner, M. Walther, P. Koidl, G. Weimann, W. Cabanski, M. Finck, P. Menger, W. Rode, and J. Ziegler, Electron. Lett. 40, 831 (2004).

[7] [7] H. M. Huang and C. K. Chiang. Proc. SPIE 3374, 370 (1998).

[8] [8] Q. Sun, B. Yu, Z. Wang, G. Mu, and Z. Lu, Acta Phys. Sin. (in Chinese) 53, 756 (2004).

[9] [9] T. D. Rahmlow, J. E. Lazo-Wasem, S. Wilkinson, and F. Tinker, Proc. SPIE 6940, 1 (2008).

[10] [10] Y. Peng, X. Wei, and W. Wang, Chin. Opt. Lett. 9, 061403 (2011).

[11] [11] I. T. Sorokina and K. L. Vodopyanov, Solid-state Mid-Infrared; Sources (Springer-Verlag, Berlin, 2003) pp.445-462.

[12] [12] W. Luo, S. Yuan, B. Yan, Q. Lu, and Q. Zou, Chin. Opt. Lett. 9, 081403 (2011).

[13] [13] R. S. Ram, Z. Morbi, B. Guo, K. Q. Zhang, P. F. Bernath, J. V. Auwera, J. W. Johns, and S. P. Davis, Astrophys. J. (Suppl.) 103, 247 (1996).

[14] [14] A. A. Klein, H. Vigue, and C. Chardonnet, J. Mol. Spectrosc. 228, 206 (2004).