我們建造了一台腔長為7 cm的1009 nm外腔式錐形放大器雷射，此雷射的功率可以高達1.2 W，波長可調範圍約為37 nm，且有單頻的特性，很適合做為量測光譜的光源。
接著我們透過週期性極化鈮酸鋰晶體(PPLN)來做二倍頻，得到504.5 nm 的綠光，最後我們使用飽和吸收光譜(saturation absorption spectroscopy)的方法，觀察碘分子的超精細光譜。未來，我們會將雷射鎖頻至碘分子的超精細譜線上，作為氦原子21S0-31D2躍遷絕對頻率量測的頻率標準。

We built a 1009 nm external cavity tapered amplifier Laser with 7 cm long cavity length. The laser have the advantages of high power (1.2 W) , wavelength tunable (37 nm), single mode and narrow linewidth so this laser is very suitable for spectroscopy measurement.
After we finish the laser construction we use a 2.5 cm long periodically poled lithium niobate crystal (PPLN) for the second harmonic generation to get the green light at 504.5 nm. Finally, we successfully observe the hyperfine spectrum of iodine by using the saturation absorption spectroscopy method. In the future, We will lock our laser on one of the iodine hyperfine transitions, and use it as the frequency reference for absolute frequency measurements of the 21S0-31D2 transitions of 3He and 4He atom.

1. D. C. Morton, G. W. F. Drake, and Q. Wu, Can. J. Phys., 2006. 84: p. 83.
2. G. W. F. Drake and Z.-C. Yan., Can. J. Phys., 2008. 86: p. 45.
3. K. Pachucki, Phys. Rev. A, 2006. 74: p. 062510.
4. V. A. Yerokhin and K. Pachucki, Phys. Rev. A, 2010. 81: p. 022507.
5. F. S. Pavone, et al., Phys. Rev. Lett., 1994. 73: p. 42.
6. C. Dorrer, et al., Phys. Rev. Lett., 1997. 78(19): p. 3658.
7. P. C. Paster, et al., Phys. Rev. Lett., 2004. 92: p. 143001.
8. Pei-Ling Luo, Precision Spectroscopy of Singlet States in Atomic Helium. Ph.D. Dissertation, National Tsing Hua University, 2014.
9. J. E. Sansonetti and W.C. Martin, Phys. Rev. A, 1984. 29: p. 159.
10. W. Lichten, D. Shiner, and Z.-X. Zhou, Phys. Rev. A, 1991. 43: p. 1663.
11. K. S. E. Eikema, et al., Phys. Rev. Lett., 1993. 71: p. 1690.
12. S. D. Bergeson, et al., Phys. Rev. Lett., 1998. 80: p. 3475.
13. D. Z. Kandula, et al., Phys. Rev. A, 2011. 84: p. 062512.
14. R. van Rooij, et al., Science, 2011. 333: p. 196.
15. Jun Ye, et al., IEEE Trans. Instrum. Meas., 1999. 48: p. 544.
16. Wang-Yau Cheng, et al., Opt. Lett., 2002. 27(8): p. 571.
17. J. N. Eckstein, A. I. Ferguson, and T.W. Hänsch, Phys. Rev. Lett., 1978. 40: p. 847.
18. Th. Udem, et al., Opt. Lett., 1999. 24: p. 881.
19. D. J. Jones, et al., Science, 2000. 288: p. 635.
20. Th. Udem, R. Holzwarth, and T.W. Hänsch, Nature, 2002. 416: p. 233.
21. Walpole, J.N., Opt. Quant. Electron., 1996. 28: p. 623.
22. http://hcphotonics.com/products.asp?area=1670.
23. http://www.covesion.com/support/covesion-guide-to-ppln.html.
24. G. Boyd and D. Kleinman, J. Appl. Phys., 1968. 39: p. 3597.
25. L. D. Landau and E.M. Lifshitz, Statistical Physics, 1980.
26. W. E. Lamb, J., Phys. Rev. , 1964. 134: p. A1429.
27. F.-L. Hong, et al., J. Opt. Soc. Am. B, 2001. 18: p. 1416.
28. H-M Fang, Studies of Laser Stabilization Using Molecular Iodine. Ph.D. Dissertation, National Chiao Tung University, 2004.
29. S. Gerstenkorn, P. Luc, and J. Verges, Atlas du spectre d'absorption de la molécule d'iode. Laboratoire Aimé Cotton, 1987.
30. C. J. Hawthorn, K. P. Weber, and R.E. Scholten, Rev. Sci. Instrum., 2001. 72: p. 4477.
31. K. Liu and M.G. Littman, Opt. Lett., 1981. 6: p. 117.
32. X. Baillard, et al., Opt. Commun., 2006. 266: p. 609.
33. http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/intfilt.html.