عنوان مقاله [English]
نویسندگان [English]چکیده [English]
A self-filtering unstable resonator (SFUR)with a magnification of M=-3 in a Nd:YAG(2ω)dye laser has been studied.The dye solution is Rhodamine 6G in alcohol with theconcentration of 5 ×10 -3 Mol/lit. The spatial intensity distribution of the resonator has been compared with that of a plane-parallel (PP) resonator of equal length. The output energy in both configurations are comparable (20 μЈ ,and 26μЈ ,respectively). A significant difference between these two resonators is the laser beam divergence, where beam divergences of 0.77 mrad for the SFUR and 1.6mrad for the plane-parallel resonator have been measured. The brightness corresponding to these two resonators are 1.5× 1011 and 2.2× 1010 W.cm-2.Sr-1, and the pulse widths are 7 and 17 ns, respectively. These figures show clearly that laser resonator based on the SFUR design can increase the laser brightness by a factor of 10,with a beam divergence of a fraction of mrad, compared with the plane-parallel resonator. In order to describe the dynamic behavior of the SFUR design, a numerical calculation based on the rate equations have been used and a good consistency with the experiment has been obtained.
1. A. E. Siegman , “Laser,” University Science Books, Ca. (1986).
2. A. E. Siegman ,”Stabilizing out put with unstable resonator,” Laser Focus 7, 42 (1971).
3. A. E. Siegman, “Unstable optical resonators,” Appl. Optics 13, 353 (1974).
4. A. E. Siegman and R. W. Arrathon, “Modes in unstable optical resonstors and lens waveguides,” IEEE J.Quant. Electr. QE-3, 156 (1967).
5. P. G. Gobbi and G. C. Reali, “A novel unstable resonator configuration with a self filtering aperture,” Optics Commu. 52, 195 (1984).
6. R. Barbini, A. Ghigo, M. Giorgi, K. N. Iyer, A. Palucci and S. Ribezzo, “Injection-Locked single-mode high-power low-drivergence TEA CO2 laser using SFUR configuration,” Optics Commu. 60, 239 (1986).
7. R. Bhatnagar, S. K. Dixit, B. Singh and S. V. Nakhe, “Performance of a copper vapor laser with self-filtering unstable resonator,” Optics Commu. 74, 93 (1989).
8. P. Di Lazzaro, T. Hermsen, T. Letardi and C. E. Zheng, “Self-filtering unstable resonator: An approximate analytical model with comparison to computed and XeCl laser experimented results,” Optics Commu. 61, 393 (1987).
9. V. Boffa, P. Di Lazzaro, G. P. Gallerano, G. Girodano, T. Hermsen, T. Letardi and C. E. Zheng, “Self-filtering unstable resonator operation of XeCl Excimer laser,” IEEE J.Quant. Electr. QE-23, 1241 (1987).
10. P. Di Lazzaro, V. Nassisi and M. R. Perrone, “Experimental study of a generalized self-filtering unstable resonator applied to an XeCl laser,” IEEE J.Quant.Electr. QE-24, 2284 (1988).
11. M. R. Perrone and A. A. Flippo, “Experimental characterization of high magnification self-filtering unstable resonators for XeCl laser,” Optics Commu. 88, 115 (1992).
12. J. W. Chen, A. Luches, V. Nassisi and M. R. Perrone, “High brightness single transverse mode operation of a XeCl laser,” Optics Commu. 72, 225 (1989).
13. Li Ho Min and K.Vogler, “Confocal positive branch-filtering unstable resonator for Nd:YAG-Laser,” Optics Commu. 74, 79 (1989).
14. A. H. Farahbod and A. Hariri, “Application of generalized self-filtering unstable resonators to a N2-Laser pumped dye laser,” Optics Commu. 108, 84 (1994).
15. M. Mahmodi, A. H. Farahbod and A. Hariri, “Experimental study of generalized self-filtering unstable resonators in an ablative-wall flash-lamp-pumped dye laser,” Appl.Optics 37, 1053 (1998).
16. A. H. Farahbod, B. Daneshvar, and A.Hariri, “Performance of Nd:YAG laser in coupled generalized self-filtering and positive-branch unstable resonators,” Appl. Optics. 38, 4516 (1999).
17. A. H. Farahbod, PhD Thesis, Amirkabir University, p84 (1376).
18. B. B. Snavely, “Flashlamp-excited organic dye lasers,” Proc. IEEE 57, 1374 (1969).
19. P. R. Hammond, “Spectra of the lowest excited singlet states of Rhodamine 6G and Rhodamine B,” IEEE J.Quant. Electr. QE-15, 624 (1979).
20. L. G. Nair, K. Dasgupta, “Amplified spontaneous emission in narrow-band pulsed dye laser oscillators-theory and experiment,” IEEE J. Quant. Electr. QE-21, 1782 (1985).
21. U. A. Ganiel, G. Neumann and D. Treves, “Amplified spontaneous emission and singnal amplification in dye laser systems,” IEEE J. Quant. Electr. QE-11, 881 (1975).
22. D. U. Von Rosenberg, “Methods for the numerical solution of partial differential equations,” New York, Elsevier (1969).