Proceedings - Viện Vật lý

Advances _________________________________________________________________________________in Optics, Photonics, Spectroscopy and Applications. Aug. 2006, Cantho, VietnamThe parameters for determination of this characteristics under our designedconditions are listed in the Table 1.Using the results from the Table 1, we get the output-input characteristics of ourlaser operating in a free-oscillation mode as Figure 3:E(E Þn ) = 5,7 10 -3 (E in - 17,2) (22)Table 1. Parameters related to characteristics output energy versus input energyParameter Symbol Unit Source ValueWave length m given 1.54Photon energy h 10 -19 J E f 1.987/ 1.29Laser pulse energy at the Q-Switch mode E mJ given 5-8Effectiv absorption section of the laser material g cm 2 [1] 810 -21Output mirror reflectivity R opt - [2] 0.8Output mirror useful loss 1 - - ln (R opt ) 0.223Optical loss 2 , L R - [2] 0.144Total loss (not including Q-switch) - = 1 + 2 0.367Maximum gain G 0 G 0 = 2l g g n 0 0.8Density of ion Er +3 n 0 10 19 cm -3 Catalogue 1Laser rod length l g cm compact 5Laser rod diameter g cm compact 0.3laser rod volume V g cm 3 V g = l g ( 2 g /4 ) 0.3535Threshold inversion density n th 10 19 cm -3 [2] 0.46Initial inversion density n i 10 19 cm -3 [2] 0.9Final inversion density n f 10 19 cm -3 [2] 0.18Ratio output energy and above threshold pump area B mJ Relation (11) 75Zero-order term of the output energy a 0 mJ Relation (12) -98Coefficient of the first-order term of the output energy a 1 - Relation (19) 0.0057Threshold pump area A th - Relation (5) 1.307Pump area correlative with initial inversion density A (E Þn ) - Relation (20) 2.996Laser energy in the free-oscillation mode E (E Þn ) mJ Relation (10) 127Input electrical energy on the discharge capacitance E Þn J Relation (17) 39.3Flashlamp pump pulse duration t p ms - 2.1E out [mJ]120100806040200-20-40-60-80QE - 7S = 2.1msec- 0 10 20 30 40 50 60100E in [J]Figure 3. Characteristics output energy of a erbium QE-7S glass laser with p = 2,1 ms289