need help on physics hw regarding YAG lasers please
Need Help On Physics Hw Regarding Yag Lasers Please 1 (86.83 KiB) Viewed 35 times
Need Help On Physics Hw Regarding Yag Lasers Please 2 (62.28 KiB) Viewed 35 times
1. Consider a Nd:YAG laser that is pumped with a diode laser. The configuration of this laser is shown below. Diode laser input Nd:YAG rod 1 cm 5 cm 2 + τ Back mirror Reflectivity=1 Curved mirror Radius of curvature = infinity Reflectivity=0.95 Radius of curvature=10 cm The internal loss is 5% per pass. a. Calculate the small signal threshold gain (Yth) for this laser. b. Now calculate the threshold power (Pth). Pin = 1 In(1) (mpd) ( hump) (A (00,? 2)) 2 RRT 20 where Rand Rare the radii of curvature. o = 2.8 x 10 -20 cm T = 230 us take 0. = mp = 130 um Mpd = nni na Mp4 The energy of the upper laser level is 11417 cm*'. See Fig.10.5 in the text. c. What is the reason for the external curved mirror instead of using the back end of the crystal as the second mirror? 0
12840 12819 12623 12607 12575 12519 12432 12370 11507 (11512) 111423 (11417) 4521 F1 Ho2 Fse 7 'F32 1.06415 m 109 10% 10 1.0644 pm 40% 40% Energy in 10 cm 4500 4440 4055 4034 3933 3924 5 7,99 "1912 2514 (2521) 2461 (2468) 2148 (2147) 2110 (2110) 2028 2029) 2002 (2002) 808.7 nm . 830 192 12 311 200 132 0 (a) (b) 300K (c) 77K FIGURE 10.5. Energy level for neodymium in YAG. (a) Structure of YAG showing the pumping routes with the percentages referring to a purp with a broad spectral output. (b) Details of the maroklaz 300 K showing the danmar translalons, the semiconductor laser pumping route is also shown. (c) Energy levels at 77 K. [Data from Kaminski [25). See also Koechner [24]] 360
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