24 10 2004 10 : 025322239 (2004) 102133025 ACTA OPTICA SINICA Vol. 24,No. 10 October, 2004 3 1,2 1,2 3 3 1 1 1 3 3 3 1, 201800 2, 100039 3, 200030 : (,PPLN),,,,,, 20 mm, 6. 5m, 0. 5 mm, : ; ; ; : TN722 : A Exp e ri me nt al I nves tiga ti on of Q uasi2cw Fre que ncy2doubli ng of B r oa d B a nd Fi be r L as e r i n Pe ri odically Pole d Lit hi um Ni oba t e Zhu Xiaozheng 1,2 Zhou J un 1,2 Lou Qihong 1 Dong J ingxing 1 Wei Yunrong 1 Chen Xianfeng 3 Xia Yuxing 3 Chen Lijun 3 1 Sha nghai Institute of Optics & Fi ne Mecha nics, The Chi nese Academy of Sciences, Sha nghai 201800 2 Graduate School of the Chi nese Academy of Sciences, Beiji ng 100039 3 Dep a rt ment of Applied Physics, Sha nghai J i aotong University, Sha nghai 200030 (Received 18 April 2003 ; received 6 February 2004) Abs t ract : Develop ments in double clad fiber lasers, coupled with engineered nonlinear optical materials s uch as periodically p oled lithium niobate ( PPLN), are opening a way f or a w hole new class of p ractical nonlinear optical devices. Temperature characteristic and spectra characteristic of second harmonic generaration ( SHG) in PPLN using quasi2cw broad band fiber laser have been investigated. The central f undamental wavelength dependence of PPLN temperature and the temperature FWHM p hase2matching bandwidth were theoretically studied. The f undamental wavelength FWHM p hase2matching of PPLN was calculated too. The 20 mm long PPLN with 6. 5m p oling period and 0. 5 mm thick was used for doubling frequency of the quasi2cw broad fiber laser. The spectra of second harmonic at different temperature are achieved and discussed in detail. Key w or ds : laser techniques ; periodually p oled lithium niobate ; fiber laser ; doubling frequency 3 (103341101) (036105034) 3 3 E2mail : lzlx @263. net :2003204218 ; :2004202206
10 : 1331 1 [4, ],,,,, [1,2 ],,,, (QPM),,,,,,, [3 ] : 2, LiNbO 3 m m = m= 2 ml c = (PPLN) KTP ( PPKTP) 2 ( n 2- n), (1) LiTaO 3 (PPLT), :, m, n n 2,, ; LiTaO 3 ( PPLT), [5, ],, [6,7 ] : n 2 e = 5. 35583 + 4. 629 10-7 0. 1004 + 3. 862 10-8 F F + 2 - (0. 20692-0. 9 10-8 F) 2 + 100 + 2. 657 10-5 F 2-11. 34927 2-1. 5334 10-2 2, (2) no 2 0. 11775 + 2. 2314 10-8 f = 4. 9048 + 2 - (0. 21802-2. 9671 10-8 F) 2 + 2. 1429 10-8 f - 0. 027153 2, (3) (2) F = ( T - 24. 5 ) ( T + 570. 82 ), (3) K = K 2-2 K- 2, f = ( T - 20 ) ( T + 20 + 546 ), F f = 2n 2-2 n 1-2. (5), T nn 2,,, m,,, 1,= 6. 5m, 20 mm, 32L 2 d 2 33 I = nn 2 I 2 sinc 2 KL, (4) 2 2c 0 2, L, d 33, 2, c, 0, I 10-6 / [8] 1. 054,K : 16. 7 1. 068m, 86. 9235. 9, [9] 100240
1332 24 Fig. 1 Dependence of the temperature of PPLN on the fundamental wavelength 2 = 6. 5m, 20 mm Fig. 3 Dependence of the second harmonic normalized efficiency on fundamental wavelength 1. 064m, 197. 5, 0. 98 3 4 : Yb 197. 5,, 0. 15 nm, 1. 064m, [9 ] 0. 12 nm 1 2 3 20100 khz, I (e2e e) Fig. 2 Dependence of the second harmonic normalized efficiency on temperature of the PPLN 3 6 nm, 010 W, 10 mm, f = 750 mm L 1 f = 10 mm L 2, 1 mm,, (PBS), 1 mm L 3,,, 30230, 0. 1 20 mm, 0. 5 mm, 6. 5m L 4, Fig. 4 Schematic diagram of experimental configuration 4 23,, 0. 15 nm, [9 ] 0. 12 nm 1 nm,, [9,10 ], CCD, Yb,, 5 5 197, 3,, 0. 4 nm 23, 1. 2 nm
10 : 1333,, : ; 6. 5m 6. 51m 0. 521 nm 0. 01m,, Fig. 5 Spectra of fundamental2wave laser :,,, 6. 5m, 6,, 6, 6 225 mw, : 23, 193. 1,,, 8. 2 mw 7, :,, 193. 1 197. 2 200. 8 2 1 1064 nm,, 197. 5 197. 2,,,, 5,, 193. 1 200. 8,, 5,193. 1,200. 8,197. 2, Fig. 6 Spectra of second harmonic at different temperature Fig. 7 The dependence of the energy of second harmonic on PPLN temperature
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