ACTA OPTICA SINICA ,,, , ,

Transcription

1 : (2004) ACTA OPTICA SINICA Vol. 24,No. 10 October, ,2 1, , , , : (,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 Graduate School of the Chi nese Academy of Sciences, Beiji ng Dep a rt ment of Applied Physics, Sha nghai J i aotong University, Sha nghai (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 ( ) ( ) 3 3 E2mail : net : ; :

2 10 : [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 = F F ( F) F , (2) no f = ( F) f , (3) (2) F = ( T ) ( T ), (3) K = K 2-2 K- 2, f = ( T - 20 ) ( T ), 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] ,K : m, , [9]

3 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 m, , : Yb ,, nm, m, [9 ] nm 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, mm, 0. 5 mm, 6. 5m L 4, Fig. 4 Schematic diagram of experimental configuration 4 23,, nm, [9 ] nm 1 nm,, [9,10 ], CCD, Yb,, , 3,, 0. 4 nm 23, 1. 2 nm

4 10 : 1333,, : ; 6. 5m 6. 51m nm 0. 01m,, Fig. 5 Spectra of fundamental2wave laser :,,, 6. 5m, 6,, 6, mw, : 23, ,,, 8. 2 mw 7, :,, nm,, ,,,, 5,, ,, 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

5 , 4 Taverner D, Britton P, Smith P G R et al.. Highly efficient second2harmonic and sum2freuency generation of nanosecond pulse, in a cascaded erbium2doped fiber : periodically poled lithium, 5 Wang Zhijian, Yang Jiaxiang. The study of photorefractive effect Edition) ( ), 1997, 21 (4) : 27, 33 (in Chinese), 6 Jundt D N. Temperature2dependent Sellmeier equation for the, index of refraction, n e, in congruent Lithium niobate. Opt. Lett., 1997, 22 (20) : , 1 Zhou Jun, Lou Qihong, Li Tiejun et al.. A 4. 9 W CW ytterbium2doped double2cladding fiber laser and its output characteristics. Acta Optica Sinica ( ), 2003, 23 (4) : (in Chinese) 2 Qihong Lou, Jun Zhou, Jianqiang Zhu et al.. 502watt ytterbium2 doped double2clad fiber laser. Chin. Opt. Lett., 2003, 1 (10) : Liang Xiaoyan, Hou Wei, Lu Junhua et al.. Lowthreshold wide tunable PPLN optical parametrical oscillator. Chin. J. Lasers ( ), 2002, A29(1) : 1012 (in Chinese) niobate source. Opt. Lett., 1998, 23 (3) : in LiNbO 3 and LiTaO 3. J. Anhui Uinversity ( Natural Science 7 Edwards G J, Lawrence M. A temperature2dependent dispersion equation for congruently grown Lithium niobate. Opt. Quant. Electron., 1984, 16 (4) : Sang Mei, Xue Ting, Yu Jian et al.. Temperature dependence of the second harmonic generation in periodically poled LiNbO 3 crystal. J. Optoelectronics &Laser ( ), 2002, 14 (4) : (in Chinese) 9 Guskov S A, Popov S, Chernikov S V et al.. Second harmonic generation around m of seeded Yb fibre system in periodically poled lithium niobate. Electron. Lett., 1998, 34 (34) : Champert P A, Popov S V, Taylor J R. Highly, variable pulse format 770 nm sourse based on powerful seeded generation in periodically poled KTP. Electron. Lett., 2000, 36 (7) :