Spectral characteristics of ultrashort pulses in Kerr-lens - TU Wien

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1r a 700 800 900 1000 ,nm b 10_i io2 ____________________________________ 750 800 850 900 950 ?L, nm C . . -20 2 gain cross-section, 10 cm 700 800 900 1000 1100 Figure 3. Ground-state absorption of Cr:LiSGaF (a), round-trip resonator losses due to the output coupler (b) and gain cross-section of Cr:LiSGaF (c). the cavity configuration, which is a common procedure for Kerr-lens mode-locking experiment. Another fundamental factor in our model is the presence of high-order dispersions due to the active medium, the dispersion compensator, the output coupler, and high-reflective mirrors. The corresponding experimental characteristics are shown in Fig. 2. For the numerical calculations, the data were represented by the eighth-order polynomial approximation. The action of dispersion can thus be presented in the following form: a(z,t) =f a(z,t' )G(t — t')dt', (1) G(t — t') = exp (_ Dj(w — w0) — (t — t') dw, (2) where w is the frequency, G(t — t') is the Green's function depending on the dispersion coefficients D3 up to eighth order of j. The next important factor in our model is the gain saturation that was described on the basis of quasi-two level scheme of the active medium operation 12: — 1p014 al2 o32 a — (amax — a) — a — — Dt hi' hi' (3) Tr 16 Proc. SPIE Vol. 4752 Downloaded From: http://spiedigitallibrary.org/ on 04/12/2013 Terms of Use: http://spiedl.org/terms
iii C') a) CC' C) a) a- C,) 750 800 850 900 950 1000 Wavelength, nm Figure 4. Experimental demonstration of the pulse frequency shift. The output spectra of modelocked Cr:LiSGaF laser, with changing intracavity pulse peak power (bottom spectrum corresponds to the lowest peak power, top spectrum - to the highest peak power). (9 E C) C Co C) C CO E Co 100 200 300 400 500 600 700 Raman shift, cm Figure 5. Raman gain of undoped LiSGaF. Exciting laser line at 514.5 nm and scattered light are both polarized along the crystallographic z axis, corresponding to the polarization of the laser radiation in Cr:LiSGaF laser. Proc. SPIE Vol. 4752 17 Downloaded From: http://spiedigitallibrary.org/ on 04/12/2013 Terms of Use: http://spiedl.org/terms
Page 1 and 2: Spectral characteristics of ultrash
Page 3: dispersion, fs2 chirped mirrors 0 -
Page 7 and 8: = (11) = (12) It should be noted, t
Page 9 and 10: a group-delay 2 dispersion, fs 0 -1
Page 11 and 12: rLe in Fig. 7 Px104 ti,, fs E, nJ s
Page 13: 9. LT. Sorokina, E. Sorokin, E. Win

Spectral characteristics of ultrashort pulses in Kerr-lens - TU Wien

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