Micro-lens arrays were adopted to homogenize the beam profile of 532-nm pumping laser for the main amplifier of an intense femtosecond, chirped pulse amplification (CPA) Ti:sapphire laser. Experimental measurements showed a great improvement of the near-field pattern of the CPA beam after the main amplifier and the size of the focal spot was improved from 2.7 times diffraction limitation (DL) to 1.6 DL. The spot size focused by an f/4 off-axis parabola (OAP) in the target chamber was measured to be 5.8 micron (full-width at half-maximum (FWHM)), and a peak intensity of 2.6*10^(20) W/cm2 was obtained at the output power of 120 TW. Peak intensity exceeding 10^(21) W/cm2 or even 10^(22) W/cm2 can be expected with smaller f-number focusing configuration and wavefront correction.
© 2006 Chinese Optics Letters
(140.3300) Lasers and laser optics : Laser beam shaping
(140.3590) Lasers and laser optics : Lasers, titanium
(140.7090) Lasers and laser optics : Ultrafast lasers
(350.3950) Other areas of optics : Micro-optics
Wentao Wang, Yi Cai, Bin Shuai, Wenyao Wang, Yunhua Jiang, Lihuang Lin, Ruxin Li, and Zhizhan Xu, "Beam quality improvement and focused peak intensity measurement of an intense femtosecond Ti:sapphire laser system," Chin. Opt. Lett. 4, 583-585 (2006)