Current Status and Future Prospects of “J-KAREN” — High Contrast, High Intensity Laser for Studying Relativistic Laser-Matter Interactions

We present the design and characterization of a high-contrast, petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser system.Two saturable absorbers and low-gain optical parametric chirped-pulse amplification (OPCPA) preamplifier in the double CPA laser chain have improved the temporal contrast to 1.4 x 10 12 on the subnanosecond time scale at 70 terawatt level.Final uncompressed broadband pulse energy is 28 J, indicating the potential for reaching peak power near 600 terawatt.We also discuss the going upgrade to over petawatt level at a 0.1 Hz repetition rate briefly.