学术报告：Compression of high-energy ultrashort laser pulses through a gas-filled tapered planar waveguide
报告 人：陈世华 副教授
报告时间：
报告地点：九龙湖校区田家炳楼南楼203
摘 要：
High-energy light pulses down to few optical cycles are key to a wide variety of applications, driving a quest for reliable, stable, and cost-efficient lasers and light pulse manipulations. On the laser side, the necessary technology has highly matured. As such for the ultrafast optics community, one of the most interesting challenges concerns how to compress the laser pulse to a desired duration with a nice, focusable spatial mode and a high energy throughput.
To date, there are several compression schemes such as those based on hollow core fibers and filamentation that can lead to pulse durations down to the few-cycle regime. But mostly the output energy is confined within the submillijoule level due to material damage or intensity clamping. In this work, we propose a hollow tapered planar waveguide kept flared forward for compression of high-energy ultrashort laser pulses, primarily motivated by a recent technology focus that claimed that a tapered waveguide triumphs over the ridge and stripe ones when designed for high-power diode lasers [see Nature Photonics 3, 24-25 (2009)]. We demonstrate that, when applying to high-energy ultrashort pulse compression, such a flared-taper configuration has the merit of combining the high output powers with the high beam quality previously not easily attainable in a conventional hollow planar waveguide, thereby defining an intriguing trade-off between pulse compression and energy throughput. With our Ti:sapphire laser of 12 mJ and 40 fs, we obtain an output pulse of energy up to 10 mJ and duration 9.4 fs FWHM with a nice, focusable spatial mode. This corresponds to a reliable terawatt ultrashort tabletop laser source, a necessary tool for probing the dynamics of plasmas in the relativistic intensity regime. 