We demonstrate a compact Ti:sapphire oscillator with ring cavity configuration.By optimizing the intra-cavity dispersion with chirped mirrors,pulses with repetition rate of 1.1 GHz are coupled out by the uncoated wedges in the cavity.Under 7W CW pump laser centered at 532 nm,the average power of the output pulses is about 30 mW,the duration is less than 10fs and the spectrum spans from 670 nm to 920 nm.
A compact femtosecond Ti:sapphire laser resonator consisting of three chirped mirrors and one output coupler was designed. By accurately balancing the intra- cavity dispersions between Ti:sapphire crystal, air and chirped mirrors, we directly generated the laser pulse shorter than 7 fs at the average power of 340 mW with 3.1 W pump. The repetition rate of the laser oscillator is 173 MHz at the centre wavelength of 791 nm, and the ultrabroaden spectrum covers from 600 nm to 1000 nm. To the best of our knowledge, this is the simplest laser resonator capable of generating sub-10 fs laser pulse.
We demonstrate the interference phenomenon in the White Light Continuum(WLC) generated by a single femtosecond laser beam. Different kinds of spatial interference patterns of the WLC generation under various conditions were investigated. The spatial patterns were attributed to interference between the filaments in the WLC generated by the fundamental laser beam yielding the diffraction effect from spatial confinement. Simulations of different patterns were performed. By comparing the results of simulation with those of experiments,the distances of several micrometers between the neighboring filaments can be derived,which agree with the literature values from direct measurements.
YU ZhiHao & WENG YuXiang Laboratory of Soft Matter Physics,Institute of Physics,Chinese Academy of Sciences,and National Laboratory of Condensed Matter Physics,Beijing 100190,China
