Practical devices for measuring extremely short and extremely long pulses

Measuring extremely short (few fs) pulses conveniently remains a challenge mainly due to group velocity mismatch (GVM) in the required extremely thin nonlinear crystal and also geometrical effects that require an extremely small beam crossing angle. In this work, we overcome all of these difficulties to build relatively simple devices based on frequency resolved optical gate (FROG) for both types of pulses. We achieved a /spl sim/20 ps delay range in a single-shot geometry by crossing two line-focused beams at a 50/spl deg/ angle, which still allows phase-matching in the crystal.