Femtosecond pulse compression by second-harmonic generation in aperiodically poled KTP

Summary form only given. In this paper we describe the use of an aperiodically poled crystal of KTiOPO/sub 4/ (KTP) to frequency double and compress the direct output from a femtosecond optical parametric oscillator (OPO) running at a wavelength of 1.25 /spl mu/m. The OPO produced dispersion-broadened 286-fs signal pulses with a bandwidth of 37 nm (six times transform limited) at an average output power of 530 mW at 1.25 /spl mu/m.