Spectral and temporal characteristics of a supercontinuum in tapered optical fibres

The emission spectrum of a femtosecond Ti:sapphire laser broadened in a tapered optical fibre and the shape of its envelope are studied as functions of the waist diameter and the laser power coupled to the fibre. By varying the fibre parameters and characteristics of coupled pulses, the envelope of the broadened emission spectrum can be shaped, which is important in using a femtosecond comb for precision measurements. The results of experimental studies of the temporal structure of a supercontinuum in a tapered fibre obtained by using the sum frequency generation are presented for the first time and theoretically interpreted.