Supercontinuum Generation in Cascaded Raman Conversion

The authors demonstrate the possibilities of supercontinuum formation due to cascaded stimulated Raman scattering in a 1-km long optical fibre with standard transverse dimensions doped with phosphorus pentoxide P2O5. For supercontinuum pumping were used noise-like pulses with variable envelope duration (35 to 150 ps) and different coherence degree (with different levels of stochastic fluctuations which corresponded to different amplitudes of the autocorrelation coherence peak). At the average pumping radiation power of 600 mW, the generated supercontinuum width reached 140 nm. Dependencies of supercontinuum properties upon the noise-like pulse parameters are also presented. It is shown that even upon significant increase of the envelope duration of double-scale pulses (from 36 to 153 ps), the efficiency of nonlinear conversion does not decrease. It is also shown that the width of the emission spectrum can reach 225 nm upon reducing the envelope duration down to 25 ps and increasing the coherence peak up to 40%.