1484-nm two-cascaded Raman fiber laser mode-locked by an intermode-beating mode-locking technique

Abstract

We demonstrate a 1484-nm two-cascaded Raman mode-locked fiber laser based on the intermodebeating mode-locking (IBML) technique. Through the two-cascaded Raman shifts of P 2 O 5 in a phosphosilicate fiber, the continuous-wave (CW) 1064-nm Raman pump can be transferred to the 1484-nm second-order Stokes. When the intermode-beating frequency of the 1064-nm pump source matches with the 1484-nm Raman-cavity frequency, the IBML condition is satisfied, and the harmonic mode-locking at 1484-nm occurs to stably emit nanosecond pulse trains. By properly adjusting the 1484 nm Raman-cavity length, we have further realized the tuning of the mode-locking harmonic order. The 472nd-and 757th-order harmonic mode-locking operations with repetition rates of 72.728 and 116.292 MHz have been obtained, respectively. The IBML operation is stable with a radio-frequency (RF) supermode suppression ratio of 33.9 dB and RF signal-to-noise ratio of 51.8 dB.