Supercontinuum coherence degradation dominated by the injected pulse duration and soliton collision under shot noise

Previous studies have shown that supercontinuum (SC) coherence degradation induced by shot noise can be quantitatively assessed through the injected soliton order, and the degradation process mainly originates from the noise amplification via the modulation instability effect. However, this still cannot clarify the irregular distribution property of SC coherence when the injected soliton order is between 10 and 30. In this paper, we present both theoretical analyses and numerical simulations of SC coherence degradation under shot noise on the premise of a fixed SC span. Our studies clearly show that the injected pulse duration is the dominant factor of SC coherence under the shot noise. In addition, as an auxiliary mechanism, soliton collision can further degrade the SC coherence, and the collision probability becomes greater with the increase of injected soliton order.