Single Color Event Horizon in a Photonic Crystal Fibre

The nonlinear interaction of an intense solitonic pulse with a weak probe pulse may give rise to an optical analogue of an event horizon (EH) [1,2], recently used to demonstrate the possibility to generate Hawking-like radiation in the laboratory setting [3]. To realize this situation, both the soliton and the weak dispersive wave (DW) are required to propagate with near-identical group velocities. However, the experimental prerequisites are difficult to be realized. One needs two synchronized laser pulses at group velocity matched wavelengths, ultrashort pulses in the sub-10 fs are required [3], which may underlie strong perturbations, e.g., by the Raman effect, and all previously proposed schemes only allow very short interaction lengths. Here, we present a method which overcomes all these constraints and inherently generates the EH. By pumping a single-color strong DW group- and phase-matched solitons are created at the leading edge by means of an optical shock wave [3,4]. The solitons do not only meet the above constraints, but also ensure huge interaction lengths, even supported by the Raman effect. We investigate the dynamics numerically in detail and provide experimental evidence.