Simple scheme for generation of two-color photonic molecules

Soliton molecules are usually understood to be co-propagating soliton pairs with a fixed time delay, as observed, e.g., in dispersion-managed fibers [1]. In contrast to those, two-color photonic molecules consist of two separated subpulses in the frequency domain and a single localized state in the time domain. They have been recently proposed theoretically [2] and demonstrated experimentally [3]. A prerequisite for the observation of such state is a group-velocity matching for the spectrally separated constituents, which can be enabled by suitable dispersion characteristics with at least two domains of anomalous dispersion (A1,A2). We have studied these molecule states under various perturbations [4] revealing unique propagation dynamics due to strong entanglement between the individual subpulses. To generate two-color molecules, input pulses at two incommensurable, group-velocity matched frequencies are required, which is difficult to realize experimentally. Here, we propose a self-generation mechanism in a microstructured waveguide enabled by spectral tunneling and supported by the Raman effect naturally occurring in supercontinuum generation. The generation scheme requires only a one color pumping and the fiber design is optimized for commercially available telecom wavelengths.