Tunable two-color soliton pulse generation through soliton self-frequency shift

Tunable optical solitons due to intra-pulse stimulated Raman scattering are well-known for their ultrashort pulse width, superb pulse quality and broadband tunability. Consequently they are suitable for a variety of applications, especially multi-photon microscopy (MPM). Recent progress in MPM demands two-or multi-color excitation to match the absorption peaks of multiple fluorophores. Here we propose a new scheme to generate two-color solitons with each wavelength individually tunable. The wavelength of the most energetic soliton can be easily tuned through energy tuning, while stretching the input pulse width narrows the wavelength separation between the most and the second most energetic solitons. This tunable two-color source may find application in various modalities of MPM.