Generation of a MW-class tunable Raman soliton up to 3.8 µm in a fluorotellurite fiber

We report the generation of MW-class tunable Raman solitons of 3.3-3.8 µm in a fluorotellurite fiber. The pump source of the mid-infrared fiber is a 2.15-2.3 µm Raman soliton source which has the highest peak-power Raman soliton (3.8 MW) ever achieved in a silica fiber. Fluorotellurite fiber is characterized by its short length and high nonlinearity, preventing the Raman soliton pulse broadening that occurs with fiber dispersion. The Raman soliton shifted to 3.8 µm while still maintaining an ultra-narrow pulse width of 70.4 fs with 1.36 W output power and 1.17 MW peak power. To the best of our knowledge, this is the highest peak-power Raman soliton obtained in a mid-infrared fiber.