Abstract: Controlling a low-threshold femtosecond supercontinuum (fs SCG) in a bulk nonlinear material (BNLM) with a positive thermo-optic coefficient (dn/dT>0 K?1) is provided by coupling light at a first wavelength output by a fs oscillator at a full pulse repetition PRR into the BNLM. The coupling of light produces a nonlinear lens of the coupled beam in the BNLM which is insufficient to provide intensity of the light sufficient to reach ta threshold of the fs SCG. To raise the pulse energy and reach the SCG threshold, light at a second wavelength different from the first wavelength is absorbed in the BNLM to form a thermal lens in the BNLM which assist the nonlinear lens in creating the SCG.