The invention relates to an ultra-short high-power light pulse source including a first laser pump source (1), a mode-locking laser oscillator (2) a second laser pump source (4), a wave guide (6) capable of inserting spectral phases into the light pulses, and a compressor (8) capable of generating predetermined spectral phases into the light pulses. According to the invention, the wave guide (6) comprises a means capable of compensating the predetermined spectral phases generated at least by the compressor (8), the second laser pump source (4) being capable of delivering a second pump light flow (5) having a power PL such that the spectral phases generated by the wave guide (6) are opposed or quasi opposed to the predetermined spectral phases generated by the compressor (8) in order to generate compressed ultra-short light pulses (9) at the output of the compressor (8) with a planar or quasi planar spectral phase.