We report on the generation of optical pulses with a nearly one octave-spanning spectrum ranging from 1300 nm to 2500 nm at 1 kHz repetition rate,which are based on intra-pulse difference frequency generation (DFG) inβ-barium borate crystal (β-BBO) and passively carrier-envelope-phase (CEP) stabilized.The DFG is induced by few-cycle pulses initiated from spectral broadening in multiple thin plates driven by a Ti:sapphire chirped-pulse amplifier.Furthermore,a numerical simulation is developed to estimate the conversion efficiency and output spectrum of the DFG.Our results show that the pulses from the DFG have the potential for seeding intense mid-infrared (MIR) laser generation and amplification to study strong-field physics and attosecond science.