A single-beam and compression-free optical system for generating carrier-envelope phase-stable (CEP-stable) optical pulses of optical carrier frequency f i from input optical pulses, the input optical pulses having an optical carrier frequency f p and pulse duration τ p , the system comprising: - a birefringent medium (B) -- for receiving, in input, the input optical pulses; and - for providing as output pairs of linearly-polarized pulses (PP), each pair of linearly-polarized pulses (PP) having orthogonal polarization along a first and second directions (E1, E2) with a relative optical group delay at approximatively equal to or greater than the pulse duration (τ p ) of the input optical pulses; - a nonlinear medium (NL) -- for receiving in input the output of the birefringent medium (B); and -- for providing as output the pairs of linearly-polarized pulses (PP) with at least one of the two pulses of each pair that is spectrally broadened; - a transparent dispersive optical system (O) -- for receiving in input the output of the nonlinear medium (NL); and - for providing as output the pairs of linearly-polarized pulses (PP) with total or partial temporal overlap between the two pulses of each pair; - a parametric device (DFG) - - for receiving in input the output of the transparent dispersive optical system (O) ; and - for providing as output a frequency-difference between the frequency components polarized along the first direction (E1) and frequency components polarized along the second direction (E2). - a birefringent medium (B) -- for receiving, in input, the input optical pulses; and - for providing as output pairs of linearly-polarized pulses (PP), each pair of linearly-polarized pulses (PP) having orthogonal polarization along a first and second directions (E1, E2) with a relative optical group delay at approximatively equal to or greater than the pulse duration (τ p ) of the input optical pulses; -- for receiving, in input, the input optical pulses; and - for providing as output pairs of linearly-polarized pulses (PP), each pair of linearly-polarized pulses (PP) having orthogonal polarization along a first and second directions (E1, E2) with a relative optical group delay at approximatively equal to or greater than the pulse duration (τ p ) of the input optical pulses; - a nonlinear medium (NL) -- for receiving in input the output of the birefringent medium (B); and -- for providing as output the pairs of linearly-polarized pulses (PP) with at least one of the two pulses of each pair that is spectrally broadened; -- for receiving in input the output of the birefringent medium (B); and -- for providing as output the pairs of linearly-polarized pulses (PP) with at least one of the two pulses of each pair that is spectrally broadened; - a transparent dispersive optical system (O) -- for receiving in input the output of the nonlinear medium (NL); and - for providing as output the pairs of linearly-polarized pulses (PP) with total or partial temporal overlap between the two pulses of each pair; -- for receiving in input the output of the nonlinear medium (NL); and - for providing as output the pairs of linearly-polarized pulses (PP) with total or partial temporal overlap between the two pulses of each pair; - a parametric device (DFG) - - for receiving in input the output of the transparent dispersive optical system (O) ; and - for providing as output a frequency-difference between the frequency components polarized along the first direction (E1) and frequency components polarized along the second direction (E2). - - for receiving in input the output of the transparent dispersive optical system (O) ; and - for providing as output a frequency-difference between the frequency components polarized along the first direction (E1) and frequency components polarized along the second direction (E2). <EOS>