CEP4 is Femtolasers' latest generation of Carrier Envelope Phase (CEP) stabilisation techniques.

Via a direct feed-forward approach, the CEP drift is corrected on-the-fly after the free-running passively stable femtosource rainbow ultrafast oscillator. Zero phase slip, a train of pulses with identical waveform, is now as easy to obtain as any other slip rate.

Reliability is ensured by the CEP4 stabilisation operation. The CEP4 approach is packaged in a compact and robust module available together with the femtosource rainbow oscillator.