The new Micra-CEP from Coherent generates carrier envelope phase (CEP) stabilised ultrafast laser pulses. It is a flexible broadband laser source for the emerging fields of attosecond research, high harmonic generation, optical clocks and coherent control.

The system combines Coherent’s ultrafast Micra laser with a carrier envelope phase detection module and fast feedback electronics. By active feedback control of the laser, the CEP stabiliser locks the phase velocity of the oscillating light field to the group velocity of the pulse envelope. This means that, the peak of the oscillating electric field can be maximised under the pulse envelope for ultrashort pulses consisting of only a few optical cycles.

At the heart of the CEP module is a non-linear interferometer. This unit uses a photonic crystal fibre to generate an octave-spanning optical spectrum. The red end of this spectrum is frequency doubled and combined with the green end of this same broad spectrum. The resultant beat frequency is sensed by a fast photodetector that provides the CEP feedback signal. After suitable processing, this signal is then used to control a fast cavity mirror actuator inside the Micra laser to control the carrier phase.