Abstract

Promising new ideas in few-cycle pulse technology or attosecond physics depend on the availability of two precisely synchronized mode-locked pulse trains. Specific examples include the generation of pulses with zero carrier-envelope-phase slip by difference frequency mixing or the coherent combination of different stabilized laser spectra. These applications require a mutual timing jitter of less than one tenth of an optical cycle. Such high degree of synchronization with two separate laser systems has been achieved by sophisticated electronic stabilization with a bandwidth ranging as high as the Nyquist frequency. On the other hand, we have recently presented a novel approach towards the generation of potentially extremely precisely synchronized femtosecond pulse trains. The design employs two parallel Enfiber amplifier branches seeded by a single mode-locked Enfiber oscillator. While the amplifiers share a common seed source, they may be configured independently in terms of output wavelengths and pulse characteristics. Implementation of this system for optical frequency metrology has already demonstrated the advantages of the two-branch design [1]. However, these experiments do not allow to predict whether the level of phase coherence is sufficient for the high demands of time-domain applications, which are extremely susceptible to absolute phase differences.

© 2007 IEEE