Time-domain aspect of carrier-envelope-phase control; Field stabilized optical pulse generation

摘要

An ultrashort pulse laser system with precisely controlled output-timing and carrier-envelope phase (CEP) is reported. Recently developed technology on CEP control of a mode-locked laser not only introduced an optical frequency comb in frequency domain but also gave us a way to generate optical pulses whose oscillating electric field is under a fixed phase relation with the intensity shape. Fortunately, recent advances on optical physics have also showed that some types of light-matter interactions become sensitive to the field shape when the pulse approaches a few cycles in duration and has a high peak intensity. Owing to those advances, field-controlled ultrashort pulse generation, based on sub-femtosecond resolution timing-control and sub-radian CEP control of femtosecond lasers, becomes an attractive challenge. Our final goal is to realize a shaped electric field within optical-cycle time scale for researches on light-matter interaction and other future application. CEP control on a mode-locked Ti:sapphire laser is the first step of such a laser system. Trade-off between the accuracy and robustness of the control, and the monitoring technique of CEP for amplification, will be discussed. Amplification of a CEP-controlled pulse, which is necessary for most of lime-domain application, is successfully performed by the CEP monitoring technique. Our chirped-pulse amplifier, that includes a grating-based stretcher/compressor, has a potential to achieve higher-energy amplification of a fixed CEP pulse. Multichannel phase control of spectrally divided ultrashort pulses is applied to dynamic control of pulse-timing and CEP of amplified pulses. Related results on short-pulse, sub-13fs, generation by a chirped-pulse Ti:sapphire amplifier, and multicolor phase-coherent pulse sources will be also discussed briefly, showing our on-going efforts to approach the final goal.