light waveform synthesis
For atomic-scale electronic motion control we need to control the steering force on a sub-fs time-scale. So far, the room for sub-cycle tailoring of the light waveform has been modest, with timing of the field oscillations with respect to the pulse peak serving as the only control knob. More flexibility in sub-cycle shaping of the field requires a spectrum stretching beyond an octave. Shaping light waves will permit sculpting the electric force on the electronic time scale for steering electrons in atomic systems and pushing the frontiers of attosecond technology.
We pursue several-octave optical waveform synthesis by coherent broadening of the spectrum of intense few-cycle laser pulses via self-phase modulation. Starting out from our few-cycle NIR sources (FP-1,2,3), this approach has recently resulted in supercontinua of unprecedented bandwidth, spanning from the deep UV to the near IR (250-1000 nm) over more than 2 octaves with comparable spectral intensities. Advanced chirped multilayer mirror technology will provide routes to developing multi-channel synthesizers. Selected bands of a coherent several-octave supercontinuum can be further amplified by an OPA chain pumped at different wavelengths ranging from the infrared to near-infrared and visible spectral range. This approach affords promise for scaling the power of synthesized light waveforms to the terawatt and multi-terawatt level and/or to several octaves, by drawing on the LWS-1 and LWS-20 infrastructures, respectively.
The synthesized waveforms will be characterized with broadband femtosecond pulse diagnostics and optical-field-driven second streak cameras operating as an attosecond oscilloscope. Prototypical chirped-mirror based synthesizers will be incorporated in the AS-1/2 beamlines and tested in first applications such as electron wavepacket control in molecules.
contact: E. Goulielmakis
, Y. Deng, L. Veisz
contact: E. Goulielmakis
, Y. Deng, L. Veisz
references:
Attosecond physics, F. Krausz & M.Y. Ivanov Rev. Mod. Phys. 81, 163 (2009)
Attosecond control and measurement: lightwave electronics, E. Goulielmakis et al. Science 317, 769 (2007)
Ultrabroadband coherent light sources based on self-channeling of few-cycle pulses in helium, E. Goulielmakis et al. Opt. Lett. 33, 1407 (2008)
tools:
Fig. 1. Prototypical chirped-mirror-based optical waveform synthesizer under development at LAP. (A) Generic scheme of a multi-channel optical waveform synthesizer based on wide-band chirped dichroic beamsplitters (DBS). (B) Reflectivity curves of DBSs designed and manufactured for a prototypical three-channel synthesizer covering the spectral range of 400-1200 nm, which can now be routinely generated from neon-gas-filled capillaries at LAP. Channel #1: 400-550 nm, Channel #2: 550-800 nm, Channel #3: 800-1200 nm designed to support band-pass reflectance with minimized additional spectral phase. (C) Representative waveforms that can be synthesized with this prototype optical waveform synthesizer, by adjusting amplitude and phase (delay) of the individual channels (6 adjustable “knobs“). (© eg)
Fig. 2. Top-view of the synthesizer illuminated with white-light supercontinuum from one of LAP’s attosecond driver lasers. The scheme can be readily scaled to more independently-addressable channels (as indicated in panel A) and extended towards longer as well as shorter wavelength, where chirped multilayer optics are now becoming available. (© Ivanka Grguras)