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research activities on high-repetition-rate femtosecond sources

— Kafai Mak —

Novel high-power femtosecond oscillators for mid-infrared radiation generation

Coherent laser radiation forms the backbone
of modern optical research.
In HFS, we continue
to push the frontiers of laser development,
aiming to generate highly-intense optical few- cycle pulses
at exotic wavelengths.
We aim to generate these pulses not at thousands,
but millions of times per second.
This higher repetition frequency
vastly enhances the available photon-flux,
which is crucial for many types of experiments.

While visible and near-infrared
lasers are becoming ubiquitous in modern research,
the same cannot be said for coherent sources in important spectral regions such as in the mid-infrared (2-20 µm).
The mid-IR region is uniquely positioned
to spectroscopically identify complex molecules
based on their unique vibrational signatures.
Consequently, we are developing novel mid-IR laser light sources that can be utilized by researchers,
including our colleagues at FRM and BIRD,
to detect in biological samples early hints of illnesses at unprecedented sensitivity and dynamic range.

To this end, a variety of technologies are being developed
in our group. From high-power thin-disk oscillators
that can deliver hundreds of Watts of average power, to pulse compression and frequency conversion techniques
that transform the raw power into ultrashort mid-IR pulses.
Also being pursued is the generation of
femtosecond light pulses
directly within the mid-IR range using state-of-the-art laser materials, and doing so at unprecedented efficiencies thanks to our innovative use of direct diode-pumping.

Graphical Abstract

learn more about high-repetition-rate femtosecond sources

— Kafai Mak —

Tools, Techniques & Labs

1) Diode-pumping of Cr:ZnS femtosecond oscillators and amplifiers to improve noise performance and increase accessibility.

2) Generating hundreds of Watts of average power from a thin-disk laser resonator to enable high-photon-flux experiments.

3) Nonlinear spectral broadening and pulse compression to reach hard-to-access spectral regions and generate laser pulses approaching a single optical-cycle.

4) Stabilization of carrier-envelope offset in pulse trains for emerging frequency-comb applications.

  • Adjusting all solid state spectral broadening and compression stage
    Adjusting all solid state spectral broadening and compression stage
  • White light generation. Parabolic mirror is necessary to coolimate the white light.
    White light generation. Parabolic mirror is necessary to coolimate the white light.
  • All solid state spectral broadening. Herriott cell
    All solid state spectral broadening. Herriott cell
  • A part of a dispersive mirror compressor. The mirrors are manufactured by Dr. Vladimir Pervak.
    A part of a dispersive mirror compressor. The mirrors are manufactured by Dr. Vladimir Pervak.
  • Inside of a thin-disk oscillator cavity
    Inside of a thin-disk oscillator cavity
  • Nonlinear dielectric coating (NDC) inside of an oscillator
    Nonlinear dielectric coating (NDC) inside of an oscillator
  • Jinwei Zhang with the first Ho:YAG thin-disk oscillator
    Jinwei Zhang with the first Ho:YAG thin-disk oscillator