u.MIR: Ultrastable and Ultrafast Mid-Infrared Laser Sources
We are u.MIR:
We build ultrafast Cr:ZnS/Se lasers, we stabilize them to ultrastable frequency combs, and we use nonlinear optics to convert their radiation to mid-infrared range.
We are open to collaborations: if you think that our unique laser sources can be valuable for your research application, do not hestitate to contact us!
Cr:ZnS/Se laser technology
In our laboratories we develop mode-locked laser oscillators based on chromium-doped chalcogenide crystals, such as Cr:ZnS or Cr:ZnSe. They can emit ultrashort (<30 fs) laser pulses at 2.3 µm, and thus they are termed as „Ti:sapphire of the mid-infrared”. We use nonlinear optics and chirped mirrors to spectrally broaden and compress the pulses to sub-10-fs single-cycle duration.
We believe that Cr:ZnS/Se lasers can be a true successor of the Ti:sapphire technology, as it opens new possibilities in ultrafast science in the mid-infrared spectral range.
Ultra-low noise Cr:ZnS/Se lasers
The power stability of a laser is a crucial parameter for many demanding applications. It turns out that the degree of power fluctuations is governed by the stability of the employed pump source. We have used our expertise in development of low-noise electronics and fiber lasers to design an ultra-stable erbium-doped fiber amplifiers for pumping Cr:ZnS/Se lasers. This allows us to reach an unprecedentedly low-noise operation with relative intensity noise (RIN) below 0.005%.
Frequency combs and CEP-stabilization
Ultrashort laser pulses are the shortest events the mankind has ever created and they provide a technological basis for exploring the fundamental laws of nature with attosecond temporal resolution far exceeding the atomic unit of time and with stability equivalent to a single second per the age of the universe. This is allowed by a frequency comb, which is a mode-locked laser with actively stabilized repetition rate and carrier-envelope phase (CEP). We stabilize our Cr:ZnS/Se lasers to frequency combs by using novel techniques for CEP stabilization that we developed. Our low-noise Cr:ZnS/Se oscillators are the most phase stable few-cycle lasers ever demonstrated with <6 mrad residual noise.
Experimental scheme of our Cr:ZnS optical frequency comb
Nonlinear optics for spectral conversion
Direct generation of ultrashort light pulses in the mid-infrared (2 – 20 µm) or long-infrared (> 20 µm) is impossible due to the lack of available light sources. Cr:ZnS/ZnSe lasers are perfect driving sources for indirect generation of long wavelength radiation via spectral conversion relying on nonlinear optics. Towards this goal, we exploit various nonlinear phenomena. Intrapulse difference frequency generation (IP-DFG) in nonlinear crystals allows to generate almost 4-octave spanning supercontinnum spanning to 12 µm. Raman soliton self-frequency shift in fluoride fibers helps us to tune the soliton wavelength down to to 4 µm.