Abstract
The demand for and usage of broadband coherent mid-infrared sources, such as those provided by synchrotron facilities, are growing. Since most organic molecules exhibit characteristic vibrational modes in the wavelength range between 500 and 4000 cm−1, such broadband coherent sources enable micro- or even nano-spectroscopic applications at or below the diffraction limit with a high signal-to-noise ratio1, 2, 3. These techniques have been applied in diverse fields ranging from life sciences, material analysis, and time-resolved spectroscopy. Here we demonstrate a broadband, coherent and intrinsically carrier-envelope-phase-stable source with a spectrum spanning from 500 to 2250 cm−1 (−30 dB) at an average power of 24 mW and a repetition rate of 77 MHz. This performance is enabled by the first mode-locked thin-disk oscillator operating at 2 μm wavelength, providing a tenfold increase in average power over femtosecond oscillators previously demonstrated in this wavelength range4. Multi-octave spectral coverage from this compact and power-scalable system opens up a range of time- and frequency-domain spectroscopic applications.
Highlights
The demand for and usage of broadband coherent mid-infrared sources, such as those provided by synchrotron facilities, are growing
Since most organic molecules exhibit characteristic vibrational modes in the wavelength range between 500 and 4000 cm − 1, such broadband coherent sources enable micro- or even nano-spectroscopic applications at or below the diffraction limit with a high signal-to-noise ratio[1,2,3]. These techniques have been applied in diverse fields ranging from life sciences, material analysis, and time-resolved spectroscopy
We demonstrate a broadband, coherent and intrinsically carrier-envelope-phase-stable source with a spectrum spanning from 500 to 2250 cm − 1 (−30 dB) at an average power of 24 mW and a repetition rate of 77 MHz. This performance is enabled by the first mode-locked thin-disk oscillator operating at 2 μm wavelength, providing a tenfold increase in average power over femtosecond oscillators previously demonstrated in this wavelength range[4]
Summary
It is transparent in a broad wavelength range from 0.65 to 20 μm and even up to 30 μm for shorter crystals[29] It has a high optical damage threshold[22], high thermal conductivity and minimal two-photon absorption at a pump wavelength of ~ 0.6 eV and is readily available commercially. For these reasons, it has been frequently used for MIR and THz generation and detection via EOS10,29. It should be noted that the spectrum at longer wavelengths (starting from 11 μm) was strongly affected by the low transmission of doi:10.1038/lsa.2017.180
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