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    Graphene mode-locked Tm,Ho-codoped crystalline garnet laser producing 70-fs pulses near 21 µm
    (Washington, DC : OSA, 2019) Zhao, Yongguang; Chen, Weidong; Wang, Li; Wang, Yicheng; Pan, Zhongben; Dai, Xiaojun; Yuan, Hualei; Cai, Huaqiang; Zhang, Yan; Bae, Ji Eun; Park, Tae Gwan; Rotermund, Fabian; Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Shen, Deyuan; Griebner, Uwe; Petrov, Valentin
    Bilayer graphene synthesized by chemical vapor deposition is successfully applied as a saturable absorber (SA) for the passive mode-locking of a Tm,Ho:CLNGG laser at 2093nm. Near transform-limited pulses as short as 70 fs, i.e., 10 optical cycles, are produced at a 89 MHz repetition rate with 69 mW average output power. To the best of our knowledge, these are the shortest pulses ever reported from graphene-SA mode-locked Tm, or Ho-lasers in the 2 µm spectral region, including bulk and fiber lasers.
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    Real-time stimulated Raman spectroscopy with a non-collinear optical parametric oscillator
    (Washington, DC : Soc., 2021) Beichert, Luise; Binhammer, Yuliya; Andrade, José R. C.; Mevert, Robin; Kniggendorf, Ann-Kathrin; Roth, Bernhard; Morgner, Uwe
    Ultrafast detection of microplastic particles is becoming a vital problem, as these particles are found in water sources worldwide. Ideally, a live analysis in flow is desirable to directly monitor the water quality for contaminations. Therefore, coherent Raman spectroscopy techniques require fast and broadband tunable lasers to address all relevant spectral regions of the investigated samples. In our work, we combine a high power non-collinear optical parametric oscillator with a real-time stimulated Raman scattering spectroscopy setup. The light source is continously tunable from 700 nm to 1030 nm in less than 10 ms, delivering an average output power of more than 500 mW with sub-ps pulses. We show the immediate observation of mixing processes and the detection of microplastic particles in water solution with a spectral window of more than 2000 cm-1.