Spectroscopic investigations of Tm3+ doped CdF2 single crystals and infrared laser potentialities

By use of standard Bridgman technique, CdF2 single crystals doped with Tm3+ have been obtained with good optical quality. XRD analysis has been performed confirming the cubic structure. An ordered sequence of spectroscopic measurements (including absorption, excitation, emission and fluorescence dynamics) was carried out at room temperature. By exploiting both UV–Visible and near-infrared absorption spectra, the JO phenomenological parameters are determined by taking into account the complete refractive index dispersion, which allowed us to compute the probabilities of all transitions. Under 355 nm wavelength excitation, the Stokes emission spectrum exhibits mainly an intense blue emission line around 450 nm which is associated to 1D2→3F4 excited state transition. Whereas, the anti-Stokes blue emission around 480 nm associated to 1G4→3H6 transition is obtained under infrared excitation according to a two photon absorption mechanism. For both blue emissions, the CIE chromaticity coordinates of CdF2:Tm3+ are located in the blue region. As trivalent Tm3+ ions are known for their emissions in the near- and mid-infrared spectral ranges suitable for efficient laser operation, we have systematically studied the fluorescence behavior of the eye safe emission (pointed at ∼1.8 μm) and associated to the 3F4 → 3H6 transition. Such transition exhibit a relatively high emission cross-section (σem = 0.22 × 10−20 cm2) and a positive gain cross-section at low pumping threshold with a metastable fluorescence lifetime decay. •Thulium doped CdF2 single crystals with good optical quality grown by Bridgman technique.•Spectroscopic properties investigated by use of the Judd–Ofelt theory.•Excitation, Stokes and upconversion emission spectra, fluorescence decays recorded at room temperature.•Blue emission generated by upconversion and Laser potentialities of blue emission at 480 nm.•Laser potentialities of eye-safe near infrared emission around 1.8 μm under a laser diode excitation.