Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers

Identifier:  imarina:3996507

Handle: https://hdl.handle.net/20.500.11797/imarina3996507

Authors:  Pan, ZB; Serres, JM; Kifle, E; Loiko, P; Yuan, HL; Dai, XJ; Cai, HQ; Aguilo, M; Díaz, F; Wang, YC; Zhao, YG; Griebner, U; Petrov, V; Mateos, X

Abstract:
© 2018 Optical Society of America. Tm3+, X+-codoped disordered calcium niobium garnet crystals, Ca3Nb2-xGa3+xO12(CNGG), where X+is an alkali cation, Na+or Li+(shortly Tm:CNNGG and Tm:CLNGG, respectively), are grown by the Czochralski method. A comparative study of their spectroscopic and laser properties is performed. Raman spectra are also studied. For Tm:CNNGG, the Judd-Ofelt parameters for the Tm3+dopant ion are Ω2= 1.847, Ω4= 1.558 and Ω6= 0.862 [10-20cm2] and the radiative lifetime of the3F4state is 4.11 ms. The absorption, stimulated-emission (σSE) and gain cross-sections are determined for the3H6↔3F4Tm3+-ion transition. For Tm:CNNGG, the maximum σSEis 0.49 × 10-20cm2at 1867 nm. Both crystals exhibit flat and broad gain spectra extending beyond 2 μm. A compact diodepumped Tm:CNNGG laser has generated 1.05 W at 2007.7 nm with a slope efficiency of 35%. Broadband tuning of Tm:CNNGG and Tm:CLNGG lasers (tuning ranges of 168 nm and 224 nm, respectively), was demonstrated. The Tm3+, X+-codoped CNGG crystals are the promising for sub-100 fs pulse generation at ~2 μm.