Energy scaling, second Stokes oscillation and Raman gain-guiding in monolithic diamond Raman lasers

Savitski, Vasili G. and Demetriou, Giorgos and Reilly, Sean and Liu, Hangyu and Gu, Erdan and Dawson, Martin D. and Kemp, Alan (2018) Energy scaling, second Stokes oscillation and Raman gain-guiding in monolithic diamond Raman lasers. IEEE Journal of Quantum Electronics, 54 (6). 1700408. ISSN 0018-9197 (https://doi.org/10.1109/JQE.2018.2875561)

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Abstract

Energy scaling of the 1st Stokes oscillation is compared in micro-lensed and plane-plane monolithic diamond Raman lasers under 532 nm pumping. A maximum Raman pulse energy of 92 µJ at 573 nm was achieved with the micro-lensed device, while in a plane-plane configuration the maximum Raman pulse energy was 3.1 mJ. 2nd Stokes generation at 620 nm in 2 and 1 mm long micro-lensed monolithic diamond Raman lasers is also reported. The best conversion efficiency from the pump at 532 nm, namely 63 %, was observed in a 2 mm long crystal at the pump pulse intensity of 4.5 GW/cm2. By measuring the output Raman laser beam caustic it was found that the 2nd Stokes intracavity beam radius at the output coupler of the micro-lensed device is at least two times smaller than that expected from the ABCD matrix calculations of the resonator mode. A Raman gain-guiding mechanism is suggested to explain this difference.