A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operati...A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operation was achieved due to the spatial-hole-burning free nature of Raman gain and was maintained at the highest available pump power by suppressing the parasitic stimulated Brillouin scattering(SBS).A folded-cavity design was employed for reducing the perturbing effect of resonances at the pump frequency.At a pump power of 69 W,the maximum Stokes output reached 20.6 W,corresponding to a 30%optical-to-optical conversion efficiency from 1064to 1240 nm.The result shows that parasitic SBS is the main physical process disturbing the SLM operation of Raman oscillator at higher power.In addition,for the first time,the spectral linewidth of a CW SLM diamond Raman laser was resolved using the long-delayed self-heterodyne interferometric method,which is 105 kHz at 20 W.展开更多
Results on stress analysis for single-crystal diamonds are presented. Isolated crystals were studied by Raman mapping and depth profiling techniques, using confocal microscopy. Diamonds were deposited on molybdenum an...Results on stress analysis for single-crystal diamonds are presented. Isolated crystals were studied by Raman mapping and depth profiling techniques, using confocal microscopy. Diamonds were deposited on molybdenum and tantalum by hot filament and microwave CVD methods at growth rates between 10 and 30 μm·h-1. Crystals from 10 to 40 μm size were examined. Local stress was evaluated by analyzing the position, broadening and splitting of the 1332 cm-1 Raman peak in a 3D mapping. For the (001) orientation, the most stressed zone was found at the center of the crystal base, close to the interface with the substrate: a Raman peak around 1340 cm-1 was measured, corresponding to a pressure c.a. 3 GPa, according to our dynamical calculations. This peak disappears few microns out of the center, suggesting that this highly concentrated stress sector was the nucleation zone of the crystal. A shifting and slight broadening of the 1332 cm-1 band was observed in the rest of the crystal. The causes of these effects are discussed: they proved not to be due to anisotropic stress but to refractive effects. Same results were found for different crystal sizes and growth rates.展开更多
基金supported by the National Natural Science Foundation of China(No.62005073)the Program of the State Key Laboratory of Crystal Materials(No.KF2101)+3 种基金the National Key Research and Development Program of China(No.2020YFC2200300)the Program of the State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202207)the Research Funds of Hangzhou Institute for Advanced Study(No.2022ZZ01006)the Hangzhou Agricultural and Social Development initiative Design Project(No.2022ZDSJ0846).
文摘A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operation was achieved due to the spatial-hole-burning free nature of Raman gain and was maintained at the highest available pump power by suppressing the parasitic stimulated Brillouin scattering(SBS).A folded-cavity design was employed for reducing the perturbing effect of resonances at the pump frequency.At a pump power of 69 W,the maximum Stokes output reached 20.6 W,corresponding to a 30%optical-to-optical conversion efficiency from 1064to 1240 nm.The result shows that parasitic SBS is the main physical process disturbing the SLM operation of Raman oscillator at higher power.In addition,for the first time,the spectral linewidth of a CW SLM diamond Raman laser was resolved using the long-delayed self-heterodyne interferometric method,which is 105 kHz at 20 W.
文摘Results on stress analysis for single-crystal diamonds are presented. Isolated crystals were studied by Raman mapping and depth profiling techniques, using confocal microscopy. Diamonds were deposited on molybdenum and tantalum by hot filament and microwave CVD methods at growth rates between 10 and 30 μm·h-1. Crystals from 10 to 40 μm size were examined. Local stress was evaluated by analyzing the position, broadening and splitting of the 1332 cm-1 Raman peak in a 3D mapping. For the (001) orientation, the most stressed zone was found at the center of the crystal base, close to the interface with the substrate: a Raman peak around 1340 cm-1 was measured, corresponding to a pressure c.a. 3 GPa, according to our dynamical calculations. This peak disappears few microns out of the center, suggesting that this highly concentrated stress sector was the nucleation zone of the crystal. A shifting and slight broadening of the 1332 cm-1 band was observed in the rest of the crystal. The causes of these effects are discussed: they proved not to be due to anisotropic stress but to refractive effects. Same results were found for different crystal sizes and growth rates.
