We report on the spectroscopic characterization, absorption saturation, and excited-state dynamics of GR1 centers in synthetic diamonds. The non-linear optical measurements reveal an efficient bleaching of the GR1 center’s ground level under ns-pulsed 633 nm excitation. The maxima of absorption and emission cross sections were estimated to be 4.5 × 10⁻¹⁷ cm² and 9 × 10⁻¹⁷ cm² at 630 nm and 780 nm, respectively. The radiative lifetime of the excited level was estimated to be 8.5 ns. The 658 nm probe kinetics uncovered relaxation of ¹T₂ excited level going predominantly to a metastable state with a lifetime of 220 μs. An induced absorption detected with the use of a highly concentrated diamond sample could be due to up-conversion and photoionization processes in additional impurity-vacancy center with absorption at the short-wavelength tail of GR1. The results presented here indicate that synthetic diamonds with GR1 centers could serve as near infrared gain media or passive Q-switchers for laser cavities over the 633–750 nm spectral range. Optimization of the center concentration and the crystal parameters are required to minimize the induced absorption at the lasing wavelengths.

中文翻译：

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合成钻石中GR1中心的光谱

我们报告了合成钻石中GR1中心的光谱表征，吸收饱和和激发态动力学。非线性光学测量揭示了在ns脉冲633 nm激发下GR1中心地平面的有效漂白。在630nm和780nm处，吸收和发射截面的最大值估计分别为4.5×10 ^-17 cm ²和9×10 ^-17 cm ²。激发能级的辐射寿命估计为8.5 ns。658 nm探针动力学揭示了¹ T _2的弛豫激发能级主要变为亚稳态，寿命为220μs。使用高浓度金刚石样品检测到的诱导吸收可能是由于在其他杂质空位中心的上转换和光电离过程，而在GR1的短波长尾部有吸收。此处显示的结果表明，具有GR1中心的合成钻石可以用作近红外增益介质或无源Q切换器，用于633-750 nm光谱范围内的激光腔。需要使中心浓度和晶体参数最优化，以最小化在激光波长处的感应吸收。