Gredat Grégory, Chatterjee Debanuj, Baili Ghaya, Gutty François, Sagnes Isabelle, Goldfarb Fabienne, Bretenaker Fabien, Liu Hui
Opt Express. 2018 Oct 1;26(20):26217-26226. doi: 10.1364/OE.26.026217.
We report a fully-correlated multi-mode pumping architecture optimized for dramatic noise reduction of a class-A dual-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). Thanks to amplitude division of a laser diode, the two orthogonally polarized modes emitted by the VECSEL oscillating at 852 nm are separately pumped by two beams exhibiting fully in-phase correlated intensity noises. This is shown to lead to very strong and in-phase correlations between the two lasing modes intensities. As a result, the phase noise power spectral density of the RF beat note generated by the two modes undergoes a drastic reduction of about 10 to 20 dB throughout the whole frequency range from 10 kHz to 20 MHz and falls below the detection floor above a few MHz. A good agreement is found with a model which uses the framework of rate equations coupled by cross-saturation. The remaining phase noise is attributed to thermal effects and additional technical noises and lies mainly within the bandwidth of a phase-locked-loop.
我们报道了一种针对A类双频垂直外腔面发射激光器（VECSEL）显著降低噪声而优化的全相关多模泵浦架构。得益于激光二极管的振幅分割，VECSEL发射的在852 nm振荡的两个正交偏振模式由两束具有完全同相相关强度噪声的光束分别泵浦。结果表明，这导致了两个激光模式强度之间非常强的同相相关性。因此，由这两个模式产生的射频拍频的相位噪声功率谱密度在从10 kHz到20 MHz的整个频率范围内大幅降低约10至20 dB，并在几兆赫兹以上降至检测下限以下。与使用交叉饱和耦合速率方程框架的模型取得了很好的一致性。剩余的相位噪声归因于热效应和额外的技术噪声，并且主要位于锁相环的带宽内。
