High-Power Unique-Stability Laser Source For Quantum Applications

UCL将描述Yb光纤放大器中Mephisto激光系统放大的噪声特性。我们在伦敦大学学院的团队经常使用低噪声激光系统(包括Mephisto)，为捕获和冷却原子、分子和纳米粒子提供稳定的高激光光源。由于我们的实验对激光噪声特别敏感，它们为这个激光系统提供了一个理想的试验台。为了测试该系统，其中一个激光器输出将被锁定到一个窄的外腔谐振，而另一个将以明确定义的GHz频移从该频率失谐。我们将进行测试，以验证锁定激光器的频率将能够快速跟踪高精细度腔中的热、机械和声频漂移。将测试激光器的第二个输出，以了解它将在多大程度上遵循与腔锁定输出相同的频率调制。为了表征该系统的性能，我们将测量相位和幅度噪声及其对捕获和光学机械实验的可能影响。这种类型的实验对激光噪声特别敏感，因为振荡器的质量很大(10^-17公斤)，与我们的原子俘获实验相比。目前，该系统通过空腔冷却方法冷却到开尔文质量中心的毫微温度。在这里，Mephisto将被直接锁定到腔的高阶TEM模，而第二个光纤放大组件将被用于提供距离主激光输出1.3 GHz频率偏移的高功率冷却光束。这束光束将与相邻的TEM00共振发生红移，最高可达100千赫。所有输出的频率稳定度必须优于1 kHz。理想情况下，放大器中的噪声必须保持在与Mephisto相同的水平。所有数据将以连贯的方式共享，并将在计划的实验之前进行定期讨论，以确保系统达到目标，以满足这些类型的实验的要求。

UCL will characterise the noise characteristics of the amplification of the Mephisto laser system in Yb fibre amplifiers. Our group at UCL regularly use low noise laser systems (including the Mephisto) to provide a stable high laser source for trapping and cooling of atoms, molecules and nanoparticles. As our experiments are particularly sensitive to laser noise they offer an ideal testbed for this laser system. To test the system, one of the lasers outputs will be locked to a narrow external cavity resonance while the other is detuned from this frequency at a well- defined GHz frequency shift. We will test to verify that the frequency of the locking laser will be able to rapidly follow thermal, mechanical and acoustic frequency drifts in the high finesse cavity. The second output of the laser will be tested to understand how well it will follow the same frequency modulations as the cavity locking output. To characterise the capabilities of this system we will measure the phase and amplitude noise and its probable effects on trapping and optomechanics experiments. This type of experiment is particularly sensitive to laser noise due to the large mass of the oscillator (10^-17 kg) when compared to our atomic argon trapping experiments. Currently this system is cooled down to milliKelvin centre-of-mass temperatures by cavity cooling methods. Here the Mephisto will be directly locked to a higher order TEM mode of the cavity while the second fibre amplified component will be used to provide the high power cooling beam that is frequency offset by 1.3 GHz from the main laser output. This beam will be red-detuned from the adjacent TEM00 resonance by up to 100 kHz. The frequency stability of all outputs must be better than 1 kHz. The noise in the amplifier must be ideally maintained at the same level of the Mephisto. All data will be shared with Coherent, and regular discussions will be held before the planned experiments to make sure the system is on target to meet the requirements for these types of experiments.