Beica H C, Pouliot A, Carew A, Vorozcovs A, Afkhami-Jeddi N, Vacheresse T, Carlse G, Dowling P, Barron B, Kumarakrishnan A
Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.
Rev Sci Instrum. 2019 Aug;90(8):085113. doi: 10.1063/1.5112760.
We demonstrate the performance characteristics of a new class of vacuum-sealed, autolocking diode laser systems and their applications to precision metrology. The laser is based on adaptations of a design that uses optical feedback from an interference filter and it includes a vacuum-sealed cavity, an interchangeable base-plate, and an autolocking digital controller. A change of the base-plate allows operation at desired wavelengths in the visible and near infrared spectral range, whereas the autolocking ability allows the laser to be tuned and frequency stabilized with respect to atomic, molecular, and solid-state resonances without human intervention using a variety of control algorithms programmed into the same controller. We characterize the frequency stability of this laser system based on the Allan deviation (ADEV) of the beat note and of the lock signal. We find that the ADEV floor of 2 × 10 and short-term linewidth of ∼200 kHz are strongly influenced by current noise and vacuum sealing. Reducing the current noise and cavity pressure decreases the ADEV floor and increases the averaging time at which the floor occurs, which is a signature of long-term stability. We also show that evacuating the cavity to ∼1 Torr reduces the range of the correction signal of the feedback loop by approximately one order of magnitude, thereby increasing the lock range of the controller. The long-term stability allows the laser to be incorporated into a commercial gravimeter for accurate measurements of gravitational acceleration at the level of a few parts-per-billion, which are comparable to values obtained with an iodine-stabilized He-Ne laser. The autolocking and pattern-matching features of the controller allow the laser to be tuned and stabilized with respect to a temperature tunable transmission spectrum of a fiber-Bragg grating. This capability may be suitable for the development of a differential absorption LIDAR transmitter that can generate data at both on-line and off-line lock points using a single laser.
我们展示了一类新型真空密封、自动锁定二极管激光系统的性能特征及其在精密计量中的应用。该激光器基于一种采用干涉滤光片光学反馈的设计改进，它包括一个真空密封腔、一个可互换的基板和一个自动锁定数字控制器。更换基板可使激光器在可见和近红外光谱范围内的所需波长下运行，而自动锁定功能使激光器能够利用编程到同一控制器中的各种控制算法，在无需人工干预的情况下，相对于原子、分子和固态共振进行调谐和频率稳定。我们基于拍频和锁定信号的阿伦偏差（ADEV）对该激光系统的频率稳定性进行了表征。我们发现，2×10的ADEV本底和约200 kHz的短期线宽受到电流噪声和真空密封的强烈影响。降低电流噪声和腔压力会降低ADEV本底，并增加本底出现时的平均时间，这是长期稳定性的一个标志。我们还表明，将腔抽空至约1托可使反馈回路的校正信号范围降低约一个数量级，从而增加控制器的锁定范围。长期稳定性使该激光器能够集成到商业重力仪中，用于精确测量十亿分之几水平的重力加速度，这与碘稳定的氦氖激光器获得的值相当。控制器的自动锁定和模式匹配功能使激光器能够相对于光纤布拉格光栅的温度可调透射光谱进行调谐和稳定。这种能力可能适用于开发一种差分吸收激光雷达发射器，该发射器可以使用单个激光器在在线和离线锁定点生成数据。
