The coherent population trapping (CPT) atomic clock is very promising for use in next-generation spaceborne applications owing to its compactness and high performance. In this paper, we propose and implement a CPT atomic clock based on the direct modulation of a large-modulation-bandwidth and narrow-linewidth distributed Bragg reflector laser, which replaces the usually used external bulk modulator in high-performance CPT clocks. Our method retains the high performance while significantly reducing the clock size. Using this highly compact bichromatic light source and simplest CPT configuration, in which a circularly polarized bichromatic laser interrogates the ⁸⁷Rb atom system, a CPT signal of clock transition with a narrow linewidth and high contrast is observed. We then lock the local oscillator frequency to the CPT resonance and demonstrate an encouraging short-term frequency stability of 3.6 10⁻¹³ τ ^−1/2 (4s ⩽ τ ⩽ 200s). We attribute it to the ultralow laser frequency and intensity noise as well as to the high-quality-factor CPT signal. This study can pave the way for the development of compact high-performance CPT clocks based on our scheme.

相干布居俘获 (CPT) 原子钟由于其紧凑性和高性能而非常有希望用于下一代星载应用。在本文中，我们提出并实现了一种基于大调制带宽和窄线宽分布式布拉格反射激光器的直接调制的 CPT 原子钟，它取代了高性能 CPT 时钟中通常使用的外部体调制器。我们的方法保留了高性能，同时显着减小了时钟大小。使用这种高度紧凑的双色光源和最简单的 CPT 配置，其中圆偏振双色激光询问⁸⁷Rb原子系统，观察到具有窄线宽和高对比度的时钟跃迁的CPT信号。然后，我们将本地振荡器频率锁定到 CPT 谐振，并展示了令人鼓舞的短期频率稳定性 3.6 10 ^-13 τ ^-1/2 (4s ⩽ τ ⩽ 200s)。我们将其归因于超低的激光频率和强度噪声以及高质量因子 CPT 信号。本研究可为基于我们方案的紧凑型高性能 CPT 时钟的开发铺平道路。