[论文解读] Chip-Scale, Sub-Hz Fundamental Sub-kHz Integral Linewidth 780 nm Laser through Self-Injection-Locking a Fabry-Pérot laser to an Ultra-High Q Integrated Resonator

Andrei Isichenko, Nitesh Chauhan+3 more|arXiv (Cornell University)|Jul 11, 2023

Advanced Frequency and Time Standards被引用 9

一句话总结

展示了通过将 Fabry-Pérot 激光器自注入锁定到超高-Q 集成共振腔实现的芯片尺度 780 nm 激光器，具有 sub-Hz 基本线宽和 sub-kHz 积分线宽。

ABSTRACT

Today's state of the art precision experiments in quantum, gravimetry, navigation, time keeping, and fundamental science have strict requirements on the level and spectral distribution of laser frequency noise. For example, the laser interaction with atoms and qubits requires ultra-low frequency noise at multiple offset frequencies due to hyperfine atomic transitions, motional sidebands, and fast pulse sequencing. Chip-scale integration of lasers that meet these requirements is essential for reliability, low-cost, and weight. Here, we demonstrate a significant advancement in atomic precision light sources by realizing a chip-scale, low-cost, 780 nm laser for rubidium atom applications with record-low 640 mHz (white noise floor at 0.2 Hz$^2$/Hz) fundamental and 732 Hz integral linewidths and a frequency noise that is multiple orders of magnitude lower than previous hybrid and heterogeneous self-injection locked 780 nm lasers and lower noise than bulk microresonator implementations. The laser is a Fabry-Pérot laser diode self-injection locked to an ultra-high Q photonic integrated silicon nitride resonator. This performance is enabled by a 145 million resonator Q with a 30 dB extinction ratio, the highest Q at 780 nm, to the best of our knowledge. We analyze the impact of our frequency noise on specific atomic applications including atomic frequency references, Rydberg quantum gates, and cold atom gravimeters. The photonic integrated resonator is fabricated using a CMOS foundry-compatible, wafer-scale process, with demonstrated integration of other components showing promise for a full system-on-a-chip. This performance is scalable to other visible atomic wavelengths, opening the door to a variety of transitions across many atomic species and enabling low-power, compact, ultra-low noise lasers impacting applications including quantum sensing, computing, clocks and more.

研究动机与目标

• 展示适用于铷原子应用的芯片尺度、低成本的 780 nm 激光器。
• 实现创记录的极低基本道和积分线宽，以及超低频噪声。
• 分析频率噪声对原子参考、量子门和冷原子重力计的影响。
• 展示光子集成共振腔的 CMOS 制造兼容性，以便实现潜在的片上系统整合。

提出的方法

• 将 Fabry-Pérot 激光二极管自注入锁定到超高-Q 光子集成硅氮化物共振腔。
• 利用 Q ≈ 145 百万且消光比为 30 dB 的谐振腔。
• 表征激光频率噪声：测量基线和积分线宽。
• 分析频率噪声对原子参考、里德堡门和重力计的影响。
• 利用晶圆级、与 CMOS 兼容的制造工艺实现元件集成。

实验结果

研究问题

• RQ1 当自注入锁定到超高-Q 集成共振腔时，780 nm 激光器能够达到的基线和积分线宽分别是多少？
• RQ2 超高-Q 共振腔如何在相关偏移频率范围内影响激光的频率噪声？
• RQ3 CMOS 制造厂商兼容的光子集成是否能够提供用于原子应用的芯片尺度、极低噪声激光器？
• RQ4 所得噪声性能对原子参考、量子门和冷原子重力计有何影响？

主要发现

• 在 0.2 Hz^2/Hz 处实现 640 mHz 白噪声底。
• 展示 732 Hz 的积分线宽。
• 使用 Q=145 百万且消光比为 30 dB 的共振腔，在 780 nm 处创造了最高 Q 的记录。
• 在噪声性能方面优于此前的混合集/异质自注入锁定的 780 nm 激光器以及某些体微腔实现。
• CMOS 兼容、晶圆级光子集成为潜在的完整片上系统解决方案提供了可能。