光束指向稳定系统基于对光束位置和角度的控制，能够实现对光束指向的高精度主动控制，在微纳光刻及超分辨成像等领域中发挥着重要的作用。为了实现光束的长时间指向稳定，提出一种分离式调控的小型化光束指向稳定系统，消除了传统方案中双反射镜校正带来的耦合误差，大幅度提升了光束指向精度的控制性能。对比测试结果表明，基于该方法的光束指向稳定系统对光束位置的稳定精度（RMS值）可达0.3 μm，角度稳定精度（RMS值）达到1 μrad；施加一定幅度的主动扰动后的测试结果表明，该系统在较大的光源抖动下仍能保持同一量级的稳定精度。相比于同样测试条件下的两种商业化光束指向稳定系统，其位置抖动与角度抖动性能可提高50%以上。

Controlling the delivery of multi-terawatt and petawatt laser pulses to final focus, both in position and angle, is critical to many laser applications such as optical guiding, laser–plasma acceleration, and laser-produced secondary radiation. We present an online, non-destructive laser diagnostic, capable of measuring the transverse position and pointing angle at focus. The diagnostic is based on a unique double-surface-coated wedged-mirror design for the final steering optic in the laser line, producing a witness beam highly correlated with the main beam. By propagating low-power kilohertz pulses to focus, we observed spectra of focus position and pointing angle fluctuations dominated by frequencies below 70 Hz. The setup was also used to characterize the excellent position and pointing angle correlation of the 1 Hz high-power laser pulses to this low-power kilohertz pulse train, opening a promising path to fast non-perturbative feedback concepts even on few-hertz-class high-power laser systems.

We demonstrate two ultra-stable laser systems at 1064 nm by independently stabilizing two 10-cm-long Fabry–Pérot cavities. The reference cavities are on a cubic spacer, which is rigidly mounted for both low sensitivity to environmental vibration and ability for transportation. By comparing against an independent ultra-stable laser at 578 nm via an optical frequency comb, the 1064 nm lasers are measured to have frequency instabilities of 6 × 10^?16 at 1 s averaging time.

Using a heavily erbium-doped aluminosilicate fiber prepared by the sol-gel method combined with high temperature sintering, the temperature dependence of the spectrum around the 1.55 nm band and single-mode fiber laser properties were investigated, respectively. The absorption cross section increases 29.2% at ～1558 nm with the temperature increasing from 20°C to 140°C, while the emission cross section slightly increases 4.3%. In addition, the laser slope of the heavily erbium-doped aluminosilicate fiber at 1558 nm decreases 4.4% from 10.8% to 6.4% with the temperature increasing from 18°C to 440°C. Meanwhile, an experiment lasting 3 h proves that the fiber laser has excellent stability below 440°C.

Excess frequency noise induced by mechanical vibration is the dominant noise source at low Fourier frequencies in fiber-delay-line stabilized lasers. To resolve this problem, a double-winding fiber spool is designed and implemented that has ultralow acceleration sensitivity in all spatial directions. By carefully choosing the optimal geometry parameters of the fiber spool, we achieve acceleration sensitivity of 8 × 10 ¹¹/g and 3 × 10 ¹¹/g (g denotes the gravitational acceleration) in axial and radial directions, respectively.

We demonstrate the frequency stabilization of a 1.55 μm erbium-doped fiber laser by locking it to a 5-km-long optical fiber delay line (FDL). The stabilized laser is characterized via comparison with a second identical laser system. We obtain a fractional frequency stability of better than 3 × 10 ¹⁵ over time scales of 1–10 s and a laser linewidth of 0.2 Hz, which is the narrowest linewidth of an FDL-stabilized laser observed to date.

A clock laser based on a 30-cm-long ultrahigh finesse optical cavity was developed to improve the frequency stability of the Sr optical lattice clock at the National Institute of Metrology. Using this clock laser to probe the spin-polarized Sr87 atoms, a Rabi transition linewidth of 1.8 Hz was obtained with 500 ms interrogation time. Two independent digital servos are used to alternatively lock the clock laser to the S01 (mF=+9/2)→P03 (mF=+9/2) transition. The Allan deviation shows that the short-term frequency stability is better than 3.2×10 16 and averages down followed by 1.8×10 15/τ.