Since the mobile Rayleigh Doppler lidar of the University of Science and Technology of China was developed in 2013, more than 100 days of valid nighttime wind data from 15 to 60 km altitude were obtained during recent 3 years. The observation locations cover the northwest (midlatitude) of China: Delingha (37.371°N, 97.374°E), Xinzhou (38.425°N, 112.729°E), and Jiuquan (39.741°N, 98.495°E). Recently, we have extracted perturbations of the wind profiles from the wind field measurements and we have found that inertia gravity waves and mountain waves existed at the same time. The results of wind field and several gravity waves cases are shown in this paper. Typical characteristics of the gravity waves are analyzed in this midlatitude area of China. A 2‐D fast Fourier transform of the wind perturbation shows that a dominant stationary wave mode and a downward wave mode exist simultaneously in the spectrum. A band‐pass 2‐D filter was applied to the spectrum followed by inverse fast Fourier transform to separate inertia gravity waves from stationary mountain waves. The horizontal wavelength is retrieved using hodograph methods, indicating that the inertia waves are generated thousands of kilometers away. Observed mountain waves from a combination of vertical wind and leaned line of sight wind measurements show a small‐angle leaned wave front from the horizontal direction. This kind of gravity wave observation of the stratospheric wind field and its wave patterns is rare and significant for the study of atmospheric dynamics.

Since the first spaceborne Doppler wind lidar, Aeolus, was launched, global wind field observations from space have been possible. Several ground‐ and air‐based validations followed, although most of these comparisons remained below 10 km in the troposphere, with rare validation work for the stratosphere. The Rayleigh Doppler lidar developed by the University of Science and Technology of China (USTC) was deployed in Xinjiang, China, in 2017. It can observe wind speed and temperature in the stratosphere and mesosphere. By setting two geographical ranges centered on the USTC lidar, the Aeolus Rayleigh winds within these ranges can be compared with ground‐based lidar wind data. Furthermore, after eliminating the effect of particulate backscatter on the USTC lidar, the lower limit of the detection range was extended to 10 km to obtain more samples. The mean biases between the Aeolus winds and the USTC lidar winds were 1.05 ± 5.98 (−0.35 ± 4.78) m/s, 1.80 ± 6.30 (−1.88 ± 4.97) m/s, and 0.17 ± 5.45 (0.51 ± 4.44) m/s for all data, ascending orbits, and descending orbits, respectively, in a large (small) geographical range. The geographical distance between the USTC lidar and the Aeolus observation swaths has a significant effect on the wind bias, the farther the distance between Aeolus observation swaths and the USTC lidar, the greater the bias. Whereas, the wind biases have no significant dependency on the time difference of the USTC lidar observation to Aeolus overflight time. Overall, the Aeolus winds are consistent with the USTC lidar winds in the stratosphere.

Dissipative Kerr solitons (DKS)s offer an integrated platform for broad spectrum coverage, which is suitable for the high sensitivity spectroscopy. However, the large linespacing of the soliton comb limits the spectroscopy detection resolution. We overcome this limitation by modulating the soliton comb lines through an external EOM with a tunable RF source. By locking the pump laser to a reference cavity, the linewidth of the pump laser was compressed from $1.13\:\mathrm{MHz}$ to $72\:\mathrm{kHz}$ , leading to the silimar linewidth of comb lines and showing a frequency resolution of hundreds of $kHz$ . Based on the scanned microcomb, we measured the absorption spectra of a gas cell and the high-Q optical modes in the microcavity, with a fast scanning speed of $\mathrm{16\,\,\mathrm{GHz/\mu s}}$ . The scanning comb allows the spectroscopy measurement to cover the whole comb mode spectrum over THz bandwidth. Our setup holds great potential for simple, robust spectroscopy measurement.

Photon-counting dual-comb spectroscopy (DCS) opens new possibilities for deploying DCS in scenarios previously constrained by limited detection sensitivity. However, inevitable optical path fluctuations hinder its practical implementation. Here, we propose a method to ensure the long-term stability of photon-counting DCS, overcoming turbulent optical paths, achieving attowatt-level detection sensitivity and quick acquisition times. Using a compact all-fiber dual-comb system, we achieve 20 nm broadband DCS of H¹³C¹⁴N across the C-band with an average detected power of only 4 attowatts per-comb line. Despite significant vibrations throughout measurements, the spectra maintain comb-line resolution and shot-noise-limited signal-to-noise ratios. Additionally, the system demonstrates successful deployment in open-path measurements, overcoming 93 dB attenuation. Our approach enables remote sensing of CO₂, H₂O, and HDO over a continuous 20-h observation period. This method highlights the potential for applications in fields such as metrology, quantum physics, and atmospheric sensing, especially in turbulent environments like open air or water, within a field-deployable system.

In this work, we present a metastable helium lidar system for the measurements of metastable helium He(2³S) density in the thermosphere and lower exosphere. This lidar system consists of a high power 1,083 nm pulsed laser, a 1 m aperture laser beam expander, six 1 m aperture receiving telescopes and a superconducting nanowire single‐photon detector (SNSPD). This system realizes metastable helium density detection up to 1,000 km. Daily rapid variation of metastable helium density within several hours was measured with a height resolution of 50 km for the first time. It demonstrates the capability of ground‐based lidar for continuous height‐resolved detection of the atmospheric metastable helium in the height range of 200–1,000 km. This is a promising tool to help study the coupling of neutral and ionized atmosphere in this height range and further providing observation basis for space weather prediction.