The All-Solid-State Narrowband Lidar Developed by Optical Parametric Oscillator/Amplifier (OPO/OPA) Technology for Simultaneous Detection of the Ca and Ca+ Layers

Abstract

We report an all-solid-state narrowband lidar system for the simultaneous detection of Ca and Ca+ layers over Yanqing (40.41°N, 116.01°E). The uniqueness of this lidar lies in its transmitter, which is based on optical parametric oscillation (OPO) and optical parametric amplification (OPA) techniques. The injection seeded OPO and the OPA are pumped by the second harmonic of an injection-seeded Nd:YAG laser, which can generate coherent light at the wavelength of 786 nm or 846 nm lasers, whose second harmonics in turn generate the 393 nm or 423 nm pulses, respectively, for the detection of thermospheric and ionospheric Ca+ and Ca layers. Compared to the conventional dye-based system, this lidar transmitter is a narrowband system (bandwidth < 200 MHz), which has produced a factor of two more output power with higher stability and reliability. The lidar system in Yingqing demonstrated Ca+ detection sensitivity of 0.1 atoms-cm−3 for long-term observation and reached a height of ~300 km. Potential applications and further improvements in this lidar technique are also discussed in this paper.

Seasonal Variation in the Mesospheric Ca Layer and Ca+ Layer Simultaneously Observed over Beijing (40.41°N, 116.01°E)

“…From March 2020 to December 2021, there was a consistent monitoring of the Ca + layer within the E-F region. These special structures have not been observed before [2,20].…”

“…This laser beam serves as a pump light source, supplying the necessary energy for the oscillation and amplification processes of the 786 nm and 846 nm lasers. The SHG module facilitates the generation of the 393 nm and 423 nm lasers from the 786 nm and 846 nm lasers, respectively [20].…”

“…The OPO lidar utilizes an all-solid-state technology, with the laser component providing control over the output spot. In contrast, dye lasers necessitate regular human interaction during the observation process and exhibit suboptimal uniformity in the output spot, which manifests as a crescent-shaped light spot [20]. The OPO lidar system exhibits notable stability and reliability, enabling sustained and consistent operation over extended durations.…”

Automation in Middle- and Upper-Atmosphere LIDAR Operations: A Maximum Rayleigh Altitude Prediction System Based on Night Sky Imagery

“…Existing weather forecasting techniques, whether derived from surface-based meteorological observation stations or satellite cloud maps, fall short in terms of location accuracy and timeliness [8]. MUA-LIDAR operations are highly weather-dependent, with optimal observations attainable only in clear weather [9]. In adverse weather conditions (e.g., cloud cover, fog, or haze), MUA-LIDAR can only capture echo signals below 35 km, which is insignificant for the inversion of crucial MUA parameters like temperature, density, and wind fields.…”