Demonstration of the 1.53-µm coherent DIAL for simultaneous profiling of water vapor density and wind speed

Three-dimensional detection of CO2 and wind using a 1.57 µm coherent differential absorption lidar

A 1.57-µm coherent differential absorption lidar is demonstrated for measuring three-dimensional CO2 and wind fields simultaneously. The maximum detection range of CO2 is up to 6 km with a range resolution of 120 m and a time resolution of 1 min. A preliminary assessment of instrument performance is made with a 1-week continuous observation. The CO2 concentration over a column from 1920 to 2040 m is compared with the one measured by an optical cavity ring-down spectrometer placed on a 2 km-away meteorological tower. The concentration is strongly correlated with the in-situ spectrometer with a correlation coefficient and RMSE of 0.91 and 5.24 ppm. The measurement accuracy of CO2 is specified with a mean and standard deviation of 2.05 ppm and 7.18 ppm, respectively. The regional CO2 concentration and the three-dimensional wind fields are obtained through different scanning modes. Further analysis is conducted on vertical mixing and horizontal transport of CO2 by combining with the measured wind fields.

Evaluation of a coherent 2-µm differential absorption lidar for water vapor and radial wind velocity measurements

The performance of a coherent 2-µm differential absorption lidar (DIAL) for simultaneously measuring water vapor (H₂O) and radial wind velocity was evaluated. For measuring H₂O, a wavelength locking technique was applied to the H₂O-DIAL system. The H₂O-DIAL system was evaluated under summer daytime conditions in Tokyo, Japan. H₂O-DIAL measurements were compared with measurements from radiosondes. The H₂O-DIAL-derived volumetric humidity values agreed with the radiosonde-derived values over the range from 11 to 20 g/m³ with a correlation coefficient of 0.81 and a root-mean-square difference of 1.46 g/m³. Comparisons between the H₂O-DIAL and the in-situ surface meteorological sensors demonstrated the simultaneous measurement of H₂O and radial wind velocity.

Single-frequency 45-mJ pulses from a MOPA system using an Er,Yb:glass planar waveguide amplifier and a large mode area Er-doped fiber amplifier

We demonstrate a master oscillator power amplifier (MOPA) system that emits single-frequency high-energy optical pulses at 1540 nm using an Er,Yb:glass planar waveguide amplifier and a large mode area Er-doped fiber amplifier. A double under-cladding and a 50-µm-thick core structure are employed for the planar waveguide amplifier to increase the output energy without degrading the beam quality. A pulse energy of 45.2 mJ with a peak power of 27 kW is generated at a pulse repetition rate of 150 Hz with a pulse duration of 1.7 µs. Moreover, the beam quality factor M² of the output beam is 1.84 at the highest pulse energy thanks to its waveguide structure.