Frequency-stabilised laser reference system for water vapour spectroscopy and sensing applications

To acheive the requirements of DIAL instrument, a frequency detection unit (FDU) was realised for water vapour spectroscopy. For this we have developed and realised an ECDL, which can be adjusted at 935 nm or at 942 nm, a region also considered as possible for the WALES (water vapour lidar experiment in space) transmitter. The second main subsystem of the FDU, a frequency reference unit (FRU), grants short- and long-term frequency stabilities of the ISL. Offset-locking with frequency differences up to 19 GHz has been experimentally demonstrated with the proposed technique.