Remote Water Temperature Measurements Based on Brillouin Scattering with a Frequency Doubled Pulsed Yb:doped Fiber Amplifier

Abstract

Temperature profiles of the ocean are of interest for weather forecasts, climate studies and oceanography in general. Currently, mostly in situ techniques such as fixed buoys or bathythermographs deliver oceanic temperature profiles. A LIDAR method based on Brillouin scattering is an attractive alternative for remote sensing of such water temperature profiles. It makes it possible to deliver cost-effective on-line data covering an extended region of the ocean. The temperature measurement is based on spontaneous Brillouin scattering in water. In this contribution, we present the first water temperature measurements using a Yb:doped pulsed fiber amplifier. The fiber amplifier is a custom designed device which can be operated in a vibrational environment while emitting narrow bandwidth laser pulses. The device shows promising performance and demonstrates the feasibility of this approach. Furthermore, the current status of the receiver is briefly discussed; it is based on an excited state Faraday anomalous dispersion optical filter.

Review of profiling oceanographic lidar

“…136 It has not found widespread application because the required laser stability and receiver frequency accuracy have been difficult to obtain outside of the laboratory. These are both areas of active research, [136][137][138][139] and the application of lidar profiling of temperature in the open ocean can be expected in the future. 136 …”

Brillouin lidar and related basic physics

“…Substituting (l − z) by t p υ p 2 in Eq. (3)(4)(5)(6)(7)(8)(9)(10), and neglecting dispersion effect, we have…”

“…In the past three decades, the lidar system based on Brillouin scattering for remote sensing of the ocean has attracted attention [1][2][3][4][5][6][7][8] because of its special properties and high precision. Current authors have made lots of efforts in developing a Brillouin lidar [9][10][11][12][13][14][15].…”

Comparison of three technique of Brillouin lidar for remote sensing of the ocean

“…made actually achievement in a lidar system using a Br 79 absorption cell and a I 127 absorption cell. Also Walther et al [10,19] made studies on the lidar with edge technique using Faraday anomalous dispersion optical filter (FADOF) and Excited State Anomalous Dispersion Optical Filters (ESFADOF). In fact, in the Hirschberg's lidar system [2], although two F-P etalons were used, it can be actually considered as a kind of edge technique.…”

“…Up to now, there are three techniques for receiving Brillouin lidar echo signal practically: the scanning F-P interferometer (FPI) technique [4,9], the edge technique [7,18,19] and the technique combining F-P etalon and intensified CCD (ICCD) [14]. However, the advantages and disadvantages of every technique have not yet been analyzed, and which one is more suitable for actual application has not yet been discussed.…”