On an ESFADOF edge-filter for a range resolved Brillouin-lidar: The high vapor density and high pump intensity regime
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- Popescu, A. & Walther, T. Appl. Phys. B (2010) 98: 667. doi:10.1007/s00340-009-3857-5
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The temperature profile in the upper ocean mixed layer is of great interest for oceanography, weather forecast and climate studies—especially regarding the strong coupling between the atmosphere and the ocean. A lidar system based on Brillouin-scattering can provide such data over an extended region of the ocean. In this paper we report on studies of an excited-state Faraday anomalous dispersion optical (ESFADOF) edge-filter that, when employed as a receiver in a Brillouin-lidar, will enable range-resolved remote measurements from mobile platforms. We focus on the transmission of such a filter operating on the 5P3/2→8D5/2 Rb transition (543.30 nm), and its dependence on the vapor density in the high pump intensity regime. Due to quenching processes such as energy-pooling enhanced by nonlinear radiation trapping, as well as plasma formation, a limit on the lower ESFADOF level number density exists. Beyond this threshold the achievable ESFADOF transmission is limited to a few percent. However, our studies show for the first time measured ESFADOF spectra with steep transmission edges with a transmission change of 15% within a few gigahertz.