Abstract
In this paper, we analyze the performance of an all-fiber, micropulse, 1.5 μ m coherent lidar for remote sensing of atmospheric temperature. The proposed system benefits from the recent advances in optics/electronics technology, especially an all-fiber image-reject homodyne receiver, where a high resolution spectrum in the baseband can be acquired. Due to the presence of a structured spectra resulting from the spontaneous Rayleigh-Brillouine scattering, associated with the relevant operating regimes, an accurate estimation of the temperature can be carried out. One of the main advantages of this system is the removal of the contaminating Mie backscatter signal by electronic filters at the baseband (before signal conditioning and amplification). The paper presents the basic concepts as well as a Monte-Carlo system simulation as the proof of concept.
Highlights
Continuous high-resolution observation of atmospheric temperature profile in the troposphere is crucial for improved weather forecasting at the mesoscale [1]
In light of Rye’s [7] results, we have shown that it is possible to use a micropulse 1.5μm coherent temperature lidar (CTL) to carry out an accurate remote sensing of temperature in the lower atmosphere
In our simulation the combined effects of Mie and molecular backscattering are taken into account
Summary
Continuous high-resolution observation of atmospheric temperature profile in the troposphere is crucial for improved weather forecasting at the mesoscale [1]. The majority of existing temperature measurement lidars benefit from the direct detection principle In these systems sub-micron wavelengths are employed to take advantage of a stronger Rayleigh backscatter, where β ∝ λ−4 (β is the molecular backscatter cross-section and λ is the wavelength). Optical image-reject downconversion of Doppler signals to baseband, essential for resolving positive and negative frequency shifts, has not been practically demonstrated, viz., not until recently [8] This is an essential part of the proposed CTL to circumvent the restrictions imposed by the available BW of ADCs and PDs. The alternative, and conventionally employed, down-conversion to intermediate frequency (IF) band, places unrealistic requirements on the BW of the PDs and ADCs. A successful prototyping of an allfiber image-reject homodyne receiver demonstrated by Abari et al [8] facilitates the realization of a molecular backscatter CTL as suggested in this paper
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