Distributed temperature sensors operating at 840  nm for short-range sensing applications

Raman-based distributed temperature sensor (RDTS) devices have grown dramatically over the past two decades, partially driving the optical sensor industry. Over nearly four decades, most academic investigations about RDTS have focused on developing distributed sensor devices operating at the wavelength of 1550 nm, given the low loss of standard single-mode fibers in this spectral region. Certainly, the wavelength of 1550 nm is ideal for long-range sensing applications. However, at this wavelength, the signal-to-noise ratio (SNR) of RDTS systems is degraded, given the low intensity of the measured signals. Looking for simple solutions to improve the SNR of this sensing technology, we discuss in this paper an RDTS operating at the spectral region of 840 nm as an alternative for short-range distributed temperature sensing applications delivering an improved SNR.