Enhancing frequency accuracy of linear frequency-modulated BOTDR using Richardson-Lucy deconvolution

In Brillouin optical time-domain reflectometry (BOTDR), linear frequency-modulated (LFM) pump pulses have been employed to achieve rapid measurements. However, the linear frequency-time mapping is valid only within the pulse width, which constrains the maximum detectable event zone length with temperature/strain variations. To overcome this limitation, we propose a novel two-step Richardson-Lucy (RL) deconvolution-based algorithm operating in the frequency domain to compress the spectral bandwidth and accurately extract the Brillouin frequency shift (BFS) when the event zone length exceeds the detection constraint. Experimental results demonstrate a 13.5-times reduction in spectral bandwidth from ∼540 MHz to ∼40 MHz. Our proposed method achieves 0.34 MHz BFS measurement accuracy, representing a 4.2-times improvement over the conventional peak-search measurement approach.