Slope-assisted Brillouin optical correlation-domain reflectometry (SA-BOCDR) is one of the high-speed distributed strain sensing techniques, but its strain dynamic range has been limited to approximately 0.15%, which is far from being sufficient for some practical applications. In this paper, we clarify that, unlike widely used time-domain techniques, SA-BOCDR has a trade-off relation between the strain dynamic range and the spatial resolution. This trade-off originates from the unique bell-shaped noise floor inherently involved in the Brillouin gain spectrum observed with correlation-domain techniques. We experimentally show that, at the cost of three times lowered spatial resolution, the strain dynamic range of >0.6% can be achieved.
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