Implementation of externally modulated Brillouin optical correlation-domain reflectometry using single-sideband modulator

Brillouin optical correlation-domain reflectometry (BOCDR) enables distributed strain and temperature measurements along optical fibers with relatively high spatial resolution and random-access capability. Conventional BOCDR systems require sinusoidal frequency modulation of the laser, implemented either by direct or external modulation. When external modulation is employed, double-sideband modulators are often used. However, because a bandpass filter must select only one of the two sidebands, the resulting signal-to-noise ratio tends to be low. Here, we propose and experimentally verify an external-modulation BOCDR scheme that uses a single-sideband modulator instead. By eliminating the need to discard one sideband, this approach improves energy efficiency.