<p>A Rayleigh-scattering-based information system (RSIS) processes and conveys information by utilizing Rayleigh scattering, where the probe wave scatters off particles or molecules smaller than its wavelength, often in the context of fiber optics or atmospheric optics, etc. Wide response bandwidth is crucial for high-performance RSISs, yet it is typically constrained by the probe signal’s scan rate, creating a trade-off with detection range and other key parameters. Traditional methods address this by channel multiplexing across distinct frequency bands, which increases available frequency resource consumption. Here, we introduce a co-channel multiplexing technique that significantly expands response bandwidth without requiring additional frequency resources. Central to this approach is the design of orthogonal coded sequences as the probing signal, which are then decoded using dedicatedly-designed mismatched filters. Applied to a Rayleigh-scattering-based distributed acoustic sensing (DAS) system, our method significantly broadens the response bandwidth and amplifies the signal-to-noise ratio (SNR). Experimental results corroborate the theoretical advancements, demonstrating the multiplexing of multiple co-channels and validating the system’s sensing capabilities. This unveils frequency resource utilization and sets the stage for next-generation sensing technologies that demand broadband detection capabilities.</p>