Terahertz wavelength-division multiplexing sensor based on a multi-channel waveguide leaky-wave antenna

Although terahertz waveguide sensors have the potential for high sensitivity, their single-channel architecture severely limits detection throughput and multi-parameter parallel analysis capabilities. This paper proposes and implements a terahertz wavelength-division multiplexing sensor based on spatial–spectral mapping, centered on a parallel-plate waveguide leaky-wave antenna integrated with a gradient slit array. By optimizing the waveguide structural parameters, we achieved low crosstalk and frequency tuning for multi-channel signals. The research system verified the sensor’s parallel detection capability and channel independence. When the samples are applied to the slit region of the output plate, the sensor’s individual channels exhibited an intensity modulation sensitivity of 1.2%/(mg/mL) and a frequency sensing sensitivity of 0.57 GHz/(mg/mL). When the sample is placed between the waveguide plates, the sensitivities are 1.6%/(mg/mL) and 0.2 GHz/(mg/mL). Moreover, only the slit channels corresponding to the sample-covered areas showed characteristic frequency shifts, while signals from uncovered channels remained stable, demonstrating the spatial independence of each sensing channel. This work provides practical support for developing the next generation of high-throughput, chip-integrated terahertz sensing systems, which establishes a new pathway toward multi-target analysis and real-time monitoring for biomedical, environmental, and industrial applications.