  Exceptional points (EPs), where eigenvalues and eigenstates coalesce, offer
significant advantages in sensor design. However, the extreme sensitivity near
EPs poses significant challenges due to fabrication errors and system noises,
which degrade sensing performance. To address this, we introduce a novel
approach leveraging the polarization degrees of freedom to achieve controllable
EPs. By expressing tunable polarization as equivalent gain, we establish a
direct relation between the polarization and the phase of the coupled system,
and achieve the polarization-controlled singularity even post-fabrication. The
polarization angle can be utilized as a sensing index, which enables indirect
and accurate measurement near the EPs. The theoretical approach is
experimentally validated using a general design of THz non-Hermitian
metasurface sensors. Our results indicate that this method enhances robustness
and sensitivity, opening new avenues for practical applications in
ultra-sensitive sensing.
