This study reports a simple and cost-effective post-lithography solution for reducing the characteristic dimensions of structures on the nanometer scale using an external mechanical force without any modification of the existing exposure system. In particular, this study presents a tunable aluminum wire grid polarizer (WGP) made by a laser interference lithography and i-line (365 nm) exposure setup on polyethylene naphthalate. The WGP achieves a 58% maximum linewidth shrinkage of the metal nanowire on the polymer substrate, and further improved the polarization extinction ratio by 83% with a defined operation window and optimized strain. The simulations in this study prove the rise of the extinction ratio with the modulation of the WGP pattern. Physical evidence explains the fall of the extinction ratio for both the increase of the metal crack volume and the delaminated randomly oriented fall-on fragments under extensive operation.