The coupling length of a directional coupler is strongly polarization dependent, especially for use in wave guide tap monitoring applications. To avoid severe polarization and maximize the wavelength flatness of optical waveguide taps, a $12\mathrm{\mu m}$ thick silicon-on-insulator (SOI) platform and Mach–Zehnder directional couplers implemented with the bending effect illustrated low coupling loss to a SMF-28 fiber, low polarization dependence, and insensitive wavelength on the tap port for monitoring applications. Our results demonstrated that the optical waveguide tap, which carries a portion of the light signal, showed a 0.077 coupling ratio and $0.2\mathrm{dB}$ for the polarization-dependent loss. The wavelength variation for the coupling ratio was less than 4% across the entire C-band. A $0.26\mathrm{dB}$ per interface coupling loss was also achieved between the $12\mathrm{\mu m}$ thick SOI waveguide and the SMF-28 fiber.