The 8169A Polarization Controller, with single-mode fiber input and output, is used to change light from any polarized or unpolarized light source into any well-defined state of polarization. The design based on bulk-optic zero-order waveplates and a high-performance linear polarizer at the input provides optimum determination and repeatability of polarization states over a wide wavelength range. The 8169A is especially well suited for use together with a tunable laser to make swept-wavelength measurements of the polarization dependence of fiberoptic devices, by setting a set of relatively orthogonal polarization states for Mueller Matrix analysis. These measurements are supported by a Plug&Play driver and coordinated operation of the 8169A with an Keysight tunable laser and power meters can be enhanced with the Photonic Foundations Library software package. The fundamental basis of this flexible instrument also supports many general applications requiring polarization control and analysis.