There is no such thing as P-polarizer-sheet or S-polarizer-sheet, but you can use a PBS (polarization beam splitter), which can tell you -roughly- if the light is p-polarized or s-polarized. But still, there are many technical difficulties in your experimental setup: 1. what fiber you are using? PMF (polarization-maintain fiber) can give you a linear polarized output, but the polarization orientation is dependent on your fiber orientation. Rotate your fiber output end and you will get a differen