I replaced a 50% pick off BS (BSW11) with 20% one (BSS11).

I checked the reflectivity of them. For BSW11, injection, transmission, reflection powers were 74uW, 42uW, 31uW, respectively. So the reflectivity is 42%.

For BSS11, injection, transmission, reflection powers were 375uW, 293uW, 72uW, respectively. So the reflectivity is 19%.

Both are consistent with the reflectivity for p pol in their specification.