relative polarization state of the interfering modes therefore this also translates into polarization dependent loss pdl degradation for example when constructing sfp voa prototypes using standard smf28 fibers we measured pdl levels above 1 db at 20 db attenuation a summary of this data is provided in fig6 the pdl performance measured on these prototypes are significantly worse than what is typically measured on a stand alone pigtailed es voa which would be expected to be 0 3 db maximum at 20 db attenuation particularly at high attenuation a proportionally larger optical power exists in the cladding modes which increases modal interference effects and translates into higher levels of pdl with reference to fig9 a and 9b a cladding mode suppressing fiber was used for both the input optical fiber 92 and the output optical fiber 98 of an es voa component 90 in accordance with the present invention in an effort to suppress the cladding modes in the short output optical fiber 98 and thereby improve the pdl and wdl performance of the es voa component 90 packaged in a sfp housing 30 for the prototype a double clad fiber was used for both the input optical fiber and the output optical fiber though the optical power in the cladding of the input fiber is significantly less than in the output fiber the input fiber is also a possible contributing source of modal interference hence using a cladding.