VCSELs not permitted in TIA or IEC for optical loss testing
VCSELs are not permitted for optical loss testing to ANSI/TIA-568.3-E, ISO/IEC 11801 or EN50173. In addition, if you are applying for a cabling warranty, the cabling vendor offering the warranty will most likely reject the results.
That's because VCSELs do not meet the spectral width requirements of ANSI/TIA-526-14-C and IEC 61280-4-1 (shown below). In previous standards, there was text allowing the user to use VCSEL sources as an option. That is no longer the case due to the measurement uncertainty associated with VCSELs.
ANSI/TIA-526-14-C and IEC 61280-4-1
5.2.2 Spectral characteristics
The spectral width of the light source shall meet the requirements of Table 3 when measured in accordance with IEC 61280-1-3.
The spectral width of a VCSEL is around 0.65 nm, nowhere near the 30 nm to 60 nm requirement in Table 3 above.
VCSEL: Vertical Cavity Surface Emitting Laser