dBo and dBe in relation to Watts
dBo = The optical Loss in dB,

dBe = The electrical loss in dB,

This is most notably used in RF over Fiber applications.

1 dBo of Optical loss = 2 dBe of RF Loss, this is due to the fact that the converted RF power is related to the square of the optical power.  Of course this is on the reception side.  Transmission is an inherently low efficiency process so the inverse mapping should not be applied.

They are not directly related to dBm as they are loss factors and are applied equally to all power measures.  In other words they are not referenced to anything but are scaling factors.