Driver current means the working current of the the pump laser, The optical amplifier board amplifies the input signal using the pump laser driven by pump laser working current.

 

Backlight current means back facet current. It is current O/E converted from part of light reflected from the resonant cavity of a laser. The back facet current reflects the laser output optical power value.

The BCV is a specific to weight pump laser back facet current. If the BCVCUR is 0, the laser is faulty. In this case, replace the board where this faulty laser resides in. 
 
Cooling current is applied to control the temperature of the optical module. In the case of excessively low temperature, the cooling current is increased to make the temperature higher. In the case of excessively high temperature, the cooling current is decreased to make the temperature lower.