Disk drive calibrating fly height actuator to enable laser biasing during non-write mode

A disk drive is disclosed comprising a disk, a head comprising a laser operable to heat the disk while writing data to the disk, and a fly height actuator (FHA) operable to actuate the head vertically over the disk. A setting is applied to the FHA to maintain a fly height of the head. An approximately zero bias laser power is applied to the laser during a non-write mode, and a first write laser power is calibrated during a write mode. A non-zero bias laser power is applied to the laser during the non-write mode, and a second write laser power is calibrated during the write mode. When the second write laser power is different than the first write laser power, the setting of the FHA is adjusted to adjust the fly height of the head.