Thermal compensation for laser in heat assisted magnetic recording

A storage drive having a laser for heat assisted magnetic recording, the storage drive comprising:

• a laser preamplifier;
• a storage medium;
• a read channel having,
• a clock pulse counter configured to measure a duration that the laser which heats a spot on the storage medium is in an active or inactive operational state;
• a set of controller components configured to adjust a thermal compensation value based on the duration that the laser is in the active or inactive operational state, the thermal compensation value indicative of a history of durations that the laser was in the active or inactive operational state;
• and
• a channel driver coupled to output to the laser preamplifier a signal based on the thermal compensation value to drive the laser to heat the spot on the storage medium;
• and
• a write head configured to apply, while the spot is heated, a magnetic field to the heated spot to write data to the storage medium.

A method of operating a storage drive that implements heat assisted magnetic recording, the method comprising:

• measuring a duration that a heat source which heats a spot on a storage medium is in an active or inactive operational state;
• adjust a thermal compensation value based on the duration that the heat source is in the active or inactive operational state, the thermal compensation value indicative of a history of durations that the heat source was in the active or inactive operational state;
• and
• outputting a signal to a preamplifier of the heat source based on the thermal compensation value to heat the spot on the storage medium.