Sensorless monitoring of laser power instability in a heat-assisted magnetic recording head
AssigneeSeagate Technology LLC
InventorsDeclan Macken, Tyler Lenn Perry, Karim Tatah, Andrei Dorobantu, Todd Michael Lammers
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Abstract
A slider configured for heat-assisted magnetic recording includes a laser diode optically coupled to a waveguide of the slider. A power supply is coupled to the laser diode. A preamplifier is coupled to the power supply. The preamplifier is configured to monitor a forward voltage across the laser diode while operating the laser diode at a constant current during a write operation, detect a change in the forward voltage indicative of laser power instability, and generate a signal in response to detecting the forward voltage change.
Claims22
A method, comprising:
- operating a laser diode of a heat-assisted magnetic recording apparatus at a constant current during a write operation;
- monitoring a forward voltage across the laser diode while operating the laser diode at the constant current during the write operation;
- detecting a change in the forward voltage indicative of laser power instability due to mode hopping;
- counting a number of occurrences of the detected forward voltage change;
- and
- taking a corrective action in response to the number of occurrences exceeding a predetermined integer.
An apparatus, comprising:
- a slider configured for heat-assisted magnetic recording;
- a laser diode optically coupled to a waveguide of the slider;
- a power supply coupled to the laser diode;
- a preamplifier coupled to the power supply and the laser diode, the preamplifier configured to:
- monitor a forward voltage across the laser diode while operating the laser diode at a constant current during a write operation;
- detect a change in the forward voltage indicative of laser power instability due to mode hopping;
- generate a signal in response to detecting the forward voltage change;
- count a number of occurrences of the detected forward voltage change;
- and
- take a corrective action in response to the number of occurrences exceeding a predetermined integer.
An apparatus, comprising:
- a slider configured for heat-assisted magnetic recording;
- a laser diode optically coupled to a waveguide of the slider;
- a power supply coupled to the laser diode;
- a preamplifier coupled to the power supply and the laser diode, the preamplifier configured to:
- monitor a forward voltage across the laser diode while operating the laser diode at a constant current during a write operation;
- detect a change in the forward voltage indicative of laser power instability due to mode hopping;
- and
- generate a signal in response to detecting the forward voltage change, wherein the signal generated by the preamplifier indicates that data needs to be re-written.
An apparatus, comprising:
- a slider configured for heat-assisted magnetic recording;
- a laser diode optically coupled to a waveguide of the slider;
- a power supply coupled to the laser diode;
- a preamplifier coupled to the power supply and the laser diode, the preamplifier configured to:
- monitor a forward voltage across the laser diode while operating the laser diode at each of a plurality of different constant currents during write operations;
- detect a change in the forward voltage indicative of laser power instability due to mode hopping;
- generate a signal in response to detecting the forward voltage change for each of the different constant currents where the forward voltage change is detected;
- and
- determine temperature boundaries for each of the different constant currents where the forward voltage change is detected.
Dependencies are inferred from the claim text.