Energy-assisted magnetic recording data storage device with opportunistic boosted laser pre-biasing
Various illustrative aspects are directed to a data storage device including one or more disks, an actuator mechanism configured to position a selected head among one or more heads proximate to a corresponding disk surface among the one or more disks, the selected head comprising a write element and an assistive energy emitter, and one or more processing devices configured to, individually or in combination: apply an assistive energy current to the assistive energy emitter while refraining from applying a write current to the write element, and vary a level of the assistive energy current over time while refraining from applying the write current to the write element.
1. A data storage device, comprising:
one or more disks;
an actuator mechanism configured to position a selected head among one or more heads proximate to a corresponding disk surface among the one or more disks, the selected head comprising a write element and an assistive energy emitter; and
one or more processing devices configured to, individually or in combination:
apply an assistive energy current to the assistive energy emitter while refraining from applying a write current to the write element, and
vary a level of the assistive energy current over time while refraining from applying the write current to the write element.
2. The data storage device of claim 1 , wherein applying the assistive energy current to the assistive energy emitter while refraining from applying the write current to the write element comprises applying a boosted pre-bias current to the assistive energy emitter while refraining from applying the write current to the write element, the boosted pre-bias current being equal to or greater than a nominal write laser current applied during write operations using the selected head.
3. The data storage device of claim 1 , wherein:
the selected head further comprises an assistive energy interface operatively coupled to the assistive energy emitter; and
the one or more processing devices are further configured to, individually or in combination, apply the assistive energy current to the assistive energy emitter while the assistive energy interface is positioned proximate to an area preceding a servo pattern of the corresponding disk surface.
4. The data storage device of claim 3 , wherein the area preceding the servo pattern comprises a write-to-read recovery (WRR) area between a data sector and the servo pattern.
5. The data storage device of claim 4 , wherein the area preceding the servo pattern additionally comprises an unused gap in a data sector between an end of data in the data sector and a beginning of the WRR area.
6. The data storage device of claim 3 , wherein the one or more processing devices are further configured to, individually or in combination, vary the level of the assistive energy current such that the level of the assistive energy current increases linearly or decreases linearly through at least a portion of the area preceding the servo pattern.
7. The data storage device of claim 3 , wherein the one or more processing devices are further configured to, individually or in combination, vary the level of the assistive energy current such that the level of the assistive energy current increases in a stepwise manner or decreases in a stepwise manner through at least a portion of the area preceding the servo pattern.
8. The data storage device of claim 3 , wherein the one or more processing devices are further configured to, individually or in combination, vary the level of the assistive energy current such that the level of the assistive energy current changes in a non-linear manner through at least a portion of the area preceding the servo pattern.
9. The data storage device of claim 1 , wherein the one or more processing devices are further configured to, individually or in combination, vary the level of the assistive energy current over time while refraining from applying the write current to the write element based on optimizing performance constraints.
10. The data storage device of claim 1 , wherein:
the one or more processing devices are further configured to, individually or in combination:
detect a smear on an assistive energy interface operatively coupled to the assistive energy emitter; and
in response to detecting the smear, increase the level of the assistive energy current to a magnitude that positions the selected head at a smear removal fly height below a nominal write fly height.
11. A method comprising:
applying, by one or more processing devices individually or in combination, an assistive energy current to an assistive energy emitter comprised in a selected head of a data storage device while applying a write current to a write element comprised in the selected head, and while the write element is positioned proximate to a data sector;
powering down, by the one or more processing devices individually or in combination, the write current after finishing writing to the data sector; and
applying, by the one or more processing devices individually or in combination, the assistive energy current to the assistive energy emitter at varying levels over time while refraining from applying the write current to the write element.
12. The method of claim 11 , wherein the applying the assistive energy current to the assistive energy emitter at varying levels over time comprises linearly increasing or linearly decreasing a magnitude of the assistive energy current while refraining from applying the write current to the write element.
13. The method of claim 11 , wherein the applying the assistive energy current to the assistive energy emitter at varying levels over time comprises changing a magnitude of the assistive energy current in a non-linear manner while refraining from applying the write current to the write element.
14. The method of claim 11 , wherein the applying the assistive energy current to the assistive energy emitter at varying levels over time is based on optimizing performance constraints.
15. The method of claim 11 , further comprising:
detecting, by the one or more processing devices individually or in combination, a smear on an assistive energy interface operatively coupled to the assistive energy emitter; and
in response to the detecting the smear, increasing the assistive energy current, by the one or more processing devices individually or in combination, to a level that positions the selected head at a smear removal fly height below a nominal write fly height.
16. One or more processing devices comprising, individually or in combination:
means for applying an assistive energy current to an assistive energy emitter comprised in a selected head of a data storage device while applying a write current to a write element comprised in the selected head, and while the write element is positioned proximate to a data sector;
means for powering down the write current after finishing writing to the data sector; and
means for applying the assistive energy current to the assistive energy emitter at varying levels over time while refraining from applying the write current to the write element.
17. The one or more processing devices of claim 16 , wherein the means for applying the assistive energy current to the assistive energy emitter at varying levels over time comprises means for linearly increasing or linearly decreasing a magnitude of the assistive energy current while refraining from applying the write current to the write element.
18. The one or more processing devices of claim 16 , wherein the means for applying the assistive energy current to the assistive energy emitter at varying levels over time comprises means for changing a magnitude of the assistive energy current in a non-linear manner while refraining from applying the write current to the write element.
19. The one or more processing devices of claim 16 , wherein the applying the assistive energy current to the assistive energy emitter at varying levels over time is based on optimizing performance constraints.
20. The one or more processing devices of claim 16 , further comprising, individually or in combination:
means for detecting a smear on an assistive energy interface operatively coupled to the assistive energy emitter; and
means for increasing the assistive energy current, in response to the detecting the smear, to a level that positions the selected head at a smear removal fly height below a nominal write fly height.