Thermal management of laser diode mode hopping for heat assisted media recording
A method and apparatus provide for determining a temperature at a junction of a laser diode when the laser diode is operated in a lasing state that facilitates heat-assisted magnetic recording, comparing the junction temperature and an injection current supplied during the lasing state to stored combinations of junction temperature and injection current, and determining a likelihood of mode hopping occurring for the laser diode during the lasing state based on the comparison to stored combinations of junction temperature and injection current.
1. An apparatus, comprising:
a slider and a laser diode configured to facilitate heat assisted magnetic recording (HAMR), the slider comprising:
a read element and a write element respectively situated at an air bearing surface (ABS) of the slider;
a near-field transducer (NFT) situated at the ABS proximate the write element;
an optical waveguide configured to couple light from the laser diode to the NFT;
a temperature sensing arrangement configured to calculate a temperature of the laser diode junction based on a voltage differential between a non-steady lasing state of the laser diode and a steady state lasing state of the laser diode; and
a heater arrangement disposed on the slider and configured to heat the junction of the laser diode during at least a portion of the non-lasing state and at least a portion of the lasing state of the laser diode.
2. The apparatus of claim 1 , wherein the heater arrangement and the laser diode define independent circuits.
3. The apparatus of claim 1 , wherein the heater arrangement and the laser diode are configured to be independently controllable.
4. The apparatus of claim 1 , comprising:
a heater control coupled to the heater arrangement; and
a laser control coupled to the laser diode;
wherein the heater control and the laser control define independently controllable circuits.
5. The apparatus of claim 1 , wherein the heater arrangement is electrically coupled to the laser diode.
6. The apparatus of claim 1 , wherein the heater arrangement comprises at least a diode.
7. The apparatus of claim 1 , wherein the heater arrangement comprises a diode in series with a resistive element.
8. The apparatus of claim 1 , wherein the heater arrangement comprises a thermistor.
9. The apparatus of claim 1 , wherein the heater arrangement is configured to heat the laser diode junction to achieve a junction temperature associated with a reduced likelihood of laser diode mode hopping.
10. The apparatus of claim 1 , wherein the heater arrangement is configured to maintain a junction temperature within a predetermined temperature range associated with a reduced likelihood of laser diode mode hopping.
11. An apparatus, comprising:
a slider and a laser diode configured to facilitate heat assisted magnetic recording (HAMR);
a temperature sensing arrangement configured to calculate a temperature of the laser diode junction based on a voltage differential between a non-steady lasing state of the laser diode and a steady state lasing state of the laser diode;
a heater arrangement disposed on the slider and configured to heat the junction of the laser diode during at least a portion of the non-lasing state and at least a portion of the lasing state of the laser diode; and
a controller operatively coupled to the temperature sensing arrangement and the heater arrangement, the controller configured to control heating of the laser diode junction to maintain the laser diode junction temperature within a predetermined temperature range associated with a reduced likelihood of mode hopping of the laser diode.
12. The apparatus of claim 11 , wherein the heater arrangement and the laser diode define independent circuits.
13. The apparatus of claim 11 , wherein the heater arrangement and the laser diode are configured to be independently controllable by the controller.
14. The apparatus of claim 11 , wherein:
the controller comprises:
a heater control configured to control the heater arrangement; and
a laser control configured to control the laser diode; and
the heater control is configured to control the heater arrangement independently of control of the laser diode by the laser control.
15. The apparatus of claim 11 , wherein the heater arrangement is electrically coupled to the laser diode.
16. The apparatus of claim 11 , wherein the heater arrangement comprises at least one of a diode and a thermistor.
17. The apparatus of claim 11 , wherein the heater arrangement comprises a diode in series with a resistive element.
18. An apparatus, comprising:
a slider and a laser diode configured to facilitate heat assisted magnetic recording (HAMR), the slider comprising:
a read element and a write element respectively situated at an air bearing surface (ABS) of the slider;
a near-field transducer (NFT) situated at the ABS proximate the write element;
an optical waveguide configured to couple light from the laser diode to the NFT;
a temperature sensing arrangement configured to determine a temperature of the laser diode junction; and
a heater arrangement disposed on the slider and configured to heat the junction of the laser diode during at least a portion of the non-lasing state and at least a portion of the lasing state of the laser diode.
19. The apparatus of claim 18 , wherein:
the temperature sensing arrangement is configured to calculate a temperature of the laser diode junction based on a voltage differential between a non-steady lasing state of the laser diode and a steady state lasing state of the laser diode; and
the heater arrangement comprises one or both of a resistive element and a diode.
20. The apparatus of claim 18 , comprising:
a heater control coupled to the heater arrangement; and
a laser control coupled to the laser diode;
wherein the heater control and the laser control define independently controllable circuits.