Thermal management of laser diode mode hopping for heat assisted media recording
First Claim
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1. A method, comprising:
- 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 to the laser diode during the lasing state to stored combinations of junction temperature and injection current;
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; and
heating the laser diode during the non-lasing state, wherein heating the laser diode comprises;
measuring a temperature of the junction of the laser diode when in the lasing state and in the non-lasing state; and
applying a drive signal to a heating arrangement coupled in a parallel relationship with the laser diode, wherein the heating arrangement comprises at least a diode configured to be reverse biased during the lasing state and forward biased during the non-lasing state.
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Abstract
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.
40 Citations
17 Claims
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1. A method, comprising:
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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 to the laser diode during the lasing state to stored combinations of junction temperature and injection current; 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; and heating the laser diode during the non-lasing state, wherein heating the laser diode comprises; measuring a temperature of the junction of the laser diode when in the lasing state and in the non-lasing state; and applying a drive signal to a heating arrangement coupled in a parallel relationship with the laser diode, wherein the heating arrangement comprises at least a diode configured to be reverse biased during the lasing state and forward biased during the non-lasing state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus comprising:
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a laser diode configured to facilitate heat assisted magnetic recording in a lasing state; a sensor configured to measure a temperature of a junction of the laser diode; and an analyzer configured to determine a likelihood of mode hopping occurring for the laser diode during the lasing state based on a comparison of the junction temperature and an injection current to stored combinations of junction temperature and injection current; a heater arrangement proximate the laser diode; and a controller configured to activate the heater arrangement to warm the junction and maintain the junction temperature within a predetermined temperature range associated with a reduced likelihood of mode hopping occurring for the laser diode during the lasing state; wherein the heater arrangement is coupled in a parallel relationship with the laser diode, and wherein the heater arrangement comprises one or more of a diode, a diode arranged in series with a thermistor, and a diode arranged in series with a heater. - View Dependent Claims (12)
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13. A method, comprising:
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supplying an injection current to a laser diode; measuring a temperature of the junction of the laser diode when in a lasing state that facilitates heat-assisted magnetic recording; comparing the measured junction temperature and the supplied injection current to the stored combinations of junction temperature and injection current; determining if the measured junction temperature and supplied injection current comprises a combination for which mode hopping is likely to occur based upon the comparisons to stored combinations of junction temperature and injection current; and implementing one or more measures to attenuate the effects of or reduce the likelihood of mode hopping during heat-assisted recording; wherein the step of monitoring the junction temperature utilizes a sensor that is positioned to heat the laser diode during a non-lasing state. - View Dependent Claims (14, 15)
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16. A method, comprising:
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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 to the laser diode 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; wherein the step of determining the temperature at the junction comprises; determining a voltage differential between a non-steady lasing state of the laser diode and a steady state lasing state of the laser diode; and calculating the temperature based on the voltage differential.
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17. A method, comprising:
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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 to the laser diode during the lasing state to stored combinations of junction temperature and injection current; 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; and rewriting a sector of data recorded in a magnetic recording medium in response to determining that mode hopping was likely to have occurred.
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Specification