Magnetic recording laser diode control
AssigneeSeagate Technology LLC
InventorHousan Dakroub
Life of this patent
Estimating the term…
Abstract
Controlling a laser diode involves activating a first current source in preparation for writing to a magnetic recording medium. The first current source applies a threshold current to a laser diode that brings the laser diode close to an operating point. Responsive to a write signal, a second current source is activated that applies a write current to the laser diode. A combination of the write current and the threshold current fully energizes the laser diode and is less than a target recording current. Coincident with the activation of the second current source, a photodiode is activated that is optically coupled to the laser diode. The activated photodiode causes a feedback current to be applied to the laser diode.
Claims20
A method comprising:
- activating a first current source in preparation for writing to a magnetic recording medium, the first current source applying a threshold current to a laser diode that brings the laser diode close to an operating point;
- responsive to a write signal, activating a second current source that applies a write current to the laser diode that, in combination with the threshold current, illuminates the laser diode and is less than a target recording current;
- and
- coincident with the activation of the second current source, activating a photodiode that is optically coupled to the laser diode, the activated photodiode causing a feedback current to be applied to the laser diode.
An apparatus comprising:
- a first current source that, in preparation for writing to a magnetic medium, applies a threshold current to a laser diode that brings the laser diode close to an operating point;
- a second current source that, responsive to a write signal, applies a write current to the laser diode in combination with the threshold current so that less than a target recording current is applied to the laser diode;
- and
- an amplifier that receives, from a photodiode optically coupled to the laser diode, a feedback signal that is proportional to an energy output of the laser diode, and responsive to the write signal, applies a feedback current to the laser diode coincident with the applying of the write current.
A system comprising
- a slider comprising a laser diode and a photodiode optically coupled to the laser diode;
- and
- a control circuit comprising:
- a first current source that applies a threshold current to the laser diode that brings the laser diode close to an operating point;
- a second current source that applies a write current in combination with the threshold current to the laser diode, the combination of the write current and the threshold current illuminating the laser diode and are less than a target recording current;
- an amplifier having an input coupled to the photodiode and an output applying a feedback current to the laser diode;
- a write-ready signal line coupled to activate the first current source in preparation for activating the laser diode;
- and
- a write signal line coupled to activate the feedback current coincident with activating the second current source to energize the laser diode.
Dependencies are inferred from the claim text.