Positive-Bias Laser Driver for Dark Heating Without Mode Hopping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) drives face issues with mode hopping due to temperature-induced changes in laser diodes, leading to inconsistent heating and reduced recording performance, as the laser diodes switch between different lasing modes, affecting the reliability and effectiveness of data recording.
Innovation Solution
A novel dark laser heating (DLH) technique using an asymmetric BiCMOS laser diode driver generates bias pulses to preheat the laser diode to a target temperature without optical output, employing programmable parameters to control the duration and amplitude of current pulses, preventing mode hopping and ensuring consistent heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the laser diode is used for heat-assisted magnetic recording, then data recording density is improved, but mode hopping occurs due to temperature-induced changes, degrading recording reliability
Solution Approach 1:
The patent applies preliminary action by preheating the laser diode to a target temperature before the actual data writing operation. This preliminary heating stabilizes the laser diode's operating temperature, preventing mode hopping during the critical write operation and ensuring consistent heating of the magnetic media for reliable recording.
Solution Approach 2:
The patent changes the operating parameters of the laser diode by dynamically adjusting the drive current based on temperature feedback. The system monitors the laser diode temperature and modifies the drive parameters to maintain optimal operating conditions, preventing temperature-induced mode hopping and ensuring stable laser output during recording operations.
2Temperature
If the laser diode temperature increases during write operation, then heating effectiveness is improved, but mode hop critical temperatures are crossed, causing mode hopping and reducing write performance
Solution Approach 1:
The patent implements feedback control by monitoring the laser diode temperature and adjusting the drive current accordingly. The system uses temperature information to dynamically modify the laser diode operating parameters, ensuring the temperature remains within a stable range that prevents mode hopping while maintaining effective heating for reliable writing operations.
Solution Approach 2:
The system performs preliminary heating to reach a target temperature before the write operation, then maintains this stable temperature during writing. This preliminary action prevents the laser diode from crossing mode hop critical temperatures during the actual data writing, ensuring consistent write performance.
3Reliability
If dark laser heating is used to preheat the laser diode, then mode hopping is prevented, but additional control complexity is introduced through programmable parameters
Solution Approach 1:
The patent makes the laser diode driver circuit multi-functional by enabling it to perform both normal data writing operations and dark laser heating preheating operations. The same driver circuitry, with programmable control parameters, can switch between different operational modes, reducing the need for separate dedicated circuits and minimizing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The DLH technique stabilizes the laser diode temperature, minimizing mode hopping and enhancing the reliability and performance of heat-assisted magnetic recording by maintaining consistent heating and reducing the risk of data erasure.
Implementation Method 1
applying, using the asymmetric laser diode driver, the at least one bias pulse to the laser diode such that no optical response is produced by the laser diode
Implementation Method 2
a laser diode coupled to a near field transducer (NFT) configured to heat an area of the disk near the read/write head
Implementation Method 3
coupled to a near field transducer (NFT) configured to heat an area of the disk near the read/write head
Data Source
AI summary
Various illustrative aspects are directed to a data storage device comprising a disk, a read/write head configured to read data from and write data to the disk, a laser diode (LD) coupled to a near field transducer (NFT) configured to heat an area of the disk near the read/write head, an asymmetric LD driver configured to drive the LD, and one or more processing devices configured to: preheat the LD to a target temperature, wherein the preheating comprises: generating at least one bias pulse conforming to one or more tunable parameters, based at least in part on the target temperature; and applying, using the asymmetric LD driver, the at least one bias pulse to the LD such that no optical response is produced by the LD; and initiate a write operation for writing data to the disk.