TAR Slider with Integrated External-Cavity VCSEL and Lateral Waveguide
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Solution Overview
Problem
Integrating a more powerful external-cavity VCSEL laser diode with a length of at least 300 μm into a thermally-assisted recording (TAR) slider is challenging due to mechanical support, electrical connections, and heat sink requirements, while maintaining the existing slider thickness to avoid increasing the disk-to-disk spacing and overall drive size.
Innovation Solution
A TAR slider with an integrated external-cavity VCSEL, where the laser diode is supported by a carrier with a U-shape or L-shape configuration that aligns the laser beam orthogonal to the grating coupler, allowing the laser radiation to be directed into an optical waveguide, and maintains the slider height by using a transparent block attached to the semiconductor substrate, ensuring mechanical support and heat sinking without increasing the slider thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a longer external-cavity VCSEL laser diode (length ≥300 μm) is integrated into the TAR slider to provide sufficient power output (≥50 mW), then the laser power output is improved, but the slider thickness must be increased to accommodate the longer laser diode, which would increase the disk-to-disk spacing and overall drive size
Solution Approach 1:
The patent reorients the laser diode from a longitudinal configuration (aligned with the slider length) to a transverse configuration (aligned with the slider width). The external-cavity VCSEL is positioned at the trailing end of the slider with its cavity axis perpendicular to the slider length, allowing the laser beam to propagate laterally across the slider width. This dimensional reorientation enables integration of the long laser diode without increasing slider thickness, as the extended cavity length now lies in the lateral dimension rather than the thickness dimension.
Solution Approach 2:
The patent introduces a lateral waveguide as an intermediary optical component that transports laser radiation from the transverse laser diode to the near-field transducer (NFT). The waveguide laterally channels the laser beam across the slider body, enabling the laser diode to be positioned at the trailing end while still delivering optical power to the NFT at the leading end. This intermediary structure decouples the physical positioning requirements of the laser diode from the functional requirements of the NFT, allowing integration without increasing slider thickness.
2Reliability
If the slider thickness is increased to accommodate the external-cavity VCSEL, then the laser diode can be properly supported and heat-sinked, but the disk-to-disk spacing increases and the overall drive size increases
Solution Approach 1:
The patent resolves the mechanical support and heat sinking challenge by reorienting the laser diode configuration from longitudinal to transverse. The external-cavity VCSEL is positioned at the trailing end with its cavity axis perpendicular to the slider length, allowing the extended cavity (length ≥300 μm) to extend laterally across the slider width rather than increasing the thickness. This enables the laser diode to be properly mounted and heat-sinked within the existing slider thickness envelope, maintaining compact drive dimensions while ensuring reliable mechanical support and thermal management.
3Ease of manufacture
If a conventional VCSEL with short length (≈100 μm) is used, then the integration with the slider is easier, but the power output (≈10 mW) is insufficient for TAR operations requiring ≥50 mW
Solution Approach 1:
The patent enables integration of the longer external-cavity VCSEL (length ≥300 μm) by reorienting it from a longitudinal to a transverse configuration. The laser diode is positioned at the trailing end of the slider with its cavity axis perpendicular to the slider length, allowing the extended cavity to lie in the lateral dimension. This reorientation maintains integration simplicity by positioning the laser diode at the accessible trailing end while providing the necessary ≥50 mW power output through the extended cavity design, thus resolving the contradiction between ease of integration and power output.
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
Enables the integration of a longer external-cavity VCSEL laser diode within the TAR slider without increasing the slider thickness, providing the necessary power output while maintaining the compact size of the disk drive, thus addressing the mechanical and thermal challenges of integrating more powerful laser diodes.
Implementation Method 1
an optical waveguide having a grating coupler oriented in a plane generally parallel to the slider trailing end
Implementation Method 2
an optical waveguide with a near-field transducer (NFT) directs radiation from a laser to heat localized regions of the magnetic recording layer on the disk
Implementation Method 3
The radiation heats the magnetic material locally to near or above its Curie temperature to lower the coercivity enough for writing to occur
Implementation Method 4
An external-cavity VCSEL is described in U.S. Pat. No. 6,778,582 B1 and by J. G. McInerney, et al., 'High brightness 980 nm pump lasers based on the Novalux Extended Cavity Surface-Emitting Laser (NECSEL) concept'
Data Source
AI summary
A thermally-assisted recording (TAR) slider has an integrated TAR head and an integrated laser diode. The laser diode may be an external-cavity VCSEL that includes a semiconductor substrate with the VCSEL formed on one surface, an external cavity on the opposite surface, and an output third mirror on the output surface of the external cavity. The TAR head is integrated with the slider at the trailing end and includes an optical waveguide having a grating coupler oriented in a plane generally parallel to the slider trailing end, and a near-field transducer (NFT) at the slider air-bearing surface (ABS) and coupled to the waveguide. A carrier is attached to the slider and has a base portion that supports the external-cavity VCSEL so that the linear path of its output laser beam is aligned with and oriented orthogonal to the plane of the grating coupler. The grating coupler receives the laser radiation and turns it 90 degrees into the waveguide, which directs the laser radiation to the NFT at the ABS.