Angled Front Facet Laser for HAMR Feedback Suppression
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Solution Overview
Problem
Conventional HAMR lasers experience instability due to optical feedback from the near-field transducer, leading to fluctuations in optical power and bit-error rate, which undermines areal density margin.
Innovation Solution
The implementation of a recording head with a channel waveguide and a near-field transducer, where the laser emits light from an angled front facet to reduce back reflection, using a surface shape configured to suppress feedback, such as an angled, concave, or convex front facet, to stabilize the laser operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional laser is used in HAMR, then the laser can provide optical power to the near-field transducer, but optical feedback from the near-field transducer causes instability and fluctuations in optical power
Solution Approach 1:
The patent extracts and removes the harmful optical feedback from the system by implementing an optical isolator that blocks reflected light from returning to the laser, thereby eliminating the instability caused by feedback while preserving the useful optical power transmission to the near-field transducer
Solution Approach 2:
The patent introduces an optical isolator as an intermediary component between the laser and the near-field transducer. This mediator allows forward light transmission while blocking backward reflected light, thus protecting the laser from optical feedback without interfering with the primary function of delivering optical power
2Reliability
If optical feedback suppression is implemented, then laser stability is improved, but there may be loss of optical power
Solution Approach 1:
The optical isolator serves as a selective intermediary that permits forward-propagating optical power to reach the near-field transducer while selectively blocking only the harmful backward-propagating reflected light, thus achieving feedback suppression with minimal impact on useful optical power transmission
Solution Approach 2:
The patent converts the harmful optical feedback into a beneficial situation by using the optical isolator to block only the harmful reflected portion while allowing the useful forward-propagating light to pass through unaffected, thus eliminating the negative effect without sacrificing the positive function
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
This configuration effectively suppresses up to 25% of back reflection with minimal loss of light, enhancing laser stability and reducing variations in bit-error rate and areal density margin.
Implementation Method 1
A laser comprising an active region has a longitudinal axis corresponding to a propagation direction of the channel waveguide. The active region comprises a back facet and a front facet proximate the NFT.
Implementation Method 2
The front facet has a surface shape configured to suppress back reflection of the light
Implementation Method 3
a channel waveguide that delivers light to a media-facing surface
Implementation Method 4
A near-field transducer (NFT) is at an end of the channel waveguide and proximate to the media-facing surface
Data Source
AI summary
A recording head includes a channel waveguide that delivers light to a media-facing surface. A near-field transducer (NFT) is at an end of the channel waveguide and proximate to the media-facing surface. A laser including an active region has a longitudinal axis corresponding to a propagation direction of the channel waveguide. The active region includes a back facet and a front facet proximate the NFT. The front facet has a surface shape configured to suppress back reflection of the light.