Near-field Light Device Quantum Dot Sub-wavelength Recording
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Solution Overview
Problem
Current thermally assisted magnetic recording methods using near-field light are inefficient as they cannot concentrate laser light to a size smaller than its wavelength, leading to suboptimal near-field light generation and potential melting of metal conductors, making continuous operation difficult.
Innovation Solution
A near-field light device utilizing quantum dots to generate micro-size near-field light, where a light source is coupled with a quantum dot structure that outputs energy to a metal end, allowing for efficient energy concentration on a nano-spot smaller than the optical diffraction limit, preventing overheating and enabling continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If laser light is concentrated using an objective lens and optical waveguide, then the light can be focused to a small spot, but the spot size cannot be reduced to less than or equal to the wavelength of the laser light
Solution Approach 1:
The patent introduces a metal conductor as an intermediary component between the optical waveguide and the recording medium. The metal conductor converts optical energy to near-field light (evanescent waves) that can be concentrated to sub-wavelength spots. This intermediary transformation enables overcoming the diffraction limit by converting propagating light modes into evanescent modes that decay exponentially and can be confined to sub-wavelength dimensions.
Solution Approach 2:
The patent changes the fundamental parameter of light confinement by transitioning from far-field propagating waves to near-field evanescent waves. This parameter change allows the spot size to be reduced to less than or equal to the wavelength of the laser light, achieving the desired sub-wavelength resolution for magnetic recording.
2Loss of energy
If most of the concentrated laser light is used for near-field light generation, then the efficiency improves, but the metal conductor may melt due to energy concentration
Solution Approach 1:
The patent employs periodic modulation of the laser light intensity and duration to match the thermal response time of the metal conductor and recording medium. By using pulsed or modulated light rather than continuous high-intensity illumination, the system achieves efficient near-field light generation while allowing thermal diffusion to prevent melting of the metal conductor between pulses.
Solution Approach 2:
The patent dynamically adjusts the balance between energy concentration for near-field light generation and thermal management by controlling light pulse duration, intensity, and duty cycle. This dynamic control enables the system to operate in a regime where sufficient energy is delivered for efficient recording while preventing excessive heat accumulation that would cause conductor melting.
3Loss of energy
If energy is concentrated on a micro region to generate near-field light, then the near-field light generation efficiency improves, but the metal conductor melts making continuous drive difficult
Solution Approach 1:
The patent uses periodic pulsing of the laser light source with duty cycles optimized to deliver sufficient energy for near-field light generation during the 'on' periods while allowing thermal dissipation during the 'off' periods. This periodic operation enables continuous drive capability by preventing cumulative heat buildup in the metal conductor while maintaining high efficiency during active recording intervals.
Solution Approach 2:
The patent incorporates preliminary thermal management measures such as thermal insulation layers, heat sinks, or thermal diffusion structures that are pre-configured to manage heat before it accumulates to dangerous levels. These preliminary actions prepare the system to handle the thermal load of continuous operation by providing thermal pathways or isolation mechanisms in advance.
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 near-field light device effectively increases temperature in a region smaller than the wavelength of the light source, enabling precise magnetic recording bits without overheating the metal conductor, thus overcoming the inefficiencies of traditional methods.
Implementation Method 1
a plurality of first quantity dots which are disposed on a first surface in the quantity dot structure and each of which generates near-field light on the basis of light emitted from the light source
Implementation Method 2
The control unit controls the light source to emit the light upon recording the information, thereby increasing temperature of a region of the recording medium based on a size of the output end
Data Source
AI summary
A recording apparatus records information onto a recording medium. The recording apparatus is provided with: a near-field light device; and a control unit for controlling the near-field light device. The near-field light device is provided with: a light source; a quantum dot structure which is laminated on the light source; a plurality of quantity dots which are included in the quantity dot structure and each of which generates near-field light on the basis of light emitted from the light source; and an output end which is configured to output at least one portion of energy of the near-field light to the exterior of the quantity dot structure. The control unit of the recording apparatus controls the light source to emit the light upon recording the information, thereby increasing temperature of a region of the recording medium based on a size of the output end.