VCSEL Orientation in Chip-Scale Atomic Clocks
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Solution Overview
Problem
Chip-Scale Atomic Clocks (CSACs) face instability due to optical feedback from partially reflective surfaces, which causes variations in the optical beam and clock frequency, making it difficult to maintain stable wavelength and output power.
Innovation Solution
The method involves positioning components on a scaffolding such that the emitting surface of the laser is non-parallel to the partially reflective surfaces of other components, preventing optical feedback by tilting these surfaces using posts and adhesive materials to direct reflected light away from the laser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If components are positioned with parallel surfaces to simplify assembly, then ease of manufacture is improved, but optical feedback occurs causing wavelength and power instability
Solution Approach 1:
The patent introduces asymmetric positioning by tilting the partially reflective surface at a specific angle (e.g., 5-15 degrees) relative to the laser emitting surface. This asymmetric orientation prevents parallel reflection paths that cause optical feedback, while still allowing for simplified assembly through the use of a standardized scaffolding structure with pre-defined tilt angles.
Solution Approach 2:
The patent employs an intermediary scaffolding structure that provides mechanical support and precise angular positioning between the laser and other components. This intermediary framework eliminates the need for direct parallel alignment, reducing optical feedback while maintaining ease of assembly through modular component mounting.
2Ease of operation
If VCSEL is used to simplify laser alignment, then ease of operation is improved, but optical feedback from reflective surfaces causes frequency instability
Solution Approach 1:
The VCSEL is positioned on a scaffolding structure that provides asymmetric angular offset between the VCSEL emitting surface and partially reflective surfaces. This built-in asymmetry prevents feedback paths while maintaining the ease of operation benefits of VCSEL technology, as the angular relationship is fixed during manufacturing rather than requiring precise alignment during operation.
Solution Approach 2:
The scaffolding structure is pre-configured with specific angular relationships and component positions during manufacturing. This preliminary action of establishing correct geometric relationships before operation eliminates the need for complex alignment procedures while preventing optical feedback that would otherwise cause frequency instability.
3Productivity
If multiple components are integrated on a compact scaffolding to reduce size, then productivity is improved, but optical feedback paths increase causing noise and frequency variations
Solution Approach 1:
The patent utilizes three-dimensional spatial arrangement on the scaffolding, positioning components at different heights and angular orientations rather than simple planar integration. This dimensional approach allows high integration density while ensuring that reflected light from multiple components does not return to the VCSEL, maintaining optical signal stability.
Solution Approach 2:
Each component on the compact scaffolding is positioned with asymmetric angular relationships to the VCSEL emitting surface. This systematic asymmetry prevents optical feedback paths even in the compact multi-component configuration, allowing high integration density without compromising signal stability.
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 approach maintains stable wavelength and output power, reducing frequency variations and enhancing the reliability of CSACs by eliminating damaging optical feedback.
Implementation Method 1
The optical beam emitted from the laser reflects off of several partially reflective surfaces in the CSAC. If any portion of the optical beam emitted by the laser is reflected off of one of the several partially reflective surfaces in the CSAC back into the laser, the wavelength and/or the output power level of the laser is altered due to optical feedback effects.
Data Source
AI summary
A method to construct a chip-scale atomic clock is provided. The method comprises providing a scaffolding for components in a chip-scale atomic clock. The components include a laser and at least one other component. The method also includes operationally positioning the components on the scaffolding so that an emitting surface of the laser is non-parallel to partially reflective surfaces of the at least one other component.