Chip-Scale Atomic Clocks Using LED Light Sources
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Solution Overview
Problem
Chip-scale atomic clocks using vertical cavity surface emitting lasers (VCSELs) face high implementation costs and require precise control to maintain stability, with 'burn-in' times being lengthy due to power changes over time, and finding optimal operating points for VCSELs is challenging, whereas other components like oscillators or vapor cells are mass-produced at lower costs.
Innovation Solution
The use of light emitting diodes (LEDs) or quantum dot lasers as light sources in conjunction with a narrowband optical filter and a resonance vapor cell, optionally with a filter cell, to illuminate and detect hyperfine transition frequencies, along with a magnetic shield to minimize magnetic field effects, allowing for lower-cost construction and simpler package designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VCSELs are used as light sources in atomic clocks, then frequency stability can be achieved, but implementation cost and device complexity increase significantly
Solution Approach 1:
The patent replaces expensive VCSELs with LEDs that have broader spectral width but can be mass-produced at lower cost. The system uses a filter cell with vapor atoms to select the narrow spectral line needed for atomic resonance, eliminating the need for costly VCSELs while maintaining frequency stability
Solution Approach 2:
The patent introduces a filter cell containing vapor atoms as an intermediary between the LED light source and the atomic clock mechanism. This filter cell selectively transmits only the narrow spectral line resonant with the atomic transition, allowing LEDs to replace VCSELs while maintaining the required spectral precision
2Reliability
If VCSELs are used to achieve precise frequency control, then clock stability improves, but burn-in time and manufacturing cost increase
Solution Approach 1:
The patent substitutes VCSELs with LEDs that do not require lengthy burn-in periods. LEDs can be mass-produced and used immediately without the days or weeks of stabilization time required for VCSELs, significantly improving manufacturing efficiency while maintaining clock stability through the filter cell mechanism
Solution Approach 2:
The system uses the atomic vapor in the filter cell to automatically select and stabilize the spectral line, eliminating the need for complex electronic control and lengthy burn-in procedures required by VCSELs to achieve frequency stability
3Measurement precision
If narrow spectral linewidth is maintained for frequency stability, then clock precision improves, but laser power control and operating point optimization become more difficult
Solution Approach 1:
The patent uses the atomic vapor filter cell as an intermediary that passively selects the narrow spectral line through atomic resonance absorption. This eliminates the need for complex electronic control systems to maintain narrow linewidth and optimize operating points, as the atoms themselves perform the spectral selection
Solution Approach 2:
The atomic vapor in the filter cell automatically performs spectral line selection through its natural resonance properties, eliminating the need for external control mechanisms to maintain frequency precision. The system self-regulates the spectral width through the atomic transition itself
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 enables the development of cost-effective chip-scale atomic clocks with stable frequency performance, potentially reaching fractional frequency stability of 10−11 at 1 hour, reducing stringent laser spectrum stability requirements and eliminating lengthy burn-in times, while allowing for simpler designs compared to conventional laser-based systems.
Implementation Method 1
a light source configured to illuminate a resonance vapor cell... the light source comprises a light emitting diode configured to illuminate the resonance vapor cell
Implementation Method 2
the light source comprises a quantum dot laser configured to illuminate the resonance vapor cell
Implementation Method 3
the resonance vapor cell is configured to emit a signal corresponding to a hyperfine transition frequency in response to illumination from the light source
Implementation Method 4
a filter cell disposed between the light source and the resonance vapor cell and configured to generate optical pumping
Implementation Method 5
a narrowband optical filter disposed between the light source and the resonance vapor cell and arranged such that light emitted from the light source passes through the narrowband optical filter
Data Source
AI summary
According to some aspects of the present disclosure, an atomic clock and methods of forming and/or using an atomic clock are disclosed. In one embodiment, an atomic clock includes: a light source configured to illuminate a resonance vapor cell; a narrowband optical filter disposed between the light source and the resonance vapor cell and arranged such that light emitted from the light source passes through the narrowband optical filter and illuminates the resonance vapor cell. The resonance vapor cell is configured to emit a signal corresponding to a hyperfine transition frequency in response to illumination from the light source, and a filter cell is disposed between the light source and the resonance vapor cell and configured to generate optical pumping. An optical detector is configured to detect the emitted signal corresponding to the hyperfine transition frequency.