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Updated: Jul 16, 2025
09:57
Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
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Real-time free spectral range measurement based on a correlated resonance-tracking technology
Optics Express
|September 15, 2023
Summary
This study introduces a new real-time measurement technology for the free spectral range (FSR) of silicon nitride waveguide ring resonators (WRRs). The method achieves high precision and correlates FSR with room temperature, offering a superior approach for low-finesse devices.
Area of Science:
- Photonics
- Optical Engineering
- Materials Science
Background:
- Waveguide ring resonators (WRRs) are crucial optical components.
- Accurate measurement of the free spectral range (FSR) is essential for WRR characterization.
- Existing methods face challenges with noise and low-finesse devices.
Purpose of the Study:
- To present a novel real-time measurement technology for the FSR of ultrahigh-aspect-ratio silicon nitride (Si3N4) WRRs.
- To achieve high precision FSR measurements.
- To demonstrate the correlation between FSR and temperature.
Main Methods:
- Utilizing two optical single-sideband frequency-shifted lights to track correlated resonant modes.
- Employing the Pound-Drever-Hall technique while mitigating interference noise.
- Measuring FSR in the GHz range for a 35 mm Si3N4 WRR.
Main Results:
- Achieved a relative precision of 0.1474 ppm for FSR measurement.
- Measured an FSR of 1,844,944.5 kHz and finesse (F) of 13.2.
- Demonstrated a high cross-correlation (0.913) between FSR-calculated and thermistor-measured temperatures.
Conclusions:
- The developed technology offers a precise and reliable method for real-time FSR measurement.
- The technology shows a strong correlation between FSR and room temperature.
- This method is optimal for real-time FSR measurements of low-finesse (F < 50) devices in the GHz range.
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