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Ultra-sensitive focused laser differential interferometer using balanced detection
Optics Letters
|August 15, 2025
Summary
Balanced detection significantly enhances focused laser differential interferometry (FLDI) measurements. This simple method improves signal-to-noise ratio by 30 dB, achieving shot-noise-limited performance for precise optical sensing.
Area of Science:
- Optical Physics
- Interferometry
- Metrology
Background:
- Focused Laser Differential Interferometry (FLDI) is susceptible to laser intensity noise.
- Shot-noise-limited measurements are crucial for high-precision sensing applications.
Purpose of the Study:
- To demonstrate balanced detection as a method to improve FLDI performance.
- To achieve shot-noise-limited measurements in FLDI systems.
Main Methods:
- Implementing balanced detection by separately detecting both polarization components of the signal beam.
- Utilizing differential amplification to cancel common-mode laser-intensity noise.
- Comparing measurements from a modified FLDI with a conventional setup using an ultrasonic source.
Main Results:
- Balanced detection improved the signal-to-noise ratio by 30 dB.
- The modified FLDI achieved shot-noise-limited measurement performance.
- Common-mode laser-intensity noise was effectively cancelled.
Conclusions:
- Balanced detection is a simple and effective technique for enhancing FLDI.
- This method enables shot-noise-limited measurements, advancing precision optical sensing.
