Nanometer-Scale Vibration Measurement Using an Optical Quadrature Interferometer based on 3 × 3 Fiber-Optic Coupler

Area of Science:

• Optics and Photonics
• Metrology
• Nanotechnology

Background:

• Accurate measurement of nanometer-scale displacement and vibration is crucial for various scientific and industrial applications.
• Traditional interferometric systems can be affected by system parameter variations, limiting measurement precision.

Purpose of the Study:

• To develop a robust nanometer-scale displacement and vibration measurement system.
• To implement a post-processing technique for accurate characterization of interferometric systems.
• To overcome limitations caused by detector gain inequalities and phase variations in fiber-optic couplers.

Main Methods:

• Utilized an optical quadrature interferometer with a 3x3 fiber-optic coupler.
• Reconstructed complex interference signals from two measured signals.
• Employed Lissajous curve analysis by fitting to an ellipse to extract system parameters.
• Applied post-processing techniques to correct for system imperfections.

Main Results:

• Successfully reconstructed the entire complex interference signal.
• Identified and corrected for unequal detector gains and non-uniform intrinsic phases.
• Demonstrated nanometer-scale measurement capability.
• Measured a 20 kHz sinusoidal vibration with 1.5 nm amplitude and 0.4 nm standard deviation.

Conclusions:

• The proposed optical quadrature interferometer and post-processing technique enable accurate nanometer-scale displacement and vibration measurements.
• Lissajous curve analysis effectively characterizes and corrects for system imperfections.
• The system offers a reliable solution for high-precision metrology.