Range-Adaptive Wavelength Calibration Fusion Method for Enhanced Demodulation Precision of Optical Frequency Domain Reflectometry

Abstract

In the optical frequency domain reflectometry (OFDR) system, laser wavelength drift is a critical issue that undermines measurement precision, necessitating effective wavelength calibration to maintain reliable performance. Traditional wavelength calibration methods are difficult to maintain high demodulation precision over a wide wavelength range using gas cell or Fabry-Pérot (F-P) etalon solely, which is attributed to the limited calibration range of gas cell and the inherent susceptibility to external environment fluctuation of F-P etalon. To achieve both high precision and wide sensing range, this paper proposes a range-adaptive wavelength calibration fusion (RAWCF) method for OFDR. By introducing a spectral overlap factor, the proposed method adaptively fuses the calibration information provided by the gas cell and the F-P etalon. Experimental results demonstrate an average spectral shift demodulation precision of 12.29 pm at a spatial resolution of 5.12 mm when the wavelength varies from 1551 nm to 1579 nm. Moreover, comparative experiments validate that the proposed RAWCF method improves the spectral shift demodulation precision by 5.03-fold and 1.41-fold compared with traditional wavelength calibration using the gas cell alone and the F-P etalon alone, respectively. This approach effectively addresses the inherent difficulty of spectral shift demodulation precision enhancement within wide sensing spectral range relying on the sole wavelength calibration elements of gas cell or F-P etalon, offering a robust solution for high-performance OFDR sensing.