Novel gas sensor combined active fiber loop ring-down and dual wavelengths differential absorption method

Area of Science:

• Optics
• Spectroscopy
• Gas Sensing

Background:

• Traditional gas sensors face challenges with cavity loss variations and electronic drift.
• Accurate gas concentration measurements are crucial for environmental monitoring and industrial safety.

Purpose of the Study:

• To develop a novel active fiber loop ring-down gas sensor.
• To improve gas detection precision by mitigating system instabilities.

Main Methods:

• Employed dual wavelengths from Distributed Feedback Laser Diodes (DFB LDs) for differential absorption.
• Utilized an Erbium Doped Fiber Amplifier (EDFA) with Automatic Gain Control (AGC) to maintain cavity performance.
• Incorporated fiber Bragg gratings (FBGs) to filter out amplified spontaneous emission (ASE) noise.

Main Results:

• The sensor demonstrated high precision, with a relative deviation less than ±0.4% for 0.1% ethyne detection under varying cavity loss.
• Long-term stability was confirmed, showing a relative deviation less than ±0.5% over 24 hours.
• The dual-wavelength method effectively eliminated influences from cavity loss and photoelectric device drift.

Conclusions:

• The proposed active fiber loop ring-down gas sensor with dual wavelengths offers a robust and precise method for gas detection.
• This technique significantly enhances accuracy and stability compared to traditional single-wavelength approaches.
• The system shows promise for reliable ethyne monitoring in various applications.