Design of High-Precision Parallel AWG Demodulation System

Area of Science:

• Photonics and Optical Engineering
• Signal Processing
• Fiber Optic Sensing

Background:

• Arrayed waveguide gratings (AWGs) are crucial for wavelength-selective optical signal processing.
• High-precision demodulation is essential for advanced fiber Bragg grating (FBG) sensing applications.
• Existing methods face challenges in achieving high accuracy and dynamic range simultaneously.

Purpose of the Study:

• To develop and validate a high-precision demodulation method for AWG-based systems.
• To enhance the interrogation precision and dynamic range for FBG sensing.
• To demonstrate the effectiveness of a novel channel decoupling technique.

Main Methods:

• Implementation of a hybrid AWG system with a 1x8 primary filter (0.5 nm spacing) and a 1x4 auxiliary filter (1 nm spacing).
• Development of an innovative three-channel decoupling technique (two primary, one auxiliary).
• Extensive simulations to evaluate spectral characteristics and demodulation performance.

Main Results:

• Achieved interrogation precision of 8 pm with a dynamic range of 0.4 nm.
• Simulated AWG transmission spectra show crosstalk below -24.8 dB and non-uniformities below 0.8 dB.
• Insertion loss remained below -3.7 dB, with 3 dB and 10 dB bandwidths of 0.25 nm and 0.43 nm, respectively.

Conclusions:

• The proposed demodulation method significantly improves interrogation precision for FBG sensing using AWG systems.
• The novel channel decoupling approach enables high-accuracy spectral analysis.
• The method offers a robust solution for demanding optical sensing applications.