Hundred-Channel, High-Speed, and Large-Capacity FBG Demodulation Based on an Amplified Tunable Laser

To address the limitation on channel scalability in high speed multi-channel fiber Bragg grating (FBG) demodulation systems caused by insufficient output power of tunable semiconductor lasers, this paper proposes an FBG demodulation system based on laser power amplification. The system employs an MG-Y laser modulated at 2.5 kHz as the seed light, which is then amplified by a single-pass forward-configuration erbium-doped fiber amplifier (EDFA). Through optimization of the pump power, seed injection power, and Er-doped fiber length, the seed light power is amplified from 0.4 mW to 80 mW. To evaluate the suitability of the amplified source in high-speed demodulation, a MEMS optical switch is introduced for synchronous channel switching and spectral acquisition, allowing comparative analysis of the spectral characteristics between the seed and amplified light. Experimental results demonstrate that the amplified source maintains the rapid response time of 400 μs and wavelength stability of ±1 pm. The proposed amplification method significantly enhances output power while preserving high-speed tuning capability and spectral integrity. Through high-speed sensing experiments, it is verified that a demodulation system with an 80 mw tunable laser can achieve 200 channel sensing measurements by adding beam channels and PD. This work resolves the challenge of balancing high speed and large capacity in FBG sensing technology, achieving a 200-channel sensing capacity while operating at a high modulation rate of 2.5 kHz.