Objective In the fiber grating demodulation system, the light source characteristics of the system demodulation accuracy, long-term stability and dynamic tuning ability has a decisive impact, in which the multi-wavelength light source technology has become a core component to build large-capacity, high-speed multi-channel distributed fiber grating demodulation system. Although the traditional schemes based on tunable lasers and multi-wavelength random fiber lasers are relatively mature, issues such as output power fluctuations and instability caused by mode competition persist. In contrast, the amplified spontaneous emission (ASE) light source has a longitudinal mode-free structure and broad spectral characteristics, while the output wavelength and power have high stability, and the parallel demodulation of sensor arrays can be realized by combining the filter and wavelength-division multiplexing technology, but it faces the problem of output power attenuation in cascaded filters. Therefore, this paper propose a highly stable multiwavelength light source system based on the Fabry-Perot (F-P) etalon with reflective filter seed injection, and adopts the main oscillation power amplification technique to realize the power enhancement of multiwavelength light source. The light source system ensures wavelength and power stability while realizing high-power multi-wavelength output, which is expected to provide technical support for high-capacity and high-precision fiber grating sensing and demodulation system.

Methods To verify the feasibility of achieving high-power multi-wavelength output, this study adopted the system schematic shown in Fig.1. First, based on the coupling theory of optical power transmission equations and erbium-doped fiber amplifier rate equations, we constructed the numerical simulation model shown in Fig.2 using Optisystem software. Second, the optimal system parameters were determined by optimizing the erbium-doped fiber length and pump laser output power, resulting in a stable multi-wavelength output. Finally, a multi-wavelength light source and power amplification system based on ASE light source combined with F-P etalon is constructed (Fig.5), and the system wavelength and power stability tests are carried out to verify its performance.

Results and Discussions The highly stable multi-wavelength light source system based on F-P plasma with reflection filter seed injection mainly consists of an ASE light source, an F-P standard device, a fiber reflector, a 980 nm pump laser, an erbium-doped fiber, a fiber isolator, a fiber circulator, a gain-flattening filter, and a wavelength division multiplexer. First, a multiwavelength light source and power amplification system based on ASE light source and F-P plasma was constructed according to the system schematic shown in Fig.1. Second, by optimizing the length of the erbium-doped fiber and the output power of the pump laser, a power output of 8.577 dBm was achieved, with a power amplification of 20 times compared with that of the seed light, and the multi-wavelength spectral spacing of the output of the system was 0.808 nm with a flatness of 1.15 dB (Fig.7). Finally, the power and wavelength stability of the multi-wavelength light source were tested. The experimental results show that the average power of the seed light output is −4.449 dBm and the peak fluctuation is less than 0.0049 dB in 120 min; the average power of the multiwavelength light source after seed light injection is 8.577 dBm and the peak fluctuation is less than 0.0067 dB, the power stability is better than 99.91% (Fig.8), and the relative spread of the 3 dB bandwidth is less than 0.01% (Fig.9), and the wavelength drift is less than 0.35 pm (Fig.10), which meets the stability requirements of high-precision multi-wavelength interferometry.

Conclusions An F-P standard highly stable multiwavelength light source scheme based on reflection filter seed injection is proposed and experimentally verified. The feasibility of the system is verified by theoretical simulation analysis, and the multiwavelength light source and power amplification system are constructed to complete the power and wavelength stability test of the multiwavelength light source. The experimental results show that the wavelength drift of the system after seed light injection is less than 0.35 pm, the power stability is better than 99.91%, and the relative spread of the 3 dB bandwidth is less than 0.01% within 120 min. In summary, the multiwavelength light source scheme proposed in this paper has the advantages of simple structure, significant increase in output power and good stability. It is expected to be used in spectral analysis, fiber grating sensing and large-scale high-precision fiber grating demodulation system.