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High-Precision Fiber Optic Gyroscope (HPFOG) is the core sensor of the long-endurance fiber optic inertial navigation system. The improvement of the positioning accuracy of the inertial navigation system depends on the improvement of the bias performance and the scale performance of the gyroscope. The broadband ASE light source can effectively suppress the noise such as Kerr effect and Rayleigh scattering in the optical path of the FOG. The flatness of the output spectrum of the ASE light source also affects the scale of the FOG. In this paper, the influence of broadband fiber light source on the bias performance and scaling performance of HPFOG is analyzed theoretically, and the design of a high-flatness C+L band broadband ASE light source is developed. By analyzing the conditions of the output spectrum of the ASE light source from the C-band to the L-band until the C+L band is formed, the pump light power and the length of the erbium-doped fiber are optimized, and the output spectral width, power and spectral flatness of the ASE light source are simultaneously improved. Performance, the developed C+L band broad-spectrum ASE light source has a spectral width of 80nm and a flatness of less than 1.5dB. Subsequently, this paper compares the performance of HPFOG using traditional Gaussian ASE light sources and high-flatness C+L band light sources. The experimental results show that although the spectral symmetry of the C+L band broad ASE light source is weaker than that of the Gaussian spectrum ASE light source, but the scale factor performance of HPFOG is similar, and there is no obvious impact. The key is that the use of high-flat C+L band broad ASE light source significantly improves the bias stability of HPFOG. The normalized index shows that the 100s bias stability is improved by 30%.
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