1) The working wavelength is located in the low-loss window of the fiber;
2) Wide spectral width to reduce parasitic interference caused by back-reflection, coherent back-scattering and nonlinear optical Kerr effect;
3) Higher and stable output optical power of pigtail fiber, and interference signal with higher signal-to-noise ratio has been obtained;
4) Stable average wavelength to achieve the stability of the scale factor;
5) Approximate Gaussian smooth spectrum to reduce spurious interference;
6) Appropriate degree of polarization. For fiber optic gyroscopes using polarization-maintaining fiber couplers, a higher polarization degree is conducive to the full utilization of optical power. For fiber optic gyroscopes using single-mode fiber couplers, a lower degree of polarization is conducive to input The polarization and power of the optical signal are stable.
The light source of the fiber optic gyroscope is a broadband light source, and the average wavelength stability is required to be high, so the entire spectrum is required to be relatively stable, which is the main difference from the optical communication light source. Optical communication generally requires the light source to have a narrow linewidth, and the wavelength stability requirements mainly focus on the center wavelength, which is relatively low.
The main parameters of the light source affecting the performance of the fiber optic gyroscope are the output optical power, spectral width, average wavelength, spectral symmetry and modulation degree. There are two main light sources used in fiber optic gyroscopes, superluminescent light-emitting diode (SLD) light sources and erbium-doped fiber light sources.
SLD light source is a semiconductor light source in which spontaneous photon emission is amplified by one-way excitation, with high output power, narrow beam divergence angle, and wide output spectrum (low temporal coherence). SLD mainly has two bands of 830nm and 1310nm. Since the average wavelength stability and power do not meet the high-precision requirements, it is suitable for medium-precision fiber optic gyroscopes.
The working wavelength of the erbium-doped fiber light source is 1550nm. Due to its high power, good average wavelength stability and large size, it is mainly used for high-precision fiber optic gyroscopes. In optical communication, erbium-doped fiber light sources are generally not used, but erbium-doped fiber amplifiers with similar technology are used, which are subjected to relatively loose mechanical and temperature environments.
