Design And Research Of Gaussian-shaped Spectrum Erbium-doped Fiber Source

As a kind of fiber-optic sensor,fiber optic gyroscope(FOG)has developed into a new mainstream instrument with epoch-making characteristics in the field of inertial technology.As the optical signal source,the performance of light source directly affects the measurement accuracy of FOG.At present,high-precision FOGs generally adopt the 1550 nm band erbium-doped fiber(EDF)sources as their light sources.However,the natural fluorescence spectrum of the EDF exhibits a "double hump" structure in the C-band,which limits the further improvement of the accuracy.Therefore,the output spectrum of the EDF should be shaped when making a source.Compared with the commonly used flat spectrum EDF source,the spectral symmetry of the Gaussian-shaped spectrum source is better,and the environmental temperature variation and pump power fluctuation affect its spectral stability less.Meanwhile,the self-coherence is lower and coherence length is shorter as for the Gaussian-shaped spectrum light source,which can effectively reduce the phase errors of the FOG.Hence,the Gaussian-shaped spectrum EDF source is more suitably applied in the high-precision FOG.In this work,the interferometric fiber optic gyroscope(IFOG)was selected as the applied object,and the related researches on Gaussian-shaped spectrum EDF source were carried out.The main contents are as followed.First of all,based on the basic theory of the EDF source,with analyzing the typical structures and pump methods of the source,a two-stage single-pump source structure was designed.The main influencing factors on spectral adjustment were studied by OptiSystem software simulation.According to the control principle of the pump laser diode,the drive and control circuit scheme of the EDF source was designed and the circuits were debugged.Secondly,according to the conclusions of the previous simulation,through optimizing the lengths of the two-stage EDFs,a Gaussian-shaped spectrum EDF source with an output power of 9.8 mw,a spectral width of 10.6 nm and an average wavelength of 1560.2 nm was obtained.On the basis,the source were tested under normal temperature and variable temperature conditions,respectively.The results show that the designed source meets the design requirements of high-precision FOGs.Finally,a test prototype was assembled with the designed Gaussian-shaped spectrum EDF source and a three-axis integrated FOG.The static test with normal temperature and the scale factor stability test with variable temperature were carried out,respectively.Compared to the test result of a FOG prototype using a flat spectrum source,the Gaussian-shaped spectrum source can improve the stability of the scale factor of the gyroscope.