Stable Multi-Wavelength Fiber Lasers for High-Precision Fiber-Optic Gyroscopes

We report an innovative fiber-optic gyroscope (FOG) employing a broadened multi-wavelength fiber laser (MWFL) to improve its noise, drift, and scale-factor stability. The MWFL consists of two offset chirped gratings inscribed in a polarizationmaintaining Er/Yb-codoped fiber. It was pumped at 976 nm and spectrally broadened by an electro-optic modulator driven by broadband noise. Two MWFLs with different grating lengths were tested, the shorter one emitting 17 wavelengths and the longer one emitting 38 wavelengths, with a measured mean-wavelength stability as low as 1.3 ppm and 3.05 ppm, respectively. A 3-km FOG interrogated with the 17-wavelength laser exhibited a noise of 500 μdeg/√h and a drift of 3.2 mdeg/h, while with the 38- wavelength laser it had a noise of 420 μdeg/√h and a drift of only 2.5 mdeg/h. In comparison, the same FOG interrogated with an Er-doped superfluorescent fiber source with a 3-dB bandwidth of 17 nm had a noise of 500 μdeg/√h and a drift of 2.1 mdeg/h. This is the first time, to our knowledge, that a laser-driven FOG has achieved a drift as low as that of a broadband-source-driven FOG. This approach can be extended to other multi-wavelength lasers, potentially driving innovation in ultra-low noise and ultra-high precision gyroscopes.