Abstract
This paper presents a simple method for compensating the Sagnac phase shift in an interferometric fiber-optic gyroscope (I-FOG) with a piezoelectric modulator. The common advantages of I-FOGs with closed-loop compensation are linearized output characteristics and insensitivity to the light source power, including its time and thermal-induced fluctuations. Whereas closed-loop operation is normally achieved via ramp modulation requiring an electro-optic modulator, all-fiber architectures with a piezoelectric modulator are mostly limited to open loop. Nevertheless, such setups can more conveniently utilize a less expensive single-mode fiber with depolarized light and do not require any custom-made components. The proposed method allows us to combine the advantages of both approaches. Closed-loop compensation is ensured by adding further sinusoidal modulation to the common biasing modulation, such that the Sagnac phase shift is compensated solely at the sampling instants. We describe and experimentally demonstrate the proposed approach, utilizing a test setup to compare our closed-loop solution with open-loop operation. The results denote that the method provides a cost-efficient manner of performance improvement compared to the open-loop I-FOGs based on a piezoelectric modulator.
Highlights
Using gyroscopes to sense angular motion with respect to the inertial frame is presently essential for many applications, including inertial navigation, attitude and heading reference systems (AHRS), and industry
Assuming the suppression of nonreciprocal effects, such as polarization nonreciprocity and the Faraday or Kerr effects [20], the phase shift ∆φ is equal to the Sagnac phase shift, ∆φs = KΩ, where Ω is the angular velocity and K represents the constant of the interferometric fiber-optic gyroscope (I-FOG) given by its dimensions and used wavelength
To demonstrate the advantages of the proposed compensation technique, we performed several tests of the I-FOG setup operating in both the open-loop and the closed-loop modes
Summary
Using gyroscopes to sense angular motion with respect to the inertial frame is presently essential for many applications, including inertial navigation, attitude and heading reference systems (AHRS), and industry. Gyroscopes are part of inertial measurement units providing information about the position in a space without any external reference. These systems are widely used in aeronautics, submarines, drilling and mining, spacecraft, satellites, and vehicles such as cars or mobile robots [1,2]. Only ring laser gyroscopes (RLGs) and interferometric fiber-optic gyroscopes (I-FOGs) facilitate commercial use. The former have been a leading technology for decades, despite being limited by the lifetime of the He-Ne tube, more difficult construction, and the need of frequency dithering [2,3].
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