NEW INTERFEROMETRIC FIBEROPTIC GYROSCOPE WITH AMPLIFIED OPTICAL FEEDBACK

A novel interferometric fiber-optic gyroscope with amplified optical f eedback by an Er-doped fiber amplifier (EDFA) is proposed and theoreti cally investigated (the proposed gyroscope is named the feedback EDFA- FOG, FE-FOG in what follows). The FE-FOG functions like a resonant fib er-optic gyro (R-FOG) because of its multiple utilization of the Sagna c loop; however, it is completely different because a low-coherence li ght source is used. In addition, the gyro output signal is pulsed beca use the modulation frequency of the phase modulator placed in the Sagn ac loop is selected to match the total round-trip time delay of the li ght, which includes the Sagnac-loop delay plus that of the feedback lo op of the fiber amplifier. The sharpness of the output pulse can be ad justed by both the gain of an EDFA and the modulation depth of the pha se modulator. When rotation occurs the peak position of the output pul se is shifted as a result of the Sagnac effect. The resolution of the rotation measurement depends on the sharpness of the output pulse. The techniques of both the open-loop and closed-loop methods are describe d in detail, which shows the great advantage of the proposed gyroscope over the to the conventional interferometric fiber-optical gyroscope (I-FOG).