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Resonator micro optic gyro (RMOG) is a promising candidate for applications requiring small, light and robust gyros. In optical passive ring resonator gyros, clockwise and counter clockwise lightwaves are modulated at different frequencies to reduce the backscattering induced noise. The effectiveness of this technique, however, is determined by the carrier suppression level. Accurate modulation index and high environmental temperature stability is required for achieving high total carrier suppression for the traditional single phase modulation technique (SPMT). In this paper, we propose an RMOG based on the double phase modulation technique (DPMT). Compared with the traditional SPMT, two additional phase modulations are added to provide additional carrier suppression. It is found that the control accuracy of the modulation index and temperature stability is relaxed more than 30 times. It is easily performed for reducing the backscattering error below the shot noise limited sensitivity. The modulation parameters in the DPMT are analyzed and optimized. Based on the optimum parameters of the DPMT, a bias stability of 1.85×10⁻⁴ rad/s is successfully demonstrated in the polarization maintaining silica waveguide resonator with the length of 7.9 cm. This is the best result reported to date, to the best of our knowledge, for a waveguide type passive ring resonator gyro.

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Summary: An ultrasonic irradiation assisted polymerization method has been used to prepare PANI nanotubes and nanofibers by using different doping concentrations of mineral or organic acids. It has been found that PANI nanotubes can be produced when the concentration of the dopant acid is low. However, PANI nanofibers can also be produced when the concentration of the dopant acid is high. For nanotubes synthesized at a low concentration of the dopant acid, the outer average diameter can be changed from about 150 nm using phosphoric acid to 200 nm using nitric acid as the dopant and the inter diameter is in the range of 10–50 nm. For nanofibers, the diameter ranges from about 50 nm using nitric acid to more than 110 nm using perchloric acid as the dopant. The mechanism of the formation of the nanotubes and nanofibers may be due to the formation of different kinds of micelles and the prevention of the second growth of the PANI by ultrasonic irradiation. The chemical structure of the PANI nanotubes and nanofibers are characterized by FTIR and UV‐vis absorption spectra and XRD patterns. The conductivity of the PANI nanofibers is comparable to that of conventional PANI samples.TEM images of PANI nanofibers synthesized under ultrasonic irradiation doped by perchloric acid.magnified imageTEM images of PANI nanofibers synthesized under ultrasonic irradiation doped by perchloric acid.