As a high-precision angular rate sensor, high-precision fiber optic gyroscope (HP-FOG) can be used for space positioning, strategic missile guidance and submarine navigation. With the further improvement of the demand for navigation accuracy under deep and open sea conditions and satellite rejection conditions, the goal is to manufacture FOG with higher accuracy and sensitivity. The noise of FOG has become the key to restrict its application in high-precision field. In this paper, the noise source of FOG is analyzed, and the method of using semiconductor optical amplifier to suppress relative intensity noise and feedback adjustment to reduce noise is given. In theory, we propose a scheme of FOG using three photon states as light source to improve the detection sensitivity. In theory, this scheme can realize three times super-resolution measurement.
With the increasing demand of navigation and positioning services, the accuracy and safety of traditional navigation system have been limiting factor of future application. The development of quantum technology brings hope to the research and development of a new generation of navigation system. In this paper, the application of quantum technologies in fiber optic gyroscope is introduced and analyzed.
With the change of working time and environmental conditions, the performance of optical fiber coil has deteriorated, which seriously affects its long-term stability. In recent years, the performance of fiber optic gyroscope(FOG) has been continuously improved, and the requirements for adhesive of fiber optical coil have become higher and higher. It is required not only to meet the stability of coil potting, but also to resist high and low temperature environment for a long time during operation of FOG. In view of this, the study in the environmental stress effects of optical fiber coil adhesive was carried out. Based on optical fiber coil, this paper introduces the environmental stress and its influence mechanism of polymer materials aging, and focuses on the optical fiber coil adhesive aging behavior, as well as analyses the physical and chemical properties of adhesive. On basis of this, environmental stress tests were carried out, and the physical and chemical properties of adhesive were obtained. The experiment and analysis results showed that the glass transition temperature will significant transfer under excessive ultraviolet exposure or a long time high temperature of 85degree Celsius and low temperature of -45degree Celsius, and the adhesive viscosity significantly increased in high humidity environment. Under the comprehensive effect of various environmental stress, the adhesive properties will changed and further affect the stability of optical fiber coil.
With the rapid development of the fiber optical gyroscope technology and its widely applies, the multi-axis Fiber Optical Gyroscope (FOG) such as the triaxial FOG and its system are popular more and more.[1-2] For the requirement of less weight and less size,[2] the multi-axis FOG needs higher electromagnetic structure design skills and more critical devices compared with uniaxial FOG. The Z axis of some triaxial FOGs occur the problem of the bias instability over tolerance, which is a real engineering case in our development process. In this paper experiments are carried out after the influence factors are analyzed. Results show that the modulation of the Z axis is interfered by the other two axes. There are three test steps in the experiment including the optical unit test, the modulator test and the modulator shield test with different materials. A simulation of the original shield structure is applied in order to find the structure defects. Two defects are found on the base of the analysis of the electromagnetic structure check. The main defect is that there is a hollow structure on the top of the Z axis in the system which causes extra electromagnetic circuit from the other two axes. The other defect is that each axis is exposed under complex circumstance with less modulator shield. The modulator with less shield has the merit of less thermal stress owing to the free contraction between the metal packaging and the modulator. In our triaxial FOG system, the modulator shield structure inherits from the uniaxial FOG with less shield, in order to decrease the thermal stress. As we know, in the uniaxal FOG the modulator will still robustly work under a clean electromagnetic circumstance, even there is no shield upon the modulator. However, in the multi-axis FOG there are obvious crosstalk interference between the different axes, when all axes are working together with a close frequency. Based on the experiments and the analysis, the following design principles are given. Firstly, the thermal factors, the vibration factors and the electromagnetic factors should be considered at the same time when the modulator shield is designed. Secondly, the Fe-Ni material has better shield effect than the common metal like Aluminum. Thirdly, there are two kinds of resins, the hard buffer and soft buffer, to connect the Y-junction fiber tail and the metal capsulation. This paper is of great use to the engineering of the multi-axis fiber optical gyroscopes and the fiber optical gyroscope system applications.
Based on the Sagnac effect, the small changes in thermally induced stresses and microcosmic size of optical fiber coil can cause the drift of the Shupe error and scale factor of fiber optic gyroscope (FOG). As polymer functional resin represents a high proportion in optical fiber coil, its physical and chemical properties determine largely the thermally induced stresses and dimensional stability of the coil, thus influencing the performance of FOG. Given the demands for the long-term stability and temperature characteristics of FOG, this paper studies the influence of molecular chain structure and thermal conductivity of polymer functional resin for optical fiber sensing on FOG. The experimental results suggest: high thermal conductivity can reduce the thermal induced stresses of polymer functional resin of reticular molecular structure, greatly improving the zero bias stability of FOG at all temperature; hyperbranched molecular structure reports outstanding creep-resistant characteristics thanks to the significantly reduced internal free volume of optical fiber coil after encapsulation and insignificant dimensional changes at all temperatures, thus ensuring long-term stability of the scale factor of FOG.
A compact all-photonic-crystal-fiber (all-PCF) polarizer based on fused-type mode-selective fiber coupler is proposed theoretically. Around the wavelength of 1550 nm, the injected unpolarized fundamental mode in the solid-core PCF was selectively coupled into one polarization-mode of polarization-maintained photonic crystal fiber (PMPCF) by welldefined fiber cladding reduction, pretapering and fusion. Numerical simulations indicate the polarization direction of the excited polarization-mode depends on the tapered diameters of solid-core PCF and PMPCF. Moreover, the operation bandwidth of the proposed polarizer is more than 400 nm, which can completely cover the bandwidth of the erbiumdoped solid-core PCF amplified spontaneous emission (ASE) light source. The all-PCF polarizer is anticipated to serve as the key element in the PCF optic gyroscope.
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