Hıgh Performance Mıoc (Multıfunctıonal Integrated Optıcal Chıp) Desıgn Fabrıcatıon And Characterızatıon For Fıber Optıc Gyroscope Applıcatıons
Özet
Laser-based fiber optic gyrometers (FOG) used in navigation systems have been developed for various applications since the 1970s. In this thesis, the working principle of FOG and the sub-components of the system are mentioned. The design, production and optimization studies of the waveguide-based multifunctional integrated optical device (MIOC), which is described as the heart of FOG, are included. The annealed proton exchange (APE) method has been developed for MIOC to show high performance in the system. First of all, straight waveguide fabrication was performed with the APE method, and the width of the waveguide to be integrated to the optical fiber was optimized. With the findings obtained, it was determined that the index change values required for connecting the 7µm wide waveguide to the optical fiber with the least loss (about 60% throughput) were in the range of 0.025-0.030. On the other hand, the importance of temperature and time factors in waveguide formation was investigated. Studies have been carried out that will allow the variations occurring in the first stage of the two-stage APE method to be compensated with the interventions made during the second stage. As a result of the efforts to optimize the design that will allow the MIOC device to split the light into two, it was concluded that a y-coupler design with a bending radius bigger than 4 cm could be selected, but considering the device size, packaging and other factors, the device design for the bending radius larger than 13 cm was decided. In order to carry out the APE process in hot acid safely and in multiples, a custom mechanism was designed and the fabrication was carried to mass production. Preliminary interventions were made during fabrication to eliminate the thermal instabilities that may occur between the MIOC and the optical fiber carrier, which has a different expansion coefficient than MIOC. During the temperature tests carried out in the temperature range of -40 °C – (+85) °C, it was measured that the optical power of the devices changed less than 0.5% and it was observed that the devices were stable against environmental factors. System level tests of fabricated MIOC devices were carried out, and PER values were measured at 49 dB. As a result, MIOC fabrication has been realized with the performance that will allow the external polarizer to be removed from the system. With the removal of the external polarizer from the system, space was saved in the whole FOG system, and with the design and optimization studies carried out during this thesis, the critical technological device supplied from abroad was developed with national resources.
