Taiwan has been known as the leader in the global industrial production line of semiconductor processing, where its mature supply chain in semiconductor manufacture industry has already realized the different levels of relevant technologies and applications. In the last decade, the invention of Si photonics has led to the advancement of photonics integration circuit by using semiconductor manufacture production line, allowing the advantages of multi-functional and cost-effective optical signal processing techniques, such as broadband, high resolution, low power consumption and low EM interference, to be built inside a small chip.
In the light of such technology trend, MOST of Taiwan has promoted the special topics project, named as Si photonics project, in 2018 in order to fulfill the future technology development in the future. Si photonic fiber gyroscope is one of the funded projects, which was led by Prof. Yi-jen Chiu in Department of Photonics, National Sun Yat-sen University. The team uses several new designs of optical and electrical circuits in silicon photonic integration chip, not only reducing the overall size of chip but also setting up a new level of angular velocity sensing capability. A tactical level of sensing capability (Bias instability = 0.158 deg/hr) has been demonstrated through employing such silicon photonic gyro chip. The integration of optical elements in chip has approximately decreased the cost by one third of the conventional interferometer fiber optical gyroscope. To be noted that, the design of Si photonic gyro chip could not only level up the gyro function but also bring new and multiple functions in a chip. For example, more functions except the conventional gyro elements are able to install in an mm-scale chip, enabling sensing and configuring capability. The unmanned vehicle and aerial camera with such light sensing tool can be made with stabilizer. In addition, the Si photonics gyroscope also has lots of potential for consumer purposes, such as bio engineering, autonomous cars, robot, navigation, and CubeSat.
Interferometric fiber optical gyroscope (IFOG) is one of indispensable components for sensing angular velocity in medium- and high- end navigation systems, such as aerospace, military, underwater and unmanned vehicles. In comparison to other types of gyroscope. Ring laser gyroscope (RLG) and hemispherical resonant gyroscope (HRG) are the most stable and highest resolution one up to the records now, however, the complicated structure need delicate assembly engineering, resulting in high cost. On the other hand, microelectromechanical system (MEMS) gyroscope fabricated in semiconductor foundry can be adapted to mass production line, thus leading to lowest cost per piece. Nevertheless, the mechanical properties render it to be low precision from up-to-date technologies. In the view point of gyroscope performance, IFOG could vary from high- end modules to medium- end ones, depending on the design and its related assembly technologies. With the promotion of Si photonic technologies, photonics integration offers an excellent solution for future gyroscope and related technologies.
The team of Si photonic gyroscope in the Department of Photonics at NSYSU has been funded by MOST for 4 years. In this project, the principle investigator (PI) was Professor Yi-Jen Chiu, the former Chair of the Department of Photonics, who was also responsible for developing broadband light source of gyroscope. The recruited co-host PI, Dr. Jen-Yang Liu, an expert in fiber-optic gyroscope. Prof. Yung-Jr Hung is also a co-host PI, a Si photonic expert. Base on Si photonic technology, several industrial partners have been tied within the project, forming a collaboration link. To develop gyroscope package and its driving circuit, Professor Chua-Chin Wang of the Department of Electrical Engineering, NSYSU, an integrated circuit (IC) expert, was also invited to develop closed-loop electronic circuit chips. The silicon photonic gyroscopic chips were jointly designed, developed, and characterized by professors Chin-Ping Yu, Tsung-Hsien Lin, Yung-Jr Hung, and Chun-Ta Wang of the Department of Photonics; the research on low-loss optical waveguide coils was led by Professor Chao-Kuei Lee and Professor Chun-Ta Wang; To improve the signal-to-noise ratio in optical signal processing, the noise-reduction technology in optical waveguide was led by Professor Chia-Chien Wei. Upon the past three year, excellent research work and Si photonic IFOG submodule have been attained, including the patents, top international conference and journal paper publication.