Implement control algorithm to wavelength tracking system of laser diode

• Main Authors: Ping-Che Lee, 李秉哲
• Other Authors: San-Liang Lee
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/2b79c6

碩士 === 國立臺灣大學 === 電子工程學研究所 === 106 === Integrated optical circuit is used the advantage of transmit optical signal to increase the data transmission, bandwidth and improving the performance of integrated circuit, which resolving the limitation of transmission in integrated circuit, hence integrated optical circuit is able to be adaptable in cloud computing and application of the big data. However, if we use the laser diode as the light sourse, it will easily be influenced by ambient temperature and error in the process. On this account, finding a way to make the laser source to be more stabilize is the emphasis of modify the integrated optical circuit. The purpose of this thesis is designing and developing a wavelength tracking system for temperature sensitive semiconductor device, e.g. laser diode. To be more specific, there are two parts of the structure that fulfilling this research:optical path structure and circuit structure. First of all, we use a laser diode, which provide 1550 nm of scattering DFB laser (Distributed Feedback Laser) as light sourse, then setting a FBG(Fiber Bragg Grating) with the maximum that reflectance is nearby 1550nm.In addition to FBG is used to filter, the tracking system is set to tracking wavelength of the maximum value in reflective end. Afterward, we set a photodector as interface conversion make optical signal transform to electrical signal for the next part. The part of circuit is composed by TIA(Transimpedance amplifier), digital signal processor and two-way circuit. In the digital signal processor, two-way control algorithm proposed in this thesis is used as the wavelength tracking strategy, which output PWM(pulse width modulation) signal to two-way circuit for wavelength tracking. In addition, the algorithm can detect changes in the external ambient temperature during wavelength tracking. Finally, this paper established a wavelength tracking system and using the digital signal processor (Arduino UNO) as the controller. Experimental results demonstrate the validity of the proposed system architecture and the feasibility of the algorithm.