The Design And Implementation Of An Integrated Optical Sub-Assembly Test System

The Optical Sub-Assembly (OSA)is the base and important device of the optical fiber communication system. Traditionally, in the testing process of the OSA parameters, the use of a large number of instruments and complex circuit connection, using a PC or even a manual way to control the instrument and to collect various kinds of information, so that, the test system is expensive, complicated, occupying a large area, and a lot of trouble of the maintenance, of cause, the test system is not suitable for large-scale use in the production line.The thesis is precisely to resolve the problem, use home-made instruments and embedded systems to design an integrated automatic test system of OSA. The main contents are as follows:1. An improved adjustable current source is used to design a laser driver circuit with hot-plug function; a large photosensitive area photodiode and a wide dynamic range logarithmic converter are used to design an optical power meter. A combination of both, form a LIV (light intensity-current-voltage) circuit of Transmitter Optical Sub-Assembly (TOSA).2. Analyze the principle of bit error test, useVSC8228chip to design a bit error tester; the rate can up to4.25Gbps, and it can replace the expensive BERT.3. Use the embedded core board to control home-made instruments, it can replace the PC and reduces the area occupied by the test system, so the cost of the test system is further reduced.4. According to the theory of high-speed circuit design, combined with practical experience in hardware engineering, design the PCB of the test board.5. Analyze the functions of ADuC7020microcontroller on the test board, select the event polling mode from common embedded software programming mode and improve the programming mode according to the actual situation, design a firmware for the test board.6. Analyze the process of Linux system porting, including the porting of U-Boot, Linux kernel, Linux driver, Busybox, root file system and Qt.7. Analyze the requests of the automatic test software and design it in accordance with the theories and methods of software engineering, including account management, OSA information management and the parameter data import, automatic testing of OSA and test data export, calibration management and programming ADuC7020in application programming functions.