| Optical module is an essential part of a modern fiber-optic communication networks.it has a great demand in the market.The competition between manufactures is also very intense.Reducing the cost of production test is the most important problem now. Nowadays, test of optical module is divided into two kinds of manual test and automated test.The manual test is very inefficient and costs too much time.The automatic test can reduce manual operations and test time,but it also need to replace the optical module from time to time.In a word,it also waste some time.To solve this problem,this paper proposes a new solution—Dual-channel test system.When the optical module is testing in one channel,we can replace the module in the other channel.So,the system always works in the test mode.It can improve the efficiency of the test greatly.In this paper,there are two issues:the design of two-channel test program and the processing of channel switching. In the stage of launching test, light of two optical modules can be sent to the oscilloscope through the 1 × 2 splitter. In the stage of receiving test,the system combine USB communication board, calibration source board and the light switch board effectively.Then,the system achieve the target of testing the reception calibration, sensitivity, forward warning and inverting alarm automatically without adjusting optical attenuator by people. In the stage of final test,the launching test and the receiving test can be completed within the same optical structure by switching the optical path. The processing of channel switching include power switching,I2 C switching and processing of the differential signal switching.Based on the issues above,the working contents in this paper are as follows:(1) the paper designs a dual-channel optical module testing program, including launching tset, receiving test and the final test program, which focusing on the optical design and test methods;(2) according to the dual-channel test board, the paper design the control circuit, the channel switching circuit, the current collecting circuit and the communication circuit;(3) according to the theory of signal integrity, the paper carrys out the impedance simulation of the differential pair and single-ended differential signal.Then,it gives the routing techniques of the differential signal.Considering of the design requirement of dual-channel test system and various parts of the circuit modules,this paper perform the overall functional test and key functions of the dual-channel test system.It contains of signal integrity verification,dual-channel test differences validations and application testing in the testing lines.By testing and verificating,we prove the dual-channel test system is stable and reliable,and its function can meet the design requirements. |
