Research And Design On Tunable Laser Module

In the optical communication network, tunable semiconductor laser is the ideal light source for wavelength division multiplexing(WDM) system. Compared with traditional semiconductor laser, tunable semiconductor laser can output different kinds of wavelengths, is enble to dynamically select certain wavelength according to specified requirement. It also has the advantages of flexibility, versatility, economy etc.. Costs of devices in the optical communication network system is greatly reduced by using the tunable semiconductor laser.Therefore the application of tunable laser has broad prospects in the field of optical communication. However, fabrication of common commercial tunable lasers is very complicated by using traditional process technology,and the yield of lasers is very low.High production costs lead to the inability to mass production. Reconstruction equivalent chirp(REC) technique is an effective way to solve this problem. In this paper, the laser array based on REC technology is used as the light source device. We study the system design of the light source module of the REC laser array.In this paper, the driving circuit and control software are designed for the device characteristics of the REC laser array, and the combination of the erbium doped fiber amplifier and the photoelectric detector. A design scheme of output stable tunable laser module is presented. The system is mainly divided into hardware circuit and software part. In hardware circuit, STM32F103VET6 is chosen as the control chip of the hardware circuit, to control each module of the drive circuit. Multi channel current drive of REC laser array is realized by using Max5110 chip. The high current drive demand of the pump laser is satisfied by the negative feedback analog circuit. A temperature control circuit based on Max8521 chip is designed. Through the optical receiving circuit, the output feedback of the light source is collected. External OLED display screen is used to realize the visual display of information.In the software part, the upper computer software provides the user with the driving control and data display interface. Through the RS-232 serial communication, the host computer commands to the control chip. The lower computer program based on embedded system is the underlying driver of the module circuit. According to the feedback, the lower computer program PID to regulate the output light power.It is demonstrated by experimental results that driving current and working temperature of laser module can be accurately controlled by the designed software. Wavelength of laser module is capable to be precisely controlled and continuously tuned in a certain range.Besides, EDFA amplification effect is good. By using the designed software and circuit, the laser module can be precisely controlled to ourtput a high performance, stable light signal.