Development of Digital Drive Power for Communication Laser Diode open site


Date: Dec 5, 2014

The emergence of the LD gave birth to the optical communication, and WDM promoted the development of the optical communication again. By many ways of the LD to unite as one light source, transmits multiple information channels on one of the optical fiber. Therefore, it is necessary to design one digital drive power for LD, including constant value unit and monitoring system. Constant value unit can ensure the stability of the wavelength and power, which directly affects the accuracy of information transmission. Monitoring system manages many of the constant value units uniformly.According to the curve of the LD power-current characteristic, Combined with the principle of the power and the wavelength modulation, this paper chooses the method of power-current and wavelength-temperature modulation, and starts on the development of the digital drive power for LD to realize the function of the system. The design of the constant value unit accords to the negative feedback control theory, including power and temperature. Because the method of the temperature-wavelength modulation slowly, this paper uses the PI isolated circuit to speed up the rate of the temperature modulation effectively. In addition, D/A, A/D and some digital I/Os expand on the constant value unit, which is used to connect the monitoring system. The monitoring system uses USB2.0 for high speed transmission, constructs digital control unit by combination of DSP and FPGA, and uses PC as the monitoring platform, which manages each LD through digital I/O flexibly.In addition, this system designs local/remote patterns. Constant value unit designs in the cabinet for the convenience of its independent work in local pattern. In remote pattern, two or more sets of cabinet can connect to monitoring system, managed by PC uniformly.At last, the system realizes the efficient modulation in power and wavelength, realizes data acquisition synchronously for real-time monitoring each laser status, and confirms LD power and temperature has upper stability, etc. The experiment shows that in 1h the stability reaches±0.015W in power, and±0.01℃in temperature.

Application: Telecom