Research on drive and control technology of external modulated DFB laser diode

We attempt to study external modulation characteristics in 1550 nm microwave over fiber links which overcome the disadvantages of light spectrum expansion and unstable optical extinction ratio because of direct modulation. The relation property between output power, threshold current and temperature is discussed at first based on physical model of a multiple quantum well-distributed feedback (MQW-DFB) laser diode (LD). This paper focuses on the corresponding power and temperature control circuits which are set up to make the optical power changing within 0.5% and temperature control precision better than 0.3degC. Experimental results show that external modulation light emitting module composed by the 1550 nm MQW-DFB laser diode and corresponding driving circuits can effectively improve output light power stability. As an application, we realize 10 GHz microwave transmission over fiber links with high linearity and low distortion.