Adaptive predistortion of lasers using multivariable feedback algorithm

An adaptive predistortion technique for direct modulated lasers is proposed and experimentally demonstrated. The predistortion calibration is through multivariable feedback control and does not require digital signal processing or storing data in memories. Therefore, this technique suggests a potential analogue implementation with less circuit complexity. A design example is implemented using standard CMOS technology. Experimental results confirm the validity and the robustness of the feedback algorithm. Measured results show about 5-15-dB reduction of IM3 and HD2 distortion over more than 300-MHz bandwidth.