HFAN-02.2.1: Maintaining the Extinction Ratio of Optical Transmitters Using K-Factor Control


This application note presents a new solution to maintaining constant optical output for laser diodes addressing high-speed, fiber-optic transmitter application. The solution involves using K-factor compensation to maintain laser extinction ratio by changing the modulation current in proportion to the bias current when closing the APC loop. The concept is discussed and experimental results are presented. This approach has been implemented in the MAX3863 2.7Gbps laser driver with modulation compensation.