An integrated circuit microcontroller for use in an optical transmitter that generates a modulated optical signal for transmission over dispersive fiber optic links in which a broadband radio frequency signal input is applied to first and second RF inputs of an external modulator for modulating the output of a semiconductor laser. The single integrated circuit is a digital signal processor that performs analog to digital conversion, digital processing, and digital to analog conversion, for producing an analog signals coupled to the input of the modulator, the circuit independently adjusts the DC bias of the first and second RF inputs to control a characteristic of the optical signal, such as noise associated with composite second order (CSO) distortion as a remote receiver.