High-performance InGaAsP-InP multiple-quantum-well traveling-wave electroabsorption modulators (EAMs) have been developed for analog optical links. A high slope efficiency of >4N at 1.55 mum for a 300-mum-long EAM is measured. A detailed study of the nonlinearity and the spurious-free dynamic range (SFDR) is presented. By optimizing the bias voltage and the input optical power, the SFDR can be improved by 10-30 dB.