Third-order intermodulation distortion in an optical downconverter

The first two-tone measurements of third-order intermodulation in a wide-band (1-18 GHz) optical downconverter utilizing cascaded Mach-Zehnder modulators are presented. Intermodulation originates in the RF modulator and is downconverted along with the fundamentals to intermediate frequencies (IF). The third-order intercept in the IF band is measured and agrees well with theory.