Analog performance of an all-optical frequency upconverter utilizing an electro-absorption modulator for radio-over-fiber applications

An all-optical frequency upconverter utilizing an electro-absorption modulator (EAM) has been experimentally demonstrated for radio-over-fiber applications. An optical radio frequency (RF) signal having the RF frequencies of 19.5 and 28.5 GHz was generated by mixing an optical intermediate frequency (IF) signal having the IF frequency of 4.5 GHz with an electrical local oscillator (LO) signal in the EAM. Dependence of modulation characteristics of the all-optical frequency upconverter on the bias voltage of the EAM were investigated to find out optimum operating condition. The all-optical frequency upconverter showed the phase noise of approximately -92 dBc/Hz at 1 kHz offset frequency, indicating that there existed negligible degradation of phase noise during upconversion process.