Fiber-Optic Transmission Of Microwave 8 Phase-PSK Signal

Transmission of a 6 GHz, 8-phase phase-shift-keyed (8Φ-PSK) signal over a 12.5 km single-mode fiber in the 1.3 μm wavelength region with a 5 dB power margin was demonstrated for the first time. A digital modem operating at 26 Msymbol/s (78 Mbit/s), a high speed' multimode InGaAsP laser diode, and a high speed PIN diode were used in this fiber-optic transmission system. Floor characteristics and a power penalty observed in the system bit error rate performance were found to be caused by the intensity noise of the laser diode, particularly the reflection-induced intensity noise.