Abstract

Optical microwave links are becoming increasingly interesting for applications in microwave systems in which conventional transmission techniques are difficult to use. Examples of such systems are optical subcarrier systems,¹ synchronously distributed microwave systems such as mobile telecommunication networks, and the remoting of antenna stations. Here we demonstrate that a two-electrode semiconductor optical amplifier (SOA) can be used as a highly efficient quadrature-phase-shiftkeying (QPSK) modulator in the transmitter unit of such links. Together with offset phase-locked semiconductor distributed- feedback (DFB) lasers, the SOA modulator provides a complete transmitter unit based solely on semiconductor devices that can be operated at high carrier frequencies and, further, has the potential of monolithic integration.

© 1994 Optical Society of America