Abstract

An optical communication system by which broadband analog and high speed digital information is transmitted simultaneously can be implemented using radio frequency (rf) or microwave subcarrier multiplexing (SCM). This system can also be used for general broadband communications if we can use subcarriers of tens of gigahertz.¹ Therefore we call this system MDM (microwave division multiplexing). However, because of the nonlinearity of laser modulation, serious intermodulation occurs especially in the high frequency range. Double-beam modulation (DBM) has been suggested and demonstrated using a standing wave acoustooptic modulator (SWAOM) to 1.2 GHz. Compared with intensity modulation, the DBM system induces less harmonic distortion and intermodulation. The DBM can be implemented in many forms.

© 1989 Optical Society of America