Abstract

Progress has been made on an integrated acoustooptic modulator needed for a proposed optical communication network. The system, which is described elsewhere,¹ can employ a standing wave surface acoustic wave (SWSAW) to generate microwave subcarriers needed to multiplex analog and/or digital signals. Previous experiments demonstrated intensity modulation of a guided optical beam at a frequency of 70 MHz by a SWSAW which diffracted light in the Raman-Nath regime.^1,2 Intensity modulation of an optical beam at 600 MHz has been observed recently using a Bragg version of this modulator. Superimposing NTSC VHF TV signals on the bias current of the laser diode resulted in mixing between the TV signals and the 600-MHz acoustooptic modulation. Hence, the VHF TV signals were optically upconverted into the UHF range by the acoustooptic modulator. A photodiode was used to convert the UHF signals back into an electrical form. The carrier-to-noise ratio (CNR) was at least 30 dB for the picture carriers of the upconverted TV signals. The observed picture quality was good.

© 1989 Optical Society of America