A plurality of optical communications systems including a SPW modulator are described. The communications systems include an
optical transmitter coupled to an
optical fiber communications link which carries a optically modulated information
signal to an optical
receiver. The
laser transmitter includes a
laser light source which is optically coupled to a SPW modulator which has been particularly adapted for
broadband communications by selecting its transfer characteristic and modulation structure. A
broadband signal containing a plurality of information channels, for example CATV channels, is applied to it modulator electrodes. The modulation
signal varies the
power coupling between the guided
laser light source signal and a SPW in the modulator. The result is an intensity modulated optical signal that is output to the
optical fiber for transmission to the optical
receiver of the
system. Alternatively, the
communications system includes a high power laser coupled to an optical splitter to divide its output power in two or more optical source outputs. Each optical source output is then used to drive an associated SPW modulator. Each of the modulators receives a
broadband signal with which to modulate its optical source. After modulation, the modulated lightwave from a modulator is coupled to a corresponding
optical fiber for
carriage to an optical
receiver. In this manner, several broadband information signals can be communicated over the
system using only one
laser source. A net benefit from using one
higher power laser, rather than several lower power ones, is one of cost, purity and similarity of the several signals. This configuration is enhanced by the lower loss and higher
linearity of the SPW modulators. Further, several WDM embodiments including those having serially cascaded SPW modulators are provided. The transfer characteristic of the SPW modulators are tailored to either be more efficient for an analog or a digital modulation signal by adding or subtracting
grating effects.