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.