Hi Vishal,
I think the bandwidth of the modulated signal depends on the modulating signal filtering bandwidth.
in the attached example, you can see the difference in the modulated signal after the LiNb Mach-Zehnder modulator at two different values of the input low pass Filter such as 0.2 * Bit rate and 0.9 * Bit rate for example.
if you open the help file of this component, you can see its references:
References:
[1] Cartledge, J. C., Rolland, C., Lemerle, S., and Solheim, A., “Theoretical performance of 10 Gb/s lightwave systems using a III-V semiconductor Mach-Zehnder modulator.”, IEEE Phot. Techn. Letters., 6, 282-284, (1994).
[2] Cartledge, J.C., “Performance of 10 Gb/s lightwave systems based on lithium niobate Mach-Zehnder modulators with asymmetric Y-branch waveguides”. IEEE Phot. Techn. Letters., 7, 1090 -1092, (1995).
Hope that helps,
thanks
Mohamed