Performance degradation of integrated optical modulators due to electrical crosstalk

In this paper, we investigate electrical crosstalk in integrated Mach-Zehnder modulator arrays based on n-doped InP substrate and show that it can be the cause for transmitter performance degradations. In particular, a common ground return path between adjacent modulators can cause high coupling noise up to -20 dB which leads to system power penalties of more than 10 dB at 10 Gb/s OOK modulation. Furthermore, we demonstrate that electrical crosstalk is significantly reduced in the absence of the shared ground and that it varies with modulator separation distance. Experimental results are shown that indicate a crosstalk tolerance of -40 dB for 1 dB power penalty at 10 Gb/s.