HI Damian,
I have not link of this article.but I can write down text in here.
“The Continuous wave is 4APSK modulated by a DPMZM, in particular, the two sub-modulators of the DPMZM are biased at null point and driven by 10Gbit/s Data1 and Data2, respectively, to generate two BPSK signals with unequal amplitudes.The two BPSK signals are then constructively added by adjusting Bias-C such that a 4APSK signal can be obtained”
Can it help you make built modulator? I’m still trying to it in 1026edit.osd file. but not succeeded.