Patent ID: 9628186
Date: 2017-04-18
CPC Classifications: H04B

Claim:
1. An optical modulator comprising: a Mach-Zehnder interferometer (MZI) structure including a tunable splitter arranged to split input light into two modulator arms of the MZI; a polarization combiner arranged to combine light from the two modulator arms into an output signal, wherein the two modulator arms connect the tunable splitter to the polarization combiner; an on-off keying (OOK) modulator positioned in a first arm of the two modulator arms; and a single-polarization, four-level, pulse-amplitude (PAM-4) modulator and a polarization rotator positioned in a second arm of the two modulator arms, wherein the tunable splitter is configured such that 4/7 of the input light is directed into the first arm and 3/7 of the input light is directed into the second arm for modulating the input light according to eight-level pulse-amplitude modulation (PAM-8) format.