Free-Space Integrated Photodetector With Reduced Phase Tracking Error

摘要

A Mach-Zehnder (MZ) interferometer modulator structure for fiberoptic telecommunications is disclosed in which drift of the operating point can be monitored with a reduced phase tracking error. One or more components of free-space light radiated into the substrate of the MZ modulator are selectively detected with one or more photodetectors. Suitable summing circuits are described for nulling out undesired photocurrent contributions in the photodetector(s) from on-state and off-state light radiated from the MZ.