Silicon photonic integrated circuit with electrostatic discharge protection

A photonic integrated circuit (PIC), the PIC comprising:

• a first optical coupler;
• a second optical coupler;
• a polarizing beam rotator-splitter (PBRS) having a PBRS input, a first PBRS output and a second PBRS output, the first optical coupler optically connected to the polarization rotator-splitter via the PBRS input;
• a beam splitter (BS) having a BS input, a first BS output and a second BS output, the second optical coupler optically connected to the BS via the BS input;
• a first directional coupler (DC) having a first DC input, a first through output and a first cross output, the first DC input optically connected to the first PBRS output;
• a second DC having a second DC input, a second through output and a second cross output, the second DC input optically connected to the second PBRS output;
• a first variable optical attenuator (VOA) having a first VOA input and a first VOA output, the first VOA input optically connected to the first through output;
• a second VOA having a second VOA input and a second VOA output, the second VOA input optically connected to the second through output;
• a first monitor photodiode optically connected to the first cross output;
• a second monitor photodiode optically connected to the second cross output;
• a first 90-degree hybrid mixer (HM) having two first HM inputs and four first HM outputs, the two first HM inputs optically connected to the first VOA output and the first BS output, respectively;
• a second 90-degree HM having two second HM inputs and four second HM outputs, the two second HM inputs optically connected to the second VOA output and the second BS output, respectively;
• a first quad-channel waveguide photodiode (WGPD) array having four first WGPDs, each of the four first WGPDs optically connected to a respective one of the four first HM outputs and capable of obtaining a respective one of predefined beat phase offsets of 0 degrees, 180 degrees, 90 degrees and −90 degrees generated by the first 90-degree HM based on the first VOA output and the first BS output;
• a second quad-channel WGPD array having four second WGPDs, each of the four second WGPDs optically connected to a respective one of the four second HM outputs and capable of obtaining a respective one of predefined beat phase offsets of 0 degrees, 180 degrees, 90 degrees and −90 degrees generated by the second 90-degree HM based on the second VOA output and the second BS output;
• and
• an eight-channel bias circuit array having eight integrated bias circuits, each of the eight integrated bias circuits comprising a respective one of the four first WGPDs and the four second WGPDs.