Optical system with offloaded optical components

A method comprising:

• receiving, at a first photonic integrated circuit, a first optical signal comprising a first mode and a second mode different from the first mode, and wherein the first photonic integrated circuit comprises a polarization splitter rotator, a first demultiplexer, and a second demultiplexer;
• separating, by the polarization splitter rotator, the first optical signal into a second optical signal with the first mode and a third optical signal with the first mode;
• separating, by the first demultiplexer, the second optical signal into a first plurality of optical signals;
• separating, by the second demultiplexer, the third optical signal into a second plurality of optical signals;
• and
• coupling the first plurality of optical signals and the second plurality of optical signals couple into a second photonic integrated circuit, wherein the first photonic integrated circuit is positioned on the second photonic integrated circuit.

An optical circuit comprising:

• a fiber array unit comprising:
• a polarization splitter rotator arranged to separate a first optical signal into a second optical signal with a first mode and a third optical signal with the first mode, wherein the first optical signal comprises the first mode and a second mode different from the first mode;
• a plurality of demultiplexers arranged to separate the second optical signal into a first plurality of optical signals and the third optical signal into a second plurality of optical signals;
• a photonic integrated circuit arranged to produce one or more electronic signals based on the first plurality of optical signals and the second plurality of optical signals from the fiber array unit, wherein the fiber array unit is positioned on the photonic integrated circuit;
• and
• an electronic integrated circuit positioned on the photonic integrated circuit, wherein the electronic integrated circuit is arranged to receive the one or more electronic signals from the photonic integrated circuit.