Lossless 1 × 4 Silicon Photonic ROADM Based on a Monolithic Integrated Erbium Doped Waveguide Amplifier on a Si3N4 Platform

Duringthe past years, incorporating Οptical Circuit Switches (OCS) in high-bandwidth optical interconnects has outlined the critical challenges of achieving ultra-low fiber-to-fiber losses (FtF) and constantly decreasing costs for Photonic Integrated Circuits (PICs). This work aims to simultaneously satisfy both the low-loss and low-cost requirements by bringing two of the most successful example-technologies in the history of optics, i.e., EDFAs and ROADMs to a common Si
₃
N
₄
platform. In particular, the proof-of-concept operation of a lossless four-port Silicon Photonic (SiPho) ROADM is experimentally presented for the first time based on two PIC prototypes on a Si
₃
N
₄
platform, including a monolithic-integrated 5.9 cm-long spiral Al
₂
O
₃
:Er
³⁺
Erbium Doped Waveguide Amplifier (EDWA) with 15 dB signal enhancement capabilities and a lattice MZI-interleaver ROAM layout with 100 GHz channel spacing. Considering an ultra-low 2.55 dB FtF loss of the ROADM along with 0.5 dB loss for each of the two coupling-interfaces between the Si
₃
N
₄
and Al
₂
O
₃
:Er
³⁺
waveguide layers, a cumulative loss of 3.55 dB is obtained, which can be compensated by the 3.6 dB net gain provided by the EDWA to four incoming WDM signals of −1.7 dBm/channel. Lossless wavelength-routing operation is validated at up to 240 Gb/s WDM (4λ × 60 Gb/s) data traffic, while the cascadability of the proposed device is benchmarked in a realistic two-stage optical bus topology with 10 km single mode fiber that selectively routes 4λ × 25 Gb/s WDM data channels to any of its eight Drop output ports. This work forms the first demonstration of lossless ROADM operation exclusively on SiPho technology, highlighting a promising roadmap for large scale SiPho switching matrices and more complex PICs co-integrated with EDWAs.