Densely integrated low polarization dependent 8 × 8 optical switch for optical network applications

We investigate and demonstrate a modular non-blocking 8 × 8 photonic integrated switch configuration based on broadcast& select to route signals to all possible outputs. The photonic integrated switch is based on InP active/passive technology and exploits semiconductor optical amplifiers (SOA) as an optical switch and amplifier. In InP photonic integrated circuits, the growth rate enhancement (GRE) effect during selective area epitaxy limits the high-density integration of a compact array of SOAs, requiring a minimum pitch exceeding 100 μm for the butt-joint co-integration technique. Over time, the increasing maturity of InP PIC has enabled the fabrication of progressively scalable, complex, and compact switch circuits with high radix. Using a recently developed technique, SOAs can be placed densely - nearly five times more densely by narrowing the active island width from 20 μm to 8 μm - allowing flexibility in designing PIC switches based on SOAs. Here, we report and demonstrate, for the first time, an ultra-compact, polarization-insensitive 8 × 8 switch by positioning SOA arrays with a 60 μm pitch in an active-passive integrated InP platform. Multiple measured paths show promising results: gain over 20 dB, PDG under 3 dB, and high OSNR over 40 dB across the full C-band. We demonstrated that the switch exhibits a high extinction ratio, enabling effective crosstalk suppression between adjacent channels. Experimental data transmission assessments demonstrate operation at high bit rates of 30 Gbps with a low power penalty of less than 1 dB at a BER of 10-9. The switch's dynamic power penalty range exhibits a wide variation of over 20 dB, along with an input power dynamic range of over 15 dB for a power penalty of less than 3 dB at 10 Gbps and 30 Gbps NRZ signals. This demonstration paves the way for supporting compact, scalable, and high-speed commercial interconnect technologies for integrated optical devices.