Comparison of Low Loss and Cost-Effectiveness Performance of Optical Cross-Connect Boxes

MEMS-based optical cross-connects achieve low insertion loss and high scalability, while silicon photonics OXCs offer integration advantages but generally higher loss for large port counts.

MEMS-Based Optical Cross-Connects

MEMS (Micro-Electro-Mechanical Systems) OXCs use micromechanical mirrors to steer optical beams between input and output ports, enabling all-optical switching without OEO conversion. A practical example is a 256 × 256-port MEMS OXC, which achieves an average insertion loss of 1.33 dB and a maximum loss below 2 dB for 238 × 238 active ports . Key design features include:

• Mirror size and pitch: 0.6-mm diameter mirrors on a 1-mm pitch optimize beam steering and minimize clipping losses.
• Fourier lens integration: Reduces beam divergence and improves fiber-to-microlens coupling efficiency.
• Crosstalk performance: Static crosstalk can reach 68 dB, while dynamic crosstalk is typically under 50 dB.
• Scalability: MEMS OXCs can scale to hundreds of ports while maintaining low loss and low crosstalk, making them suitable for core network applications . MEMS OXCs are particularly advantageous for high-bandwidth, low-latency networks, including data centers and intersatellite optical links, due to their fast switching speeds and low power consumption.

Silicon Photonics Optical Cross-Connects

Silicon photonics OXCs leverage integrated waveguides and thermo-optic or electro-optic phase shifters to route optical signals. Examples include 32 × 32 PILOSS switches, which demonstrate:

• Average fiber-to-fiber insertion loss: ~10.8 dB for 32 × 32 ports, higher than MEMS-based systems for comparable port counts .
• Polarization management: Polarization diversity schemes reduce polarization-dependent loss to <0.5 dB.
• Bandwidth: Operating bandwidths can exceed 100 nm with -30 dB crosstalk using Mach–Zehnder interferometer elements.
• Integration benefits: Compact footprint, CMOS compatibility, and potential for on-chip integration with electronics. While silicon photonics OXCs offer high integration density and potential for mass production, their insertion loss increases with port count, making them less favorable for very large-scale, low-loss applications compared to MEMS OXCs.

Comparative Summary

Conclusion

For low-loss, large-scale optical switching, MEMS-based OXCs currently outperform silicon photonics in terms of insertion loss, crosstalk, and port scalability. Silicon photonics OXCs, however, offer compact integration and potential for on-chip routing, making them suitable for smaller-scale or integrated network applications. The choice depends on the trade-off between low-loss performance and integration density, as well as the target network scale and application requirements .