Coreray: Leading Fiber Optic Switch Manufacturer - MEMS & Mechanical Optical Solutions

Introduction

As fiber‑optic networks evolve to support 400G, 800G, and beyond, coherent transmission has become the backbone of long‑haul and metro networks. Coherent systems encode information in the phase and polarization of light, making them inherently sensitive to polarization disturbances. Any uncontrolled change in the state of polarization (SOP) can lead to signal degradation, increased bit error rates, and system outages. This is where polarization‑maintaining optical switches play a vital role. By preserving the polarization state throughout the switching process, they ensure signal integrity in critical applications such as reconfigurable optical add‑drop multiplexers (ROADMs), protection switching, and test equipment.

In this article, we explore the technology behind PM switches, their key performance parameters, real‑world applications, and how choosing the right optical switch manufacturer like Coreray can future‑proof your network.

1. The Principle of Polarization Maintenance

Standard single‑mode fiber does not preserve polarization; the SOP evolves randomly along the fiber due to stress, temperature changes, and manufacturing imperfections. Polarization‑maintaining fiber, on the other hand, introduces strong birefringence – typically through stress rods placed symmetrically around the core. This creates two orthogonal polarization axes (fast and slow) that maintain the launched polarization if the input light is aligned with one of them.

A polarization‑maintaining optical switch must:

·         Use PM fiber and align its axes consistently across all ports.

·         Ensure that the optical path inside the switch does not scramble the polarization.

·         Provide high polarization extinction ratio (PER) at the output, indicating how well the orthogonal polarization is suppressed.

Coreray’s OSW‑1550PM series achieves this by employing precision‑aligned PM components and careful assembly techniques, guaranteeing PER ≥20 dB over the entire operating temperature range.

2. Key Parameters of PM Optical Switches

2.1 Polarization Extinction Ratio (PER)

PER is the most critical metric. It measures the ratio of optical power in the desired polarization axis to that in the undesired axis. A high PER (≥20 dB) ensures that the signal remains in the intended polarization state, which is essential for coherent receivers and interferometric sensors.

2.2 Insertion Loss

Low insertion loss minimizes signal attenuation. The OSW‑1550PM features ≤0.8 dB typical loss, which helps maintain link budgets in long‑haul or high‑loss paths.

2.3 Switching Time

For protection switching and test automation, fast response is crucial. With ≤10 ms switching time, the OSW‑1550PM can rapidly reroute traffic or select different test channels.

2.4 Crosstalk

High isolation (≥60 dB) prevents signals from leaking between channels, avoiding interference in multiplexed systems.

2.5 Environmental Stability

PM switches must maintain performance across temperature variations. The OSW‑1550PM is specified from -10 to +60°C, with minimal change in loss and PER.

3. Real‑World Applications

3.1 Coherent Transceiver Testing

In R&D labs, engineers need to characterize transceivers under different polarization conditions. A PM switch can quickly connect a device under test to a polarization controller or a reference receiver, enabling automated measurement of polarization‑dependent parameters.

3.2 Fiber Optic Sensing

Distributed acoustic sensing (DAS) and interferometric sensors rely on maintaining polarization to detect phase shifts. PM switches allow time‑division multiplexing of multiple sensing fibers while preserving signal fidelity.

3.3 Quantum Key Distribution (QKD)

Quantum communication often uses polarization encoding. PM switches are used to route single photons without disturbing their quantum state, a requirement that ordinary switches cannot meet.

3.4 Reconfigurable Networks

In ROADM nodes, PM switches can be used to route signals while maintaining polarization alignment for downstream coherent receivers, eliminating the need for additional polarization tracking.

4. PM Switch vs. Standard Optical Switch: A Comparison

Choosing the right type depends on your system’s sensitivity to polarization. For polarization‑agnostic links, a standard switch suffices. For advanced systems, a PM switch is indispensable.

5. Why Coreray for Your PM Optical Switch Needs?

Coreray has extensive experience in designing and manufacturing custom fiber optic switches, including both MEMS and mechanical technologies. Our OSW‑1550PM series benefits from:

·         Precision alignment – Automated fusion splicing and axis alignment ensure consistent PER.

·         Rigorous testing – Every unit undergoes temperature cycling and burn‑in to verify performance.

·         Customization – We offer tail lengths, connector types (FC/APC, LC/APC, SC/APC), and even special fiber coatings.

·         Global support – Our engineering team assists with integration and troubleshooting.

Whether you need a benchtop switch for lab use or a rack‑mount module for industrial deployment, Coreray delivers reliable, high‑performance solutions.

Conclusion

As optical networks become more sophisticated, the ability to control and maintain polarization is no longer optional—it is a necessity. Polarization‑maintaining optical switches provide the essential function of routing signals while preserving their polarization state, enabling coherent communication, advanced sensing, and quantum technologies. The OSW‑1550PM from Coreray combines high PER, low loss, fast switching, and robust industrial design in a compact benchtop form factor, making it the ideal choice for engineers and system integrators.

When selecting a polarization‑maintaining optical switch, trust Coreray to deliver the quality and performance your application demands. Contact us today to discuss your custom requirements.