PM Patch Cords: Precision Links for Polarization-Critical Optical Systems
In advanced photonic applications where polarization state stability is paramount—such as fiber optic gyroscopes (FOGs), coherent communications, quantum optics, or high-power laser delivery—standard single-mode fibers are inadequate due to their random birefringence. Polarization-Maintaining (PM) patch cords serve as the essential “bridges” in these systems, connecting functional modules to PM components. Their core function is to preserve the orientation of linearly polarized light, ensuring transmission with minimal polarization crosstalk and maximum extinction ratio.
Feiyi OEO offers a comprehensive range of high-performance PM patch cords and pigtails. Manufactured with precision from industry-standard “PANDA” PM fiber, they guarantee accurate alignment of the polarization axis (slow or fast axis) at every connection point, forming the reliable foundation for stable, polarization-sensitive systems.
Part 1: By Fiber Count — Tailored for System Architecture
The construction of a PM fiber assembly directly determines its integration method and performance within a system.
1. Single-Fiber PM Patch Cord
- Construction: A single strand of PM fiber, terminated with a standard fiber connector (e.g., FC/PC, FC/APC, LC) on one end and either bare fiber or a connector on the other.
- Key Specifications:
- Precision Axis Alignment: The connector key is aligned to the internal PM fiber’s principal axis (typically the slow axis) with high angular accuracy (<1° is standard) using specialized microscopes and rotational fixtures.
- High Extinction Ratio (ER): Typically >20 dB, with premium versions exceeding 25 dB, ensuring purity of the dominant polarization mode.
- Low Insertion Loss (IL): Typically <0.5 dB, minimizing signal power loss.
- Primary Applications:
- Connecting the output of a PM light source (e.g., a DFB laser) to downstream components.
- Serving as input/output pigtails for PM devices (isolators, modulators).
- Acting as a reference cable for system testing and characterization.
2. Dual-Fiber (Pigtail) PM Assembly
- Construction: Two PM fibers arranged in parallel, terminated together in a multi-fiber connector (common: 2-fiber LC/MPO) on one end and as separated, stripped fibers on the other.
- Key Specifications:
- Dual-Channel Polarization Maintenance: Maintains the polarization state in two independent, parallel optical paths within one assembly, with very low crosstalk between channels.
- Consistent Axis Alignment: Ensures the polarization axes of both fibers are oriented identically at the connector interface, which is critical for interferometric applications.
- Excellent Polarization Holding and Phase Stability.
- Primary Applications:
- Fiber Optic Gyroscopes (FOGs): Forming the core links of the Sagnac interferometer loop, connected to integrated optical chips (IOCs).
- Input/output tails for PM couplers/splitters.
- Any system requiring synchronized dual-channel PM light input/output.
Part 2: By Operating Wavelength — Optimized for Specific Bands
The performance of a PM patch cord, particularly its IL and ER, is optimized for specific wavelength windows.
1. 850 nm / 980 nm Window
- Fiber Type: PM fiber optimized for shorter wavelengths.
- Application Focus: Pump laser coupling, specific sensing systems.
2. 1310 nm Window (O-Band)
- Industry Standard Window: Widely used in traditional telecom, datacom, and many sensing systems.
- Product Features: Available in standard and high-ER grades, compatible with most 1310nm lasers and components.
3. 1550 nm Window (C/L-Bands)
- Core Application Window: The primary operating band for modern high-speed coherent communications, FOGs, quantum key distribution (QKD), and high-precision interferometric sensing.
- Product Features:
- Ultra-Low Loss: Optimized for long-haul transmission.
- High Extinction Ratio: Designed for applications demanding extreme polarization purity, such as interferometry.
- Bend-Insensitive: Suitable for dense packaging within equipment.
Why Choose Feiyi OEO PM Patch Cords?
- Precision Axis Alignment Technology: Proprietary calibration processes ensure every patch cord offers exceptional and consistent polarization alignment accuracy, with reliable axis marking.
- Full Customization Capability:
- Connector Types: FC, SC, LC, ST, E2000, etc., with PC/UPC/APC polish.
- Cable Length: Custom lengths from centimeters to hundreds of meters.
- Jacket Material: PVC, OFNR, armored, etc., for varied mechanical and environmental needs.
- Special Requirements: Available in high-power (specialized end-face treatment), radiation-resistant, or space-qualified ruggedized versions.
- Rigorous Quality Verification: Each patch cord is 100% tested for Insertion Loss, Return Loss, and Extinction Ratio, with data reports provided.
Providing the stable, reliable optical link for your polarization-critical system.
Explore our full range of PM Fiber Assemblies for detailed specifications:
https://www.feiyi-oeo.com/product-category/polarization-maintaining/pm-pigtail/
Need a customized solution for your specific application? Our optical engineering team is ready to assist.