Terminating fiber LC connectors requires precision and specialized equipment to achieve optimal optical performance. This comprehensive guide outlines the step-by-step process, drawing from industry best practices.
Necessary Tools and Materials
Before starting, assemble the necessary tools and materials:
- Fiber optic stripper – to remove cable jacketing and buffer
- Visual fault locator (VFL) – to test continuity
- Fiber cleaver – for precise cleaves
- Isopropyl alcohol and cleaning wipes
- Polishing film sheets (12 μm to 0.5 μm grits)
- LC inspection microscope – 200x or 400x magnification
Use only high-quality, dedicated fiber optic tools from reputed manufacturers. Avoid improvised solutions.
Step 1 – Prepare the Fiber
First, the fiber cable must be precisely stripped and cleaned:
- Secure the cable in a clamping fixture on a stable surface.
- Use the fiber stripper to remove 30-40 mm of outer jacketing, exposing the bare fiber underneath. Take care to not nick the glass.
- Thoroughly wipe the fiber with lint-free wipes and alcohol to remove any contaminants.
Pro Tip: Always store stripped fibers in protective sleeves to avoid damage.
Step 2 – Cleave the Fiber
Cleaving creates a pristine end-face on the fiber essential for connectivity:
- Insert the stripped fiber into the cleaver, ensuring it is tension-free. Refer to manufacturer instructions.
- Actuate the cleaver’s blade to make a clean, perpendicular score on the glass.
- The cleave angle must be less than 0.5° relative to perpendicular as per industry standards.
Warning: Even microscopic defects in the cleave can severely compromise optical transmission.
Step 3 – Assemble the LC Connector
With the fiber cleaved, assemble the connector precisely:
- For epoxy/adhesive connectors, inject a small amount into the ferrule.
- Insert the fiber until it protrudes slightly from the ferrule tip.
- Cure the epoxy per curing specifications before polishing.
- For pre-polished connectors, carefully insert into ferrule and secure.
Maintaining pristine cleanliness is vital during connector assembly.
Step 4 – Polish the Ferrule Tip
The termination process culminates in a polished ferrule tip:
- Using a figure-eight motion, polish the tip using film sheets of decreasing grit: 12 μm, 5 μm, 1 μm.
- Finish with a 0.5 μm grit for a smooth, mirror-like surface essentail for physical contact.
- Between polishing steps, thoroughly clean the tip using pressurized air and alcohol.
- After the final polish, inspect using a fiber microscope to check for defects.
Note: Insufficient polishing severely increases loss and reflections.
Final Termination and Validation
With polishing complete, conclude the termination:
- Use a simple VFL tester to validate basic continuity from end-to-end.
- Measure insertion loss (IL) and return loss (RL) using an optical loss test set (OLTS).
- Acceptable loss margins for LC connectors are ≤ 0.3 dB IL and ≥ -50 dB RL.
- Retain test records along with quality inspection reports.
Following best practices during termination enables reliable, low-loss optical connections with LC connectors. However, re-furbishment may eventually be necessary for continued optimal performance.
FAQs About Terminating LC Connectors
Q: What causes high insertion loss?
High loss is typically due to contamination, poor cleaving or insufficient epoxy curing. Re-clean and re-terminate the connector.
Q: Can I reuse factory-terminated connectors?
No, trying to reuse pre-polished connectors damages the internal alignment, increasing loss. Always use pristine components.
Q: What is an acceptable loss for multimode LC connectors?
Multimode connectors specified for modal bandwidth >500 MHz can tolerate up to 1.0 dB of loss as per ANSI/TIA.
Conclusion
Terminating LC connectors for optimal loss requires precision, specialized equipment and adhering to industry best practices. However, with experience and adequate quality control, technicians can reliably achieve less than 0.3 dB loss for single-mode links. Maintaining pristine cleanliness of tools, fibers and work areas is equally essential throughout the termination process.
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