CFOT - Certified Fiber Optic Technician Splicing Techniques Questions and Answers — Questions and Answers
Question 1: A technician performs a fusion splice but the OTDR trace shows a significant loss of 0.5 dB. Microscopic inspection of a subsequent cleave from the same cleaver reveals a jagged, angled end-face. Which of the following is the MOST likely cause of the high splice loss?
- Incorrect fusion splicer arc power
- Contamination on the fiber surface
- A worn-out or damaged cleaver blade (Correct answer)
- Mismatched fiber core diameters
Correct answer: A worn-out or damaged cleaver blade
A high-quality splice requires a perfectly flat and perpendicular fiber end-face. A worn, chipped, or dirty cleaver blade will produce a poor cleave with imperfections like lips, chips, or angles, preventing the fibers from aligning and fusing correctly, which results in high signal loss.
Question 2: When comparing fusion splicing and mechanical splicing, which statement is generally true?
- Mechanical splicing offers lower insertion loss and better long-term reliability.
- Fusion splicing requires a lower initial investment in tools and equipment.
- Mechanical splicing physically melts and welds the two fibers together.
- Fusion splicing results in a more permanent bond with lower typical insertion loss. (Correct answer)
Correct answer: Fusion splicing results in a more permanent bond with lower typical insertion loss.
Fusion splicing uses an electric arc to weld two fibers together, creating a continuous, permanent connection. This method typically results in a very low insertion loss (often <0.1 dB) and excellent back reflection performance, making it superior in performance to mechanical splicing, which simply aligns the fibers in a housing.
Question 3: A technician is preparing to protect a newly completed fusion splice. What is the correct procedure regarding the heat-shrink splice protection sleeve?
- Apply the sleeve after the splice has been placed in the splice tray.
- Slide the sleeve onto one of the fibers BEFORE performing the fusion splice. (Correct answer)
- Select a sleeve that is shorter than the stripped fiber area.
- Heat the sleeve with a handheld lighter until it shrinks tightly.
Correct answer: Slide the sleeve onto one of the fibers BEFORE performing the fusion splice.
The splice protection sleeve must be placed onto one of the fiber strands before the fibers are stripped, cleaved, and fused. If this step is forgotten, the splice would have to be broken and redone to install the sleeve. After splicing, the sleeve is centered over the bare fiber and heated in the fusion splicer's oven to shrink and seal it.
Question 4: Which of the following describes the primary purpose of the 'cleaving' step in the fiber optic splicing process?
- To strip the outer jacket and buffer coatings from the fiber.
- To melt the fiber ends together using an electric arc.
- To create a precise, flat, and perpendicular end-face on the fiber. (Correct answer)
- To clean any contaminants from the bare fiber using isopropyl alcohol.
Correct answer: To create a precise, flat, and perpendicular end-face on the fiber.
Cleaving is the critical process of scoring and breaking the glass fiber to produce a perfectly smooth, flat end-face that is exactly 90 degrees to the fiber axis. This precise surface is essential for proper light transmission across the splice point with minimal loss or reflection.
Question 5: During a fusion splice, the technician notices tiny air pockets or voids near the splice point on the splicer's screen, and the resulting splice has high loss. This common defect is often referred to as:
- Cladding mismatch
- Hackle
- Bubbles or inclusions (Correct answer)
- Core runout
Correct answer: Bubbles or inclusions
Bubbles or inclusions are voids that can form in the glass during the fusion process. They are often caused by contamination on the fiber end-faces (which burns off and creates gas) or incorrect fusion parameters, such as excessive arc power or duration. These defects disrupt the light path and increase splice loss.
Question 6: What is the primary function of a heat-shrinkable splice protection sleeve used after a fusion splice?
- To increase the numerical aperture of the splice point.
- To provide mechanical strength and environmental protection to the bare splice. (Correct answer)
- To act as an index-matching gel to reduce back reflection.
- To align the fibers automatically before the fusion process.
Correct answer: To provide mechanical strength and environmental protection to the bare splice.
After a fusion splice, the section of bare fiber is fragile and exposed. A splice protection sleeve, which consists of an outer shrink tube, an inner adhesive liner, and a strength member (often a steel rod), is heated to shrink around the splice, providing rigidity, strength, and protection from moisture and handling.
CFOT - Certified Fiber Optic Technician Splicing Techniques Questions and Answers
A technician performs a fusion splice but the OTDR trace shows a significant loss of 0.5 dB.
Microscopic inspection of a subsequent cleave from the same cleaver reveals a jagged, angled end-face.
Which of the following is the MOST likely cause of the high splice loss?