The ultra-fast internet you rely on every day is made possible through fiber optic cables which are thin strands of glass or plastic. However, you know they go through an extremely complex manufacturing process involving advanced technology, extreme temperatures, and thorough testing. Let’s take you inside the fascinating world of fiber optic cable production!
Figure no 1 Fiber Optic Manufacturing Process Guide
1) Key Requirements for Fiber Optic Cable Manufacturing
It is essential to comprehend key components and materials associated with the fiber optic cable, along with the setup requirements, prior to understanding fiber optic cable production.
i) Understanding Fiber Optic Cable Structure: First of all, keep in mind that a fiber optic cable is made of four primary layers: One is the core (the central transparent portion transmits light signals ). Similarly, the second one is cladding which is a light-reflecting portion surrounding the core to retain light internally mitigating signal loss ).
The next comes buffer coating which is an abrasively resistant protective layer that safeguards the fiber from scratches and external damage). The last layer is Jacket which provides insulation from the surrounding environment.
Figure no 2 Prerequisites for fiber optic cable production
ii) Material Selection: Besides this, it is imperative to choose the right materials to achieve optimal performance and longevity. So, look at the given table helping you quickly decide which material you have to opt for!
| Core | Cladding | Buffer Coating | Strength Member | Outer Jacket | |
| Materials | Silica glass (99.999% pure) | Fluorine-doped silica | UV-cured acrylate | Kevlar, steel, fiberglass | PVC, LSZH, polyethylene |
iii) Production Requirements: Moreover, fiber optic cables manufcaturing requires precision machinery, clean rooms, and stringent temperature control. For example, the fiber drawing process necessitates heating silica over 2000 degrees Celsius with a maintained diameter at 125 microns with a variation of only ±1-micron.
iv) Quality Control Measures: However, before scaling production, fiber cable quality needs to be evaluated. For single-mode fibers, signal loss, or attenuation needs to be below 0.2 dB/km while the cable should withstand a tensile force of no less than 50 Newtons to ensure enduring durability.
Thus, by adhering to these conditions, it is possible to manufacture fiber optic cables capable of uninterrupted reliable performance of 25+ years.
2) Step-by-Step Guide to Fiber Optic Cable Production Process
Figure no 3 Fiber Optic cable production flow sheet
i) Step 1: Preform Manufacturing
The first stage starts with a preform from which an optical fiber with superior attributes can be drawn. Imagine preform as a “blueprint” controlling the structure of a fiber optic cable, and thus all the processes that dictate how efficiently light traverses through it.
Figure no 4 Preform manufacturing for Fiber cable
- How is a Preform Made?
To achieve ultra-high performance, the versatile grade silica (99.999% purity) is used, and both core and cladding are deposited in layers. Here, keep in mind that every bit of contamination, even if it is midstream, can solely result in loss of signal and so adheres to a certain procedure.
Figure no 5 MCVD Process for fiber optic cable manufacturing
- Three Common Preform Fabrication Methods
| Process | Best for | Pros | Cons | |
| MCVD (Modified Chemical Vapor Deposition) | Gas heated inside a rotating silica tube to form layers | High-precision telecom fibers | Precise refractive index control | Low production capacity, high cost |
| OVD (Outside Vapor Deposition) | Silica particles deposited on a spinning rod, then sintered | Mass production of standard fibers | Good fiber property control | Complex setup |
| VAD (Vapor Axial Deposition) | Vertical deposition builds large preforms | High-volume, low-cost fiber | Efficient large-scale production | Requires advanced equipment |
With these steps, the preform is then sintered at 1600-1800°C to get rid of air bubbles and to achieve unmatched optical clarity. After these processes, a solid transparent rod is yielded which can now be shifted into fiber drawing; which is the next stage.
Step 2: Fiber Drawing Process
After preparing your preform, now comes the step of converting it to ultra-thin optical fiber. This happens in a fiber drawing tower, which is a highly sophisticated system that manages every detail to uphold precision.
- Description of Fiber Drawing Process Work
- First of all, a furnace heats the tip of your preform to around 2000-2200 °C. Until the tip get softened.
- Next, the melted silica is pulled by gravity and a thin fiber strand is formed.
- Now, the diameter of the fiber is continually monitored by a laser monitoring system. It ensures the fiber is exactly 125 microns ± 1 micron.
Figure no 6 Fiber Drawing Tower
- Applying the Primary Coating
Before the fiber cools, a polymer coating that is UV-cured is immediately applied so that the fiber receives protection from external damage. This coating process is done in milliseconds to ensure no microscopic cracks form.
- Cooling and Winding
After applying primary coating the fiber moves to the cooling chamber to gain mechanical strength. Now, this fiber is wound on a spool.
Step 3: Fiber Testing and Quality Control
Before proceeding forward, the fiber must undergo thorough testing. This is because signal loss or mechanical malfunctions are severely harmful and therefore, multi-step quality assessment measures must be put into place.
- Optical Performance Testing
| Purpose | Test Method | Applicable Cable Types | Standard Values | |
| Attenuation Test | Measures signal loss | Light signal is sent through fiber, and loss is recorded | Single-mode, multi-mode fibers | ≤ 0.35 dB/km at 1310 nm (SMF), ≤ 3.0 dB/km at 850 nm (MMF) |
| Dispersion Test | Evaluates signal broadening | OTDR analysis | Long-haul, DWDM, submarine cables | Chromatic: ≤ 18 ps/nm·km, Polarization Mode: ≤ 0.2 ps/√km |
| Return Loss Test | Checks reflected signal power | OTDR or Power Meter | All fiber optic cables | ≥ 55 dB for single-mode, ≥ 30 dB for multi-mode |
| Insertion Loss Test | Measures connection loss | Power measurement before & after | Patch cords, connectors, spliced cables | ≤ 0.3 dB per connector |
| Polarization Mode Dispersion (PMD) Test | Assesses signal distortion | Polarization analysis | High-speed, long-distance fibers | ≤ 0.2 ps/√km |
- Mechanical Strength Testing
| Purpose | Test Methos | Applicable Cable Types | Standard Values | |
| Tensile Strength Test | Withstands pulling forces | Stretched until failure | Aerial, underground, submarine cables | 600–2700 N |
| Crush Resistance Test | Resists compression | Force applied to cable | Armored, direct-burial cables | 1000–3000 N/10 cm |
| Impact Test | Withstands sudden impacts | Dropped weight test | Indoor, outdoor, industrial cables | 1–10 impacts, 1–2 Nm |
| Bending Test | Assesses flexibility | Bent at various angles | Tight-buffered, patch cords, riser cables | 20–50 cycles at 20× diameter |
| Water Penetration Test | Prevents moisture ingress | Water exposure test | Gel-filled, outdoor, submarine cables | No water penetration (24 hrs) |
- Final Defect Inspection:
Microscopic imaging allows for the detection of micro-cracks, bubbles, or irregular sido coatings and should only be done once the fiber is accepted. fibers that do not meet the accepted standards are obliterated to ensure only quality fibers are employed.
Step 4: Secondary Coating and Buffering
This is the stage where fibers can be guarded for more durability in harsher conditions.
- Applying the Secondary Protective Layer
A second layer of acrylate or thermoplastic is placed on the primary coating to further cover the fiber from moisture, chemical Exposure, and mechanical Stress.
- Choosing the Right Buffering Technique
? Loose Tube Buffering: The fiber is loosely placed in a plastic tube that contains gel or air space, providing flexibility and resistance to extreme temperatures.
? Tight Buffering: This involves applying a protective layer that is firmly attached to the fiber. This makes the fiber more robust for direct installations.
The proper buffering allows the fiber to withstand underground and aerial installations as well as harsh marine conditions.
Step 5: Cable Assembly and Jacketing
The prep work is now done, the fiber is ready to be made into a complete fiber optic cable.
- Stranding Multiple Fibers Together
With multi-fiber cables, fibers are placed in a specific order inside a central tube. As a measure against damage, the manufacturers include Kevlar, steel wires, or fiberglass rods to reinforce the tube.
- Adding the Outer Protective Jacket
An outer sheath is added to guard your cable against environmental risks. The type of material selection is based on the intended use:
| Jacket material | Best For |
| PVC (Polyvinyl Chloride) | Indoor use, cost-effective |
| LSZH (Low Smoke Zero Halogen) | Fire-resistant, ideal for enclosed spaces |
| Polyethylene (PE) | Outdoor and underground applications |
| Armoured Cable (Steel/Tape) | High-protection areas, direct burial installations |
- Final Moisture and Fire Protection
Fiber optic cable manufacturers place water-blocking gels or tapes inside the cable to ensure that it remains inaccessible to water. In closing the cable, heat-resistant materials are used when there are concerns about the cable being exposed to fire.
Apart from these processes, final testing remains the last step to complete the fiber optic cable.
Step 6: Final Testing and Quality Assurance
Your cable undergoes a series of telecom, internet, and industrial standard tests to assess its usability in those fields. The cables also undergo final inspection which includes checking the visual aspects, measuring the diameter, and marking the capsule. After undergoing all tests, the cable is prepared for shipping and installation to provide high-speed, long-distance communication with little signal loss.
3) Final Verdict
In short, the construction of fiber optic cables is a highly specialized and advanced level procedure. Each step, starting from the preform fabrication to final quality assurance tests, needs to be completed with utmost attention so that minimal signal loss occurs and maximum durability is achieved. With the world now expecting high-speed data transfers, innovation in fiber optics is continuously increasing for performance optimization. With unparalleled quality certifications and cutting-edge manufacturing units, Dekam is your go-to provider for premium fiber optic cables. So, contact us today!
