Optical Fiber Splicing
ITU-T Recommendation L.400
Jun Carbonell, PECE
Inno Instruments, Inc.
ECM Networks
Optical Fiber Splicing
ITU-T Recommendation L.400
Jun Carbonell, PECE
Inno Instruments, Inc. - ECM Networks
ITU-T recommendation Section L defines industry standards on
Construction, installation and protection of cables and other
Elements of outside plant
Section L.400
Fiber Optic Splicing
• Methodology
• Guidelines
• Testing
Fiber Optic Applications in Communications
• International/ Domestic/ Regional Backbone Network
• Central Offices Interconnection
• Digital Loop Carrier Backhaul / DSLAM Backbone
• Mobile Phone Base Station Interconnection
• Fiber to the Home (GPON)
Single-mode Fibers have been developed for
each application
• G.652 (Non-Dispersion Shift Fiber) - commonly used
• G.653 (Dispersion Shift Fiber) – Reduced Core Size for EDFA
• G.654 (Ultra Low Loss Optical Fiber) – Submarine Cables
• G.655 (Non-Zero Dispersion-Shifted Fiber) – Regional/DFON
• G.656 (Medium Dispersion Fiber) – Regional/DFON
• G.657 (Bend Insensitive Fiber) - FTTH
Fiber to the Building
Enterprise minimum fiber
requirement per ISP/Telco
4 Fibers (1 pair active &
1 pair Spare)
x x x x x
Fusion SPLICES - X
Fiber to the Home Network
Main Components (Active & Passive)
Network Access Point Optical Network Unit
Optical Node Unit
Local Convergence Point (NAP) (ONU)
Local Concentration Port
(LCP) PASSIVE ACTIVE
Optical Line Termination Unit
x x
(OLT) PASSIVE
ACTIVE
x x
x x x x
Fiber Optic Cable
Mechanical
Fiber Optic Cable
G.652d
G.657A2
SPLICES
Fusion
Fusion SPLICES 2nd OPTICAL SPLITTER
It splits 1 Fiber from LCP to
1st OPTICAL SPLITTER
SPLICES It splits the Main (1) Fiber to
8 Fibers connected to Subscibers
(Typical Loss: 9.6dB to 10.2dB)
8 Fibers to be fed to 8 NAP
(Typical Loss: 9.6dB to 10.2dB)
Other Passive Optic Network (PON) Technology application
1 x 8 Splitter
IP CAMERA
Network 1 x 8 Splitter Fiber
Video Recorder ONU
Fiber
ONU
Fiber
SERVER OLT
To other
Splitter
ONU
IP-PBX ONU
WiFi Computer
Access Point Terminal
Internet
Advantages: INTERCOM/
PHONE
a. No distance Limitation (up to 20Km)
b. Less Active Devices ( Network Switches & Routers)
c. All IP applications in one fiber optic network
ITU-T Recommendation L.400
Section 4.1 and 5.1 refers to Fusion Splices
Section 4.2 and 5.2 refers to Mechanical Splices
Objective is to obtain a Low or
Negligible splice loss
90% of Fiber Optic Network are connected
Using Fusion Splice
Fusion Splicing Methodology
ITU-T L.400 Section 4 and 5
a. Fiber cleaning and Preparation
b. Coating Stripping
c. Cleaning of bare fiber ends
d. Fiber cleaving
e. Splicing
5.5.1.2 Fusion Splicing
5.5.1.3 Proof Test
5.5.1.4 Splice Protection
5.6 Field Splice Loss Measurement
Fusion Splicing Methodology
Section 4 and 5
a. Fiber cleaning and Preparation
Removal of gel or any water-repellant chemical on the
Fiber coating using fabric/paper tissue soaked with
commercially available solvents or acrylic-friendly
chemicals (Limonene Base)
Fusion Splicing Methodology
Section 4 and 5
b. Coating Stripping
Removal of primary and secondary (if applicable) coating
of bare fibers using Chemical, thermal or mechanical method.
In case of chemical, manufacturer should supply safety
information on chemical used. Mostly used method is mechanical.
For Ribbon Type Fibers, holders must be provided to strip, clean and
splice to ensure good alignment.
ITU-T Recommendation L.400
1. Removal of Coating
250 micron Coating
Exposing the Cladding & Core
Fiber Optic Strippers
125, 900 micron and 3mm Stripper
125 & 900 micron Stripper (Mechanical) (Mechanical)
125 & 900 micron Thermal Stripper Ribbon Fiber Thermal Stripper
POORLY MAINTAINED STRIPPER CAN
CREATE SCRATCHES ON CLADDING
Fusion Splicing Methodology
Section 4 and 5
c. Cleaning of bare fiber ends
Alcohol Dispenser Lint free cloth/tissue
Fusion Splicing Methodology
Section 4 and 5
c. Cleaning of bare fiber ends
Isopropyl Alcohol Isopropyl Alcohol
>95% < 70%
Fusion Splicing Methodology
Section 4 and 5
d. Fiber cleaving
The bare fiber ends shall be cleaved perpendicularly to the
longitudinal axis; the cut surface should be mirror-like without
chip or hackle.
For Fusion splices, end angles should be less than 1 degree
For Mechanical splice, end angles should be less than 4 degrees
Cleaver should always be cleaned.
GOOD CLEAVER, GOOD SPLICE
ITU-T Recommendation L.400
Coating
Coating
2. Cleaving the end of the fiber
Fiber to be CLEAVED
ITU-T Recommendation L.400
Very light scratch is made to
the fiber
CLEAVER
BLADE
ITU-T Recommendation L.400
Angle should not be more than 1˚
(fusion splicing)
Coating ≤ 1˚
Coating
2. Cleaving the end of the fiber
Rubber Grips of
Fiber Cleaver
Slight Cut
ONLY
Fiber Optic Cleaver
Rubber Grips
Fusion Splicing Methodology
Section 4 and 5
e. Splicing
5.5.1 Fusion Splicing (Permanent)
5.5.2 Mechanical Splicing (Semi-permanent)
Index Matching Gel
MECHANICAL (FIBER OPTIC) SPLICE
Index Matching Gel
Fusion Splicing
Fiber A Fiber B
Fusion Splicing Methodology
Section 4 and 5
5.5.1 Electric Arc Fusion Splicing
5.5.1.1 Control of the Splicing parameter and conditions
5.5.1.2 Fusion Splicing
5.5.1.3 Proof Test
5.5.1.4 Splice Protection
Fusion Splicing Methodology
Section 4 and 5
5.5.1 Electric Arc Fusion Splicing
5.5.1.1 Control of the Splicing parameter and conditions
Checking performance of Splicing Machine to adapt
on the following:
- Condition of Electrode
- Type of Fiber
- Environmental conditions
Factors Affecting Fusion Splicing
1. Tip of Electrode
3. Environment 2. Melting properties
of fiber
Condition of Electrode
Electrode Life is around 3500 to 4000 Splices
Brand New
Old Electrode
Electrode
(Rounded Tip)
(Sharp Tip)
ELECTRODE TIP DISCHARGE
Fiber
Physical
Fiber manufacturer
Dimensions
should comply
And
with this
Material
specifications
Properties
Fusion Splicing Methodology
Section 4 and 5
5.5.1 Electric Arc Fusion Splicing
5.5.1.1 Control of the Splicing parameter and conditions
“ARC Calibration” or “ARC Test” Features
This feature allow the fusion splicer to
Adjust the Electrode Power and position
Based on Temperature, Atmospheric Pressure
And Relative Humidity
5.5.1.1 Control of the Splicing parameter and conditions
ARC CALIBRATION
Machine will initially adjust the
Arc Power based on Temp, RH
and Pressure.
5.5.1.1 Control of the Splicing parameter and conditions
ARC CALIBRATION
Electrode will produce
ARC to melt the ends
of each fiber (Left and Fibers are stationary
Right) (no movement)
5.5.1.1 Control of the Splicing parameter and conditions
ARC CALIBRATION
Electrode will produce
ARC to melt the ends of
each fiber (Left and Right)
5.5.1.1 Control of the Splicing parameter and conditions
ARC CALIBRATION
Some Fusion Splicer
Can accommodate up to
3µm difference
12 12
IF “FIBER A” HAS THE SAME
PHYSICAL ATTRIBUTES WITH
“FIBER B”
THEY WILL HAVE THE SAME MELT
DISPLACEMENT
ARC CALIBRATION
12 18
This means “Fiber A” is not the
Same with “Fiber B”
If ARC Calibration is not performed, it might yield to a defective splice
Defective Fusion Splice Images
Fat or Bulging
Thinning
Line or Gap Separation
• LID (Light Injection & Detection)
The coated fiber is bent near the fiber tips to launch light
and detect light. The arrows denote the flow of control to or
from the microprocessor. Cannot splice if there if fiber is
working or with signal.
PAS (Profile Alignment System)
Components of a simplified fusion
splicer including heat source,
imaging lens, CCD, microprocessor,
and chucks for positioning and
aligning fiber tips. The thin arrows
denote the flow of control to or
from the microprocessor
Fiber Splice Method
Profile Alignment System (PAS)
Estimated Splice Loss Measurement
CORE ALIGNMENT
A B C D A’ B’ C’ D’
X X X X X X X X
X
X
X
X
X
X
X
X
A X X X X
X X
X X
X X X X X X X X
Estimated Splice Loss Measurement
CLADDING ALIGNMENT
A B C D A’ B’ C’ D’
X X X X X X X X
A
X X X X X X X X
Core is not visible since it
Only concern is cladding
Fusion Splicing Methodology
Section 4 and 5
5.5.1 Electric Arc Fusion Splicing
5.5.1.2 Fusion Splicing
Electric arcs heat the silica glass until it melts
in which fibers are longitudinally brought together
to obtain a geometrically continuous splice
Fusion Splicing
Fiber A Fiber B
Wavelengths and their Colors
1200nm to 1700nm
(Colorless or Invinsible)
(650nm) for VFL
(580nm)
Light Ray
Fiber Splice Method
Profile Alignment System (PAS)
Light signal is not reflected on the CCD
since 1310nm, 1490nm, 1550nm is not visible
so it can perform alignment
and splicing
FUSION SPLICING PROCESS
Electrode rods
1) Determination of fiber position/
fiber alignment
2) Pre-fusion
3) Stuffing and fusion
Fiber movement
4) Loss measurement
FUSION SPLICING OPERATION TIMING
(1) Fiber Setting
“ARC” cleaning
(2) Cleaning
(spattering) (sec)
(3) Fiber end check
Alignment ARC gap;
Gap between fiber ends (um)
(4) Start of discharge
Pre-fusion
time (sec)
Arc power
(1 - 16 steps)
(5) Start of insertion
Fusion
(6) Completion of insertion Time
(sec)
Lo: Length overlap (um)
(7) Completion of discharge
Estimated Splice Loss Measurement
CORE ALIGNMENT
A B C D A’ B’ C’ D’
X X X X X X X X
X
X
X
X
X
X
X
X
A X X X X
X X
X X
X X X X X X X X
Estimated Loss 0.00dB
Estimated Splice Loss Measurement
CLADDING ALIGNMENT
A B C D A’ B’ C’ D’
X X X X X X X X
A
X X X X X X X X
Estimated Loss 0.00dB
Core is not visible since it
Only concern is cladding
CAUSES OF EXTRINSIC SPLICE LOSS
Not Good Fiber end surface OK
Lip Chip Angle NOT OK
CAUSES OF EXTRINSIC SPLICE LOSS
E
Axial mis-alignment End separation
Angular mis-alignment
Fusion Splicing Methodology
Section 4 and 5
5.5.1 Electric Arc Fusion Splicing
5.5.1.3 Proof Test
Performing a tensile test on the completed
Splice by applying 2N on both ends
of the splice to ensure splice integrity
Fusion Splicing Methodology
Section 4 and 5
5.5.1.3 Proof Test
(2 Newtons Pull)
Fusion Splicing Methodology
Section 4 and 5
5.5.1 Electric Arc Fusion Splicing
5.5.1.4 Splice Protection
Protector is a mechanical device or restored coating,
that provides both mechanical and environmental
protection to the single or multiple splices.
It shall never affect neither the attenuation of the splice
nor its functional properties
Fusion Splicing Methodology
Section 4 and 5
Mechanical Splice Protector
Heat Shrinkable Splice Protector
Heat Shrinkable Protection Sleeve
Fiber Optic Splice Closure & Splice Tray
At least
60mm
At least
60mm
Protection Sleeves
Should be placed
Properly on fiber splice
Slot on fiber trays
5.6 Field Splice Loss Splice Measurement
A B C D A’ B’ C’ D’
X X X X X X X X
X
X
X
X
X X
X X
A X X X X
X X
X X
X X X X X X X X
Estimated Loss 0.00dB
OTDR Two-direction Testing to determine Splice Loss
Point A Splice point Point B
Point A Splice point Point B
Fusion Splicing
Fiber A Fiber B
A seamless or flawless splice is a good splice
Estimated Loss 0.00 dB
Can we conclude that this is the actual splice loss?
Same Mode Field Diameter
Fiber A Fiber B
Seamless Visual Connectivity (Physical Appearance)
Seen by our naked eye
If MFD of Fiber A is EQUAL to MFD of Fiber B
Seen by the Light Signal (OTDR Signal)
travelling inside the core
Different Mode Field Diameter
MAJOR CAUSE OF INTRINSIC LOSS
Fiber A Fiber B
Seamless Visual Connectivity (Physical Appearance)
Seen by our naked eye
If MFD of Fiber A is NOT EQUAL to MFD of Fiber B
Seen by the Light Signal (OTDR Signal)
travelling inside the core
Other INTRINSIC LOSSES
Off-center Fiber Cladding Diameter Mismatch
Numerical Aperture Mismatch Core Diameter Mismatch
(Multimode)
MODE FIELD DIAMETER
Core diameter
MFD@1310nm Core diameter MFD@1550nm 9 microns
9.2 microns 9 microns 10.4 microns
1310nm wavelength travels 1550nm wavelength travels
Slightly Outside the core Beyond the core
(part of the cladding)
In testing a splice loss, use 1310nm because it will
give us the actual condition of the core joint
Sample of G.652D Specification sheet
Fiber Manufacturer
Fiber Manufacturer
Cable Manufacturer
They source fibers from multiple vendors
A-B
B-A
SPLICE LOSS = [(LOSS A-B) + (LOSS B-A)] / 2
= [0.533 + (-.406)] / 2
= 0.0635
ITU-T G.671 Transmission Characteristics of
Optical Components and Subsystems
Section 5.13 – Acceptable Optical Splice Loss
Fiber to the Home Implementation: G.657A
G.657A1 or A2 – used in FTTH application
1x8 Optical Splitters
used in LCP and NAP (FTTH) Fiber Drop and Fiber Indoor
Cable (FTTH)
They are spliced together with G.652D
MFD of G652D vs. G657A1&2 vs. G657B2&3
Magnified view of
G.652D to G.657 Fusion Splice
G.652D G.657A2
Bend Sensitive Bend In Sensitive
The reason for the visible line in the splice is because of
the slight difference in material Composition of the Bend
Insensitive Fiber vs.G.652D fiber.
Magnified view of
G.652D to G.657 Fusion Splice
MFD=9.2µm MFD=9.2µm
This SPLICE is OK!
G.652D and G.657 Splicing
G657 Fiber G657 Fiber
G652 Fiber G652 Fiber
SUMMARY
To maximize the power budget in your fiber network,
reduce all sources of losses, especially the splice loss,
by observing ITU-T recommendations.
1. Proper selection of Fiber Optic Cable
2. Inform or train your technical personnel on proper
fiber optic cable preparation prior to splicing
3. Proper selection of Fusion Splicer
4. Proper Splice Loss Testing
jun.carbonell@ecmnetworks.com
