Fiber Optic Coupler

Fiber optic splitter is an optical passive device that decomposes a fiber signal into two or more optical signals according to a predetermined proportion for output, and is connected to FTTH mode. According to the different principles of optical splitting and manufacturing processes, optical splitters can be divided into two types: fused biconical (FBT) and planar waveguide (PLC).

The FBT splitter is produced using the traditional taper coupler process, which bundles two or more coated optical fibers together, and then heats and melts them at high temperature on the taper puller. At the same time, it stretches to both sides and monitors the changes in the splitting ratio in real-time. After the splitting ratio meets the requirements, the melting and stretching process ends, and finally, a special waveguide structure in the form of a double cone is formed in the heating zone. One end retains a fiber optic cable (the rest is cut off) as the input end, and the other end serves as the multi-channel output end. By controlling the angle of fiber twisting and the length of stretching, different splitting ratios can be obtained. Finally, solidify the pulling cone area with curing adhesive onto a quartz substrate and insert it into a stainless steel tube.

At present, the mature cone pulling process can only pull 1×4 or less at a time. If output more, multiple 1×2 are used to connected together and then pack as a set in a module.  

Production Process

Fiber Coupler Types

Yingda design and make all kinds of fiber optic couplers and splitters with ISO certified. Custom final package with stainless tube, splitter cassette, ABS splitter or LGX metal box or even in splice closures, ODF tray, or fiber distribution boxes. If 1×4 or higher fiber coupling, can only pack by ABS module, and 3*3 can only be a single window, 1*3 dual window fibre coupler can only be made in ABS modules.

All fiber optic couplers can add connectors SC LC FC ST, polish mode UPC APC PC, the optical wavelength can be customized within 850nm 1310nm, 1310nm 1550nm 1490nm. If not specify, corning SMF-28e G.657A1 single mode fiber for single mode fiber coupling efficiency.

Meanwhile, the most popular fiber optic cable coupler are 1×2 coupler,  the fiber coupling can be customized from 1/99, 2/98, … 10/90, 15/95, 20/80, 25/75, 30/70, 35/65, 40/60, 50/50.

Steel Tube FBT Splitter

Steel tube fbt splitter are mainly 1×2 fiber couplers and 2×2 fiber coupler, the steel tube are made of stainless steel material, and 3 different sizes:

• Type D-￠3mm x 45mm;
• Type E-￠3mm x 54mm;
• Type F-￠3mm x 60mm.

The input and output fiber optic pigtail can be 250um bare fiber or 900um loose tube. Custom connectors, fiber type and length, loose tube color.

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Cassette FBT Coupler

Casstte FBT copuler are bigger size than steel tube 10*20*90mm, suitable for 1×2 fiber optic coupler and 2×2 coupler, the input and output fiber optic cable can be 2.0mm 3.0mm or 900um loose tube indoor soft simplex cables with or without connectors. Custom cable type, cable color, fiber type or connectors.

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ABS Splitter FBT

ABS module splitters for fiber optic coupler are the largest 10*80*100mm, suitable for 1×3, 1×4 1×5 1×6 1×8 or more channels, the input and output cable can be 0.9mm, 2.0mm, 3.0mm simplex indoor fiber optic cable, with or without connectors. Fiber length, fiber type, cable color can be custom. There is number mark on the module itself to identify inport and outport.

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FBT Coupler Quality Control

Blister Box Individual Pack

Every 1 or 2pcs in a blister box, with test report, good protection to product during long transporation.

Test Report

Each fiber coupler configurate with test report, which indicate the insertion loss, PDL, and other optical parameters.

Block For Output Pigtails

There will be block seal for output pigtails, to keep all in place, with glue to fix it.

Block For Input Pigtail

There will be block seal for output pigtails, to keep all in place, with glue to fix it. Perfect size, good protection, stable performance.

“IN” for Input Pigtail

Input side of coupler will have number ring “IN” to distinguish with output, and loose tube color is white if customer not specify. Other color is available.

Mark of Split Ratio

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Optical Fiber Coupling Efficiency

FBT Splitter Loss Chart

FBT splitter advantage & disadvantages

Advantage

The taper coupler has a history and experience of over 20 years, and many equipment and processes only need to be used, with development costs only a few tens or even a few hundred times that of PLC;

The raw materials only include easily obtainable quartz substrates, optical fibers, heat shrink tubes, stainless steel tubes, and a small amount of adhesive, totaling no more than one dollar And the investment depreciation cost of machines and instruments is even lower, The cost of low channel like 1×2, 1×4 splitter is low;

The splitting ratio can be monitored in real-time as needed, and unequal splitting splitters can be made.

Disadvantages

Loss is sensitive to the wavelength, and devices are generally selected based on the wavelength. This is a fatal flaw in the process of using the three networks in one, as the optical signals transmitted in the three networks in one include multiple wavelength signals such as 1310nm, 1490nm, 1550nm, etc;

Poor uniformity (refers to the change of insertion loss at each output that evenly distributes light). The nominal maximum difference of 1X4 is about 1.5dB, 1×8 is even greater. Coupler cannot ensure uniform light splitting and may affect the overall transmission distance. Currently, mature cone pulling processes can only pull less than 1×4 at a time, more outputs above 4 will use multiple 1×2 couplers and then pack as a whole in a box;

The insertion loss varies greatly with temperature (TDL) (Insertion loss refers to the ratio of the output optical power of a port to the input optical power). Insertion loss is composed of two parts: one is additional loss, and the other is spectral ratio factor; The insertion loss varies depending on the spectral ratio of the device, therefore; There are no specific provisions in the standard;

Multiplex splitter such as 1×16, 1×32, the volume is relatively large, and the reliability will also be reduced, resulting in limited installation space.

The FBT splitter only supports 4 wavelengths: 850nm, 1310nm, 1490nm, and 1550nm, which makes it unable to operate at other wavelengths.

Frequently Asked Questions