FBT Coupler and PLC splitter Tech
Planar Lightwave Circuit (PLC) splitter, PLC splitters are used to distribute or combine optical signals. It is based on planar lightwave circuit technology and provides a low cost light distribution solution with small form factor and high reliability. Planar lightwave circuit (PLC) splitter is a type of optical power management device that is fabricated using silica optical waveguide technology to distribute optical signals from Central Office (CO) to multiple premise locations.
Fused biconical taper,this is traditional technology to weld several fiber together from side of the fiber.
2. Comparison between FBT and PLC.
SpliSplit Ratio (Max): 1*64 splits
Eveness: Can split light evenly
Size: Compact size
Split Ratio: 1*8 splits
Eveness: Eveness is not very precise
Size: Big size for multi splits
TDL (Temperature Dependent loss)
Due to the manufacturing process and to the sensitivity of the fused region and of the splices integrated in the device, Fused coupler manufacturers have to specify also the TDL value. for a 1×2 Fused coupler, a typical value is +/10.15dB for a temperature range from -5 to +75 centigrade . At the first sight, it could look good, but we have here again to take into account the cascading effect. To make the comparison with 1×8 PLC splitter we have to multiply 0.15 by 3 (3 1×2 for each arm) to finally obtain 0.45dB.
PLC splitter works from -40 to 85 centigrade with a typical TDL of out +/- 0.25dB (-5 to 75 centigrade:+/-0.15dB)
Please note that this TDL effect is already included in the Max. insertion loss specifications available on data sheets.
PDL (Polarization dependent loss)
An lon-exchange PLC splitter shows a PDL much less than 0.2 dB independently from the split-ratio. A 1×2 fused coupler PDL ranges from 0.1 to 0.15dB.Also in this case, we have to cascade discrete 1*2 Fused coupler to obtain the desired split-ratio, Then also PDL will be increased.
A 1×8 fused coupler will show up to 0.45dB PDL, what is more than the double of a 1×8 PLC splitter.
As previously explained, to fabricate 1×8 fused coupler, you need 7discrete 1×2 couplers and 6 splices. The risk of failure of a device, normally calculated by parameter called FIT(failure in time), is typically low for a single 1×2 fused coupler, but in the case of a 1×8 fuse fused coupler ,it has to be at lease multiplied by 7 and in addition to add the risk associated to the massive presence of splices in the circuits. As everybody knows, a splice is a potential failure point in a system to be minimized a s much as possible.At the contrary, a PLC splitter knows only 2 critical points: input and output
People take advantage of fiber optic splitter that will send or simply combine optical signals in a good many products, which include FTTH solution, or anything else. Once in a while contain a challenge: Will certainly Make the most of PLC Splitter or FBT Coupler?
When you undertake compare, came across undertake compare meant for tools within the same exact split-ratio.
Insertion loss and uniformity vs. wavelength
The figure 1 shows the insertion loss plot of a standard 1×8 PLC splitter from 1250 to 1650 nm. You can observe the maximum insertion loss including the water-peak in E band region(1360 to 1460 nm) and also the excellent uniformity out of this plot.
Typical value is 9.8dB for insertion loss and 0.5dB for uniformity.
A 1×2 fused coupler insertion loss plot is showed in the figure 2.if you analyze the operating wavelength range from 1250 to 1650 nm as for PLC splitter you will still find an overall good performance level. But that’s a single 1×2 fused coupler, so you are not comparing the same devices.
The 3rd plot represents the insertion loss spectral behavior for 1×8 fused coupler. To fabricate a 1×8 fused coupler device each arm have to be manufactured using 3 cascaded (spliced) 1×2 couplers. it means that the “worst” arm could show 10.8dB insertion loss max and the uniformity will be 3dB.
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