A Novel and Economic Way to Fiber-to-the-Home (FTTH)

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A Novel and Economic Way to Fiber-to-the-Home

(FTTH)

Don Liu Shu-Sen Tieh

Division R&D

Coretech Optical Co. Ltd.

don.liu@coretech-optical.com ss.tien@coretech-optical.com

Hsi-Chien Liu Hsiang-Chen Hsu

Department of Mechanical and Automation Engineering, I-Shou University

show_coolboy@yahoo.com.tw hchsu@isu.edu.tw

Abstract―In the last mile of Optical Access Network,

high fiber-to-the-home (FTTH) construction cost per sub-scriber has always been a concern for the Network Oper-ators. In order to cost down the fiber and transceiver deployment, PONs are developed to replace Active P2P Network Access. Also the splitter placement problems are issued that make efforts to reduce fiber and splitters deployment cost. Cost down the Optical Components in PONs is one of the successful elements for building the business of FTTH. For an example, instead of tradition-al method, a 1x12 splitter module which is cascaded by one piece of 1x2 (67%:33% power ratio, 2.6dB:6.2dB IL) and 10 pieces of 1x2 (50%:50% power ratio, 3.7dB IL) splitters, the IL of module is 2.6+3.7x3=13.7dB; an eco-nomical 1x12 splitter module could be cascaded just by one piece of 1x3 (IL: 5.4 dB) and 3 pieces of 1x4 (IL: 7.2dB), the IL of module will be 5.4+7.2=12.6dB, 1.1dB less than the former. In the case of 1x36, an economic one is cascaded by 4 pieces of 1x3 and 9 pieces of 1x4 splitters (IL: 18dB) to replace the traditional one which is cascaded by 35 pieces of 1x2 splitters (IL: 19.9dB). Another case of 2x24, an economic one is cascaded by 1 piece of 2x2, 2 pieces of 1x3 and 6 pieces of 1x4 splitters (IL: 16.3dB) to replace the traditional one which is cas-caded by 1 pieces of 2x2 and 22 piece of 1x2 splitters (IL: 17.4dB). In conclusion, bundle with less Insertion Loss, the economical multi-output splitter module can be suc-cessfully built up by this novel fiber coupler manufactur-ing apparatus and method.

Index Terms―FTTH, PON, optical splitter, Insertion

loss IL, topology of cascade.

I. INTRODUCTION

In the last mile of Optical Access Network, high FTTH construction cost per subscriber has always been a concern for the Network Operators. In order to cost down the fiber and transceiver deployment, PONs (Passive Optical Networks) are developed to

replace Active P2P (Point to Point) Network Access. Also the splitter placement problems are issued that make efforts to reduce fiber and splitters deploy-ment cost. Cost down the Optical Components in PONs is one of the successful elements for building the business of FTTH.

1x32 and 1x64 PLC (Planar Light-wave-guide Circuit) splitters could be specified for EPON (Ethernet PON) and GPON (Giga-bit PON), nev-ertheless those are not able to distribute optical power unevenly. Generally, a multi-port output splitter module is built up by cascading a group of 1x2 optical splitters. The more numbers of splitters we need the more Insertion Loss (IL) will take place. It is even harder to build such as 1x12, 2x24 and 1x36 splitters whose numbers of output ports are not equal to power series of 2. By the novel US patented Fused Fiber Coupling Machine in 2007 [1], monolithic 1x2, 1x3, 1x4 and 1x5 optical splitters were made, as well as a number of suc-cessful stories in Europe and Taiwan FTTH dep-loyment cases came true.

II. TOPOLOGY of OPTICAL SPLITTER CASCADING Suppose there is a 1xN optical splitter module with 1 input port and N output ports in the optical cable node. The splitter module is cascaded by 1xA 1xB 1xC and 1xD splitter elements. In addition, the priority of splitter elements selection is :

1xA : the fist, 1xB : the second 1xC : the third 1xD : the last.

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and N = (Aa) (Bb) (Cc) (Dd)

then it is able to be proved by summation of power series that the number of splitter elements in are :

1xA : N(A) = (Aa -1) (Bb) (Cc) (Dd) / (A -1) 1xB : N(B) = (Bb-1) (Cc) (Dd) / (B -1) 1xC : N(C) = (Cc-1) (Dd) / (C -1) 1xD : N(D) = (Dd-1) / (D -1)

Practically, the monolithic 1x2, 1x3, 1x4 and 1x5 splitter elements can be made by the novel US pa-tented Fused Fiber Coupling Machine as well as considering the optical performance and economic cost the priority of selection are 1x4, 1x5, 1x3 and 1x2 in order.

III. TRADITIONAL SPLITTER MODULE CASCADED

by 1X2 COMPONENTS

Traditionally, a piece of 1x (2n) optical splitter can be cascaded by (2n-1) pieces of 1x2 splitter as shown in Fig.3-1 to Fig.3-4. For example, a piece of 1x8 splitter is cascaded by 7 pieces of 1x2 split-ter; a piece of 1x16 splitter is cascaded by 15 pieces of 1x2 splitter; a piece of 1x32 splitter is cascaded by 31 pieces of 1x2 splitter; a piece of 1x64 splitter is cascaded by 63 pieces of 1x2 splitter. Neverthe-less, a piece of 1xN splitter is not able to be cas-caded by 1x2 splitter only, while N (the number of output ports) is not equal to the power series of two.

Fig.3-1 1x8 splitter by 1x2 cascading (No. of 1x2 splitter in used:1+2+4=7).

Fig.3-2 1x16 splitter by 1x2 cascading (No. of 1x2 splitter in used:1+2+4+8=15).

Fig.3-3 1x32 splitter by 1x2 cascading (No. of 1x2 splitter in used:1+2+4+8+16=31).

Fig.3-4 1x64 splitter by 1x2 cascading (No. of 1x2 splitter in used:1+2+4+8+16+32=63).

IV. A NOVEL AND ECONOMIC WAY OF C ASCAD-ING SPLITTER MODULE

By the novel US patented Fused Fiber Coupling Machine [1] developed 2007, monolithic 1x2, 1x3, 1x4 and 1x5 optical splitters are able to be made. In case the number N of a 1xN optical splitter out-put-ports is a common multiple of 2; 3; 4 and 5, a novel economic cascading topology is implemented. Considering the factors of optical performance, re-liability and market price, the priority of choice we have made is 1x4, 1x5, 1x3 and then 1x2. It is found a piece of 1xN optical splitter can be eco-nomically cascaded by N(4) pieces of 1x4 splitter; N(5) pieces of 1x5 splitter; N(3) pieces of 1x3 splitter and N(2) pieces of 1x2 splitter; where

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1x2 1x3 1x3 1x2 1x4 1x4 1x2 1x5 1x5 1x3 1x3 1x3 1x3 1x2 1x3 1x3 1x3 N(5) = (5b -1) (3c)(2d) / (5-1) (2) N(3) = (3c -1) (2d) / (3-1) (3) N(2) = (2d -1) / (2-1) (4) N = (4a)(5b)(3c)(2d) (5)

According to ITU-T G.984 GPON Standard, the maximum number of splitter output ports is 64. For a piece of 1xN splitter module, while N is a com-mon multiple of 2,3,4,5 and less than 64, in Fig.4-1 to Fig.4-17, the topologies of 1x6, 1x8, 1x9, 1x10, 1x18, 1x20, 1x24, 1x25, 1x27, 1x30, 1x32, 1x36, 1x40, 1x45, 1x50, 1x54, 1x60 splitter cascading are shown.

Fig.4-1 An economic 1x6 splitter module.

From Fig.4-1, N = (40)(50)(31)(21) = 6. Comprising the bellow components: 1x4 : N(4) = (40 -1) (50)(31)(21) / (4-1) = 0 1x5 : N(5) = (50 -1) (31)(21) / (5-1) = 0 1x3 : N(3) = (31 -1) (21) / (3-1) = 2 1x2 : N(2) = (21 -1) / (2-1) = 1

From Fig.4-2, N= 8 = (41)(50)(30)(21) Comprising the bellow components: 1x4 : N(4) = (41 -1) (50)(30)(21) / (4-1) = 2

1x5 : N(5) = (50 -1) (30)(21) / (5-1) = 0 1x3 : N(3) = (30 -1) (21) / (3-1) = 0 1x2 : N(2) = (21 -1) / (2-1) = 1

From Fig.4-3, N= 9 = (40)(50)(32)(20) Comprising the bellow components: 1x4 : N(4) = (40 -1) (50)(32)(20) / (4-1) = 0 1x5 : N(5) = (50 -1) (32)(20) / (5-1) = 0 1x3 : N(3) = (32 -1) (20) / (3-1) = 4 1x2 : N(2) = (21 -1) / (2-1) = 1

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1x5 1x2 1x3 1x3 1x4 1x5 1x5 1x3 1x3 1x4

Fig.4-5 An economic 1x18 splitter module. From Fig.4-5, N= 18 = (40)(50)(32)(21)

Comprising the bellow components: 1x4 : N(4) = (40 -1) (50)(32)(21) / (4-1) = 0 1x5 : N(5) = (50 -1) (32)(21) / (5-1) = 0 1x3 : N(3) = (32 -1) (21) / (3-1) = 8 1x2 : N(2) = (21 -1) / (2-1) = 1

From Fig.4-9 N= 27 = (40)(50)(33)(20) Comprising the bellow components: 1x4 : N(4) = (40 -1) (50)(33)(20) / (4-1) = 0 1x5 : N(5) = (50 -1) (33)(20) / (5-1) = 0 1x3 : N(3) = (33 -1) (20) / (3-1) = 13

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1x2 1x3 1x3 1x5 1x2 1x4 1x4 1x4 1x3 1x3 1x4 1x2 1x5 1x5 1x4 1x2 : N(2) = (20 -1) / (2-1) = 0

From Fig.4-11, N= 32 = (42)(50)(30)(21) Comprising the bellow components:

1x4 : N(4) = (42 -1) (50)(30)(21) / (4-1) = 10 1x5 : N(5) = (50 -1) (30)(21) / (5-1) = 0 1x3 : N(3) = (30 -1) (21) / (3-1) = 0 1x2 : N(2) = (21 -1) / (2-1) = 1

From Fig.4-13, N= 40 = (41)(51)(30)(21) Comprising the bellow components:

1x4 : N(4) = (41 -1) (51)(30)(21) / (4-1) = 10 1x5 : N(5) = (51 -1) (30)(21) / (5-1) = 2

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1x3 1x3 1x5 1x2 1x5 1x5 1x5 1x3 : N(3) = (30 -1) (21) / (3-1) = 0 1x2 : N(2) = (21 -1) / (2-1) = 1

From Fig.4-15, N= 50 = (40)(52)(30)(21) Comprising the bellow components: 1x4 : N(4) = (40 -1) (52)(30)(21) / (4-1) = 0

1x5 : N(5) = (52 -1) (30)(21) / (5-1) = 12 1x3 : N(3) = (30 -1) (21) / (3-1) = 0 1x2 : N(2) = (21 -1) / (2-1) = 1

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Comprising the bellow components:

1x4 : N(4) = (41 -1) (51)(31)(20) / (4-1) = 15 1x5 : N(5) = (51 -1) (31)(20) / (5-1) = 3 1x3 : N(3) = (31 -1) (20) / (3-1) = 1 1x2 : N(2) = (20 -1) / (2-1) = 0

V. THREE SUCCESSFUL CASES

Case 1: 1x12 splitter module deployed in

Switzer-land

Fig. 5-1 Traditional 1x12 splitter module cascaded by 1x2 components.

As shown in Fig.5-1, normally one piece of unevenly 1x2 splitter, optical power ratio: 67% / 33%; insertion loss IL: 2.6 / 6.2 dB and 10 pieces of evenly 1x2 splitter, optical power ratio: 50% / 50%; IL: 3.7 dB are required to be cascaded. In total, the IL of this 1x12 splitter will be 13.7dB (2.6 + 3.7 × 3 = 13.7) and the market price is about 110 USD for reference.

Instead of above method, we used 1 piece of 1x3 (IL: 5.4 dB) and 3 pieces of 1x4 (IL: 7.2dB), totally 4 pieces of splitter elements to cascade a 1x12 splitter module as shown in Fig.4-2, in which the IL = 5.4 + 7.2 = 12.6 dB. It is found that 13.7 – 12.6 = 1.1 dB of optical power is saved. The market price for reference is 80 USD, cost-down more than 20%.

Fig. 5-2 An economic 1x12 splitter module.

Case 2: 1x36 splitter module deployed in the UK

Fig. 5-4 An economic 1x36 splitter module.

Case 3: 2x24 splitter module deployed in Taiwan.

1x2

1x2 67%

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Fig.5-3 shows a traditional 1x36 in this case, the 350 USD is cascaded by 35 pieces of 1x2 split-ters (IL: 2.6 + 6.2 + 3.7 x3 = 19.9dB) can be re-placed by a 260 USD economic one is cased by 4 pieces of 1x3 and 9 pieces of 1x4 splitters (IL: 5.4 + 5.4 + 7.2 = 18dB) as shown in Fig.5-4. 1.9dB of optical power is found and saves 90 USD.

In the case of 2x24, the 230 USD traditional is cascaded by 23 pieces of 1x2 splitters (IL: 2.6 + 3.7 x 3 = 17.4dB) as shown in Fig.4-5 is replaced by a 170 USD economic one is cased by 1 piece of 2x2, 2 pieces of 1x3 and 6 pieces of 1x4 splitters (IL: 3.7 + 5.4 + 7.2 = 16.3dB) as shown in Fig.5-6. 1.1dB of optical power is found and saves 60 USD.

Fig.5-6 An economic 2x24 splitter module. VI. RESULTS AND CONCLUSIONS

In conclusion, this novel topology by cascad-ing 1x4, 1x5, 1x3 and 1x2 splitter elements are more beneficial and effectively in both optical per-formance and cost compare to traditional model and PLC technology. Table 6.1 lists comparison.

Table 6.1 Comparison of splitter module cascade. Splitter Module Novel topology Traditional 1x2 cas-cading PLC tech-nology 1x12 module 1x4(3pcs) 1x3(1pcs) 1x2(10pcs; 50%/50%) 1x2(1pcs; 67%/33%) 1x16(1pcs) 4 ports idle Insertion Loss 12.6dB 13.7dB 13.8dB Price $80 $110 $140 1x36 module 1x4(9pcs) 1x3(4pcs) 1x2(31pcs; 50%/50%) 1x2(4pcs; 67%/33%) 1x64(1pcs) 28ports idle Insertion Loss 18dB 19.9dB 20.5dB Price $260 $350 $450 2x24 module 1x4(6pcs) 1x3(2pcs) 2x2(1pcs) 1x2(20pcs; 50%/50%) 1x2(2pcs; 67%/33%) 2x2(1pcs; 67%/33%) 2x32(2pcs) 8 ports idle Insertion Loss 16.3dB 17.4dB 17.2dB Price $170 $230 $210 REFERENCE

[1] “Optical fiber coupler and manufacturing appa-ratus and method thereof”; US Patent 7158712B2; Jan. 2, 2007