Shen Zhen ZJY Patent City Co. Ltd. - POF,plastic optical fiber,GEPON

Author：Olaf Ziemann，Hans Poisel，Sebastian Randel，Jeffrey Lee
                                                                     
                                           Ya-Hui Wang    Translation

Abstract: Polymer Optical fibers combine the advantages of an optical communication medium with the availability of low cost components and extremely easy installation. After the introduction of POF in car networks the use in building networks will be the next big market. Inter device data links and sensor networks are additional potential fields of application. Improved active components and the use of efficient coding schemes will open new possibilities for optical data communication in a distance range between centimeters and several 100 meters.
OICS codes: (060.2330) Fiber optics communications (230.0250) Optoelectronics

1. Introduction
The interest in the use Polymer Optical Fibers for data communication and sensors is fast growing in
these years. Several reason are responsible for this development. One of the most important reasons is the increasing number of broadband access lines and the introduction of real time video services in high quality. This paper will summarize the recent technical developments and will show the improvements in
the use of the transmission capacity of the POF.
A second part is dedicated to market and standardization issues. The main difficulty is to find the
balance between cost effective products and the best technical solution. Our proposal is the mass market
introduction of PMMA-SIPOF systems, followed by next generation high bandwidth POF systems.

2. The evolution of optical networks
Not too many people know, that glass and polymer optical fibers have been developed at the same time at the end of the 60’s. Since that time, we could see an impressive development of glass fiber transmission systems with the current capacity of 25 Tbit/s (OFC’2007) and nearly unlimited transmission distances. Polymer Optical Fibers on the other hand side have been a niche technology for decades.  POF offer extremely easy handling and the use of low cost components, but POF systems are limited in distance and speed. The increasing demand for high speed, low cost connections in short distance transmission systems open new application areas for POF. Our vision for the use of these systems is
demonstrated in Fig. 1.
 

        At the present time. POF is well established in automation and car networks. The use of POF in home networks has a several orders of magnitude higher market potential. Divers manufacturers offer links for less than 100 € with fast Ethernet capacity. Some Gbit/s transceivers are available since some weeks now. The development of better active components (low capacity photo diodes, VCSEL and fast LED) and improved modulation schemes (DMT, multi level coding) offer higher speed systems at low
prices.

3. Shall be the “Standard-POF” the standard POF ?
Several index profiles and core materials have been developed and used for POF in the last decade
(see [1] and [2] for details). The best known fiber is the 1 mm core diameter PMMA based POF with step index profile and a numerical aperture of 0.50, frequently called standard POF. This POF type is used in car networks, in industrial bus systems and in most of the existing Fast Ethernet home networking products. Parameters of different POF according to the present international standard are summarized in Tab. 1.

Table 1: Specification of POF according to IEC 60793-2-40 (A4b and A4c with smaller diameter)

        It must be clarified, that class A4a covers >90% of all applications. All existing car networks (MOST, Bytefligh) and nearly all systems for automation and home networks are based on this fiber type. Sometimes the A4d fiber is recommended for links between 50 m and 100 m. The different multi core, multi step index and graded index PMMA based fibers have shown the usability for higher data rates and show some more advantages, like improved bending properties. Nevertheless, the success of all these
fibers on the market is still limited. This is also true for the different classes of GI-POF based on perfluorinated material, even if these fibers proved there potential for 10 Gbit/s over 200 m. All POF classes over the A4a fiber are relatively expensive - mainly caused by the small production volume. One
of the most important questions is now the choice of the right fiber for the next years. The ollowing table compares three possible strategies:

Table 2: comparison of strategies for the POF
market in the next future 

       The question, if the main effort to bring the POF into mass market applications shall be concentrated on the simple tandard POF or on one of the higher classes POF has been discussed seriously over the last time. The decision of a erman group, representing a large number of component manufacturers in cooperation with three Japanese fiber anufacturers can be summarized as follow:

(1) A new class A4a* “communication grade” standard POF will be defined with improved parameters, more riented on market available fibers (160 dB/km loss at 650 nm, NA: 0.48 ± 0.02, bandwidth: 40 MHz·100m)
(2) Multi core and GI-POF can be used as alternatives, if they are downwards compatible to the standard POF.
(3)  The PF-GI-POF is recommended for higher distances and for the transmission of CATV signals.
This will allow the use of all the different available LED based Fast Ethernet products as well at the connector free nstallation in the customers apartment. The next very important question will be answered in the next section: Is his fiber ready for next generation Gbit/s data transmission ?

4. What is the real capacity of the POF
        In the present discussion about the capacity of POF, the max. bit rate will be calculated by simple doubling the 3 dB andwidth (typically measured under EMD conditions). Figure 2 shows the length dependent capacity for the andwidth estimation of 10 MHz·100m (A4a) and 40 MHz·100m (A4*). The different dots represent laboratory
experiments of the POF-AC and Siemens Munich ([1], [5]). 
                         
       In fact, the data transmission of 1 Gbit/s over several 10 m of the SI-POF is possible with very simple passive equalizing. Using DMT (Discrete Multi Tone) modulation, more that 1 Gbit/s over 100 m have been realized with red lasers and about 1.4 Gbit/s with a blue LED over short distance. In the presentation we will demonstrate the latest results.

5. Summary
        In order to bring the POF into mass market applications as fast and easy as possible, we propose the use of standard 1 mm POF (A4a* class). The main application is the use for Fast Ethernet connections in home networks (e.g. for IPTV). We have demonstrated, that this fiber allow 1 Gbit/s over 25 m to 50 m easily, even with using LED transmitters. If one combines the use of very low cost (and low power operating) LED sources and the extremely easy handling
(small bending radius, mechanical robustness) and installation of large core fibers, the POF is a perfect candidate for interconnection solutions too (e.g. inside of devices, on board and chip-to-chip connections).

References
[1] O. Ziemann, W. Daum, P. E. Zamzow: “POF Handbuch, Optische Kurzstrecken- Übertragungssysteme”, Springer Sept.2007, English version “POF Handbook - Optical Short Range Transmission Systems” announced for Mai 2008
[2] O. Ziemann. H. Poisel: “Short Distance Optical Connections for Home Networks, Sensing and Mobile Systems”, OFC, 24.-27.03.2007, Anaheim USA, invited paper
[3] S. C. J. Lee, A. M. J. Koonen, S. Randel, J. Vinogradov, O. Ziemann, B. Offenbeck: “10 Gbit/s over large diameter Polymer Optical Fibers using Discrete Multitone Modulation”, POF’2007, Torino, 10.-12.09.2007, pp. 71-74
[4] S. Schöllmann, C. Wree, A. Joshi, W. Rosenkranz: “First Experimental Transmission over 50 m GI-POF at 40 Gb/s for Variable Launching”, ECOC’2007, Berlin post deadline paper PD 3.7
[5] F. Breyer, S. C .J. Lee, S. Randel, N. Hanik, “1.25 Gbit/s Transmission over up to 100 m Standard 1 mm Step-Index Polymer Optical Fibre using FFE or DFE Equalisation schemes”, ECOC 2007, Berlin, paper 9.6.6