Optimum index profile of the perfluorinated polymer-based GIpolymer optical fiber and its dispersion properties

The significant advantages in bandwidth and low material dispersion of perfluorinated (PF) polymer-based graded-index polymer optical fiber (GI POF) are theoretically and experimentally reported for the first time. It is confirmed that the low attenuation and low material dispersion of the PF polymer enables 1 Gb/s km and 10 Gb/s km transmission at 0.85-μm and 1.3-μm wavelengths, respectively. The PF polymer-based CI POF has very low material dispersion (0.0055 ns/nm·km at 0.85 μm), compared with those of the conventional PMMA-based POF and of multimode silica fiber (0.0084 ns/nm km at 0.85 μm). Since the PF polymer-based GI POF has low attenuation from the visible to near infrared region, not only the 0.65-μm wavelength which is in the low attenuation window of the PMMA-based GI POF, but other wavelengths such as 0.85-μm or 1.3-μm etc. can be adopted for the transmission wavelength. It is clarified in this paper that the wavelength dependence of the optimum index profile shape of the PF polymer-based GI POF is very small, compared to the optimum index profile shape of the silica-based multimode fiber. As a result, the PF polymer-based GI POF has greater tolerance in index profile variation for higher speed transmission than multimode silica fiber. The impulse response function of the PF polymer-based GI POF was accurately analyzed from the measured refractive index profile using a Wentzel, Kramers, Brillouin (WKB) numerical computation method. By considering all dispersion factors involving the profile dispersion, predicted bandwidth characteristic of the PF polymer-based GI POF agreed well with that experimentally measured     

Graded-index polymer optical fiber with high temperature and high humidity stability

It was clarified for the first time that the slight attenuation increment observed in the previous poly methyl methacrylate (PMMA)-dopant system graded-index polymer optical fiber (GI POF) we reported originated in the excess scattering loss induced by the aggregation of absorbed water into the POF. Although the PMMA material generally absorbs two weight% of water at maximum, the low attenuation of the conventional step-index (SI) POF whose core material is PMMA can be maintained at 70/spl deg/C, 80% relative humidity (RH) atmosphere because the absorbed water might be homogeneously dispersed without any aggregation in the core of POF. On the other hand, addition of dopant material having higher refractive index than that of PMMA is required to form the refractive index distribution in the GI POF, which decreases the amount of water absorption into polymer, because the dopant material is more hydrophobic than PMMA. Therefore, in spite of the small amount of absorbed water such as 0.5 wt.%, the absorbed water molecules can not be uniformly dispersed but must be aggregated to form heterogeneities in the refractive index of the polymer matrix. It was clarified that a dopant material that is as hydrophilic as PMMA was required to maintain the attenuation of the PMMA-dopant system GI POF under high temperature and high humidity atmosphere, and such a suitable dopant system GI POF was proposed.     

Modal bandwidth enhancement in a plastic optical fiber by W-refractive index profile

A plastic optical fiber (POF) having a W-shaped refractive index profile (W-shaped POF) was prepared for the first time that had a possibility to realize a higher bit rate transmission than those of the conventional silica-based multimode fiber and graded index (GI) POF links. Since the W-shaped POF has a valley of the refractive index at the boundary of the core and cladding of the conventional graded-index (GI) POF, the group delay of higher order modes is strongly influenced, and the modal dispersion in the GI POF is compensated. By comparing the propagating mode properties of the W-shaped POF with those of the GI POF, we clarified theoretically and experimentally that the index valley has a remarkable modal dispersion compensation effect.     

渐变折射率聚合物光纤的研究进展

介绍ＧＩＰＯＦ的带宽特性和应用,对比了ＳＩＰＯＦ、铜系电缆、玻璃系光纤和ＧＥＰＯＦ的传输特性,着重分析了ＧＩ ＰＯＦ的三种制备方法：普通共取法 面凝胶法和等离子态法,并综述了ＧＩ ＰＯＦ的研究的最新进展,指出了国内外ＧＩ ＰＯＦ的差距。     

Large-core, high-bandwidth polymer optical fiber for near infrareduse

High bandwidth (more than 500 MHz·km) graded-index polymer optical fiber (GI POF) for near infra-red use was successfully fabricated by using partially fluorinated acrylate polymer. Since only three carbon-hydrogen bonds exist in a monomer unit, an absorption loss due to the stretching vibration of the carbon-hydrogen bond was remarkably reduced compared with the conventional POF's. The attenuation of the GI POF at 780-nm wavelength was 135 dB/km, which is much lower than that of the PMMA core POF (800 dB/km). The fluorinated polymer-based GI POF is satisfying a significant segment of high-speed multimedia network applications     

Which is a more serious factor to the bandwidth of GI POF:differential mode attenuation or mode coupling?

It is clarified for the first time that the effect of the mode coupling on the bandwidth characteristic is very small in the graded-index polymer optical fiber (GI POF) compared with in the step-index (SI) POF. Although there have been several trials regarding the theoretical prediction of bandwidth characteristics of the GI POF, a disagreement between measured and estimated properties was observed. The origin of disagreement has been generally explained as the mode coupling effect. However, it is clarified in this paper that the effect of the differential mode attenuation is the dominant factor of disagreement between measured and predicted bandwidth characteristics, while the effect of the mode coupling is small. In order to clarify the reason why the calculated bandwidth characteristics of the GI POF show a disagreement with that measured, differential mode delay and differential mode attenuation were investigated. It was found that the highest order mode in the poly methyl methacrylate (PMMA) base GI POF attenuated 17 dB compared with the lowest order mode through 100-m transmission. By taking into account this differential mode attenuation, an excellent agreement is observed between calculated and measured results of both the bandwidth characteristics and group delay, in which no mode coupling was considered     

Analysis of graded-index polymer optical fiber link performance under fiber bending

Bending effects on bandwidth and loss of a graded-index polymer optical fiber (GI POF) were investigated, and those influences on the optical link performance were discussed simultaneously for the first time. The numerical apertures (NAs) of the GI POFs were deliberately varied from 0.154 to 0.292. A bending radius larger than 10 mm induced little mode coupling and little change in the bandwidth of the GI POF. A bending radius smaller than 10 mm caused degradation in the bandwidths of the higher NA GI POFs. On the other hand, in the lower NA GI POFs, even more severe bending could cause little change in their bandwidths. Thus, the lower NA GI POF seemed preferable in suppressing the bandwidth change. However, the higher NA GI POF exhibited the lower bending loss. The preferable NAs for both characteristics were completely opposite. Moreover, the bending loss under underfilled launch (UFL) could be lower than that under overfilled launch (OFL). On the other hand, the bending loss was equivalent to the bandwidth degradation in view of the link power penalty. Therefore, the bandwidth change and loss caused by the bending were the critical factors to optimize the optical link considering the link power budget. The high-NA GI POF with almost ideal refractive-index profile could provide stable high performance in overgigabit communication even under any bending conditions.     

High-Bandwidth Plastic Optical Fiber for Fiber to the Display

Novel photonics polymer devices for broadband technologies are described, focusing on the high-bandwidth graded-index plastic optical fiber (GI POF). Based on these photonics polymer device technologies, the concept of "Fiber to the Display" is proposed, where GI POF is directly distributed to display from main server in a building or house. Therefore, real-time face-to-face communication with high-definition-television quality becomes possible, which cannot be achieved by current technologies. The authors believe that new innovative concepts of broadband society in the 21st century will be realized by "the proposal from the material side."     

Analysis and Simulation of a Plastic Optical Fiber Access Network Based on OCDMA Technology

In this paper a plastic optical fiber (POF) access network based on optical code-division multiple access (OCDMA) technology is proposed. Recently, optical transmission using POF has received much attention due to its low weight, large core diameter, flexibility, and easy installation. Specially, its high bandwidth makes POF a very attractive candidate for a transmission media in an access network based on OCDMA technology. A conventional OCDMA system only allows a finite number of units to transmit and access simultaneously according to the number of channels which is restricted by BER. To resolve this problem a novel protocol is also proposed in this paper. The protocol can efficiently support variable-sized messages, and any new unit can join the network at any time without requiring network initialization. To implement the demonstration, each optical network unit is equipped with a fixed and a tunable optical encoder/decoder. The optical encoder/decoder employing planar holographic optical processors (HOPs) in this system may be of low fabrication cost. The network throughput and average delay using various system parameters has been investigated by numerical analysis and simulation experiments. It is shown that the dynamic control protocol in this POF access network based on OCDMA technology is valid and efficient.     

Mode-coupling control and new index profile of GI POF for restricted-launch condition in very-short-reach networks

This paper confirms that numerical aperture (NA) is a key factor in mode coupling [the energy transfer among propagating modes in multimode fibers (MMF)] and that providing a high NA is a viable solution to reduce mode coupling in graded-index plastic optical fibers (GI POFs). Furthermore, the authors propose a new refractive-index-profile design of GI POFs when only small mode groups are launched (restricted-launch condition), which is a combined profile with the index exponents lower and higher than optimum value for the core center and periphery, respectively. The advantage of the new index profile is investigated both experimentally and theoretically. Furthermore, it is verified that the high-bandwidth performance of GI POF with the new index profile under the restricted-launch condition is maintained even when statistical fiber bendings are added to the GI POF and when misalignment is caused at the optical coupling between the light source and the GI POF.     

聚合物光纤中的模式耦合及其对带宽的提高

光在聚合物光纤(POF)中传输时存在较强的模式耦合,由于模式耦合的影响,聚合物光纤的传输带宽得以提高。根据能流方程对阶跃型聚合物光纤光传输中的模式耦合进行了研究,从实验上测量了聚合物光纤的模式耦合系数,测量得到的模式耦合系数为7.61×10-4rad2/m。用测得的模式耦合系数对聚合物光纤中的模式耦合进行数值模拟,得到聚合物光纤的模式耦合长度约为20 m。由模式耦合长度可以得到聚合物光纤的真正带宽,其在150 m传输距离的带宽约为130 Mbit/s。为了验证这一结论,进行了125 Mbit/s.150 m的局域网(LAN)通信实验,通过对发射、接收波形及通信眼图的分析表明,由于模式耦合提高了聚合物光纤的传输带宽,使其可以在150 m的距离上进行百兆速率的通信传输。     

Thermally stable high-bandwidth graded-index polymer optical fiber

High-bandwidth poly (methyl methacrylate) PMMA base graded-index polymer optical fiber (GI POF) with high thermal stability is proposed. No distortion of bandwidth was observed even after more than 10000 hours aging at 85°C by selecting the large sized aromatic dopant which has a stable secondary interaction with PMMA matrix and maintains the high glass transition temperature (Tg) of the core of GI POF. The relationship between the heat-drawing condition from the GI preform to the fiber and the thermal stability in the attenuation was investigated. It was clarified that the length shrinkage of the fiber during the aging at high temperature caused large attenuation increase. On the other hand, the degree of shrinkage could be tightly controlled by changing the heat-drawing tension. It was confirmed that the GI POF drawn with optimized heat-drawing tension had no shrinkage of the fiber during aging at 70°C and no attenuation increase was observed     

基于聚合物光纤局域网系统的自由空间光通信

设计了与125 Mbps聚合物光纤局域网兼容的自由空间光通信系统,以实现楼宇间的数据通信,克服聚合物光纤传输距离较短的缺点.自由空间光通信包括发射和接收两个部分,发射部分由650 nm半导体激光器,驱动电路和准直扩束镜组成,接收部分由接收透镜和光电探测器组成.半导体激光器的调制发射功率为3 dBm,光电探测器的探测灵敏度为-27 dBm.分析了大气对光信号的衰减以及大气湍流造成的光斑抖动对通信的影响,记录了系统的信号传输波形和通信眼图.实验表明,自由空间光通信可以延长聚合物光纤局域网的通信距离,使其在实际工程中的应用更加灵活.     

Fabrication and properties of polymer optical fibers containingNd-chelate

Graded-index poly(methyl methacrylate) optical fibers (GI POF) containing a Nd-chelate have been fabricated. The absorption spectrum of the fiber exhibited several strong bands in the visible and infrared regions. We have observed infrared fluorescence (0.90, 1.06, and 1.3 μm) of the Nd³⁺ ion of the fiber at room temperature when it was pumped with an Ar⁺-pumped dye laser at 580 nm     

Low Cost Acrylic-Based 1×2 Asymmetric Plastic Optical Fiber Coupler for Optical Code Generating Devices

An optical code generating device has been developed based on a 1×2 asymmetric plastic optical fiber(POF) coupler.The code generating device provides a unique series of output power which are successively used as an optical code in a portable optical access-card system.The device utilizing a tap-off ratio(TOFR) technique based on a simple variation of the tap width of an asymmetric Y-branch splitter,allows various ratios of optical power to be generated.The POF coupler has been fabricated using low cost acr...     

First plastic optical fibre transmission experiment using 520 nmLEDs with intensity modulation/direct detection

A plastic optical fibre (POF) transmission experiment utilising green LEDs at a wavelength of 520 nm is reported. The transmission loss of the 100 m POF was 10 dB, which is considerably lower than the loss for red (660 nm) and blue (470 nm) LEDs. The receiver sensitivity at 30 Mbit/s was -20.8 dB at 10^-9 bit error rate, which suggests the possibility of a longer length signal transmission, 200 m or longer     

塑料光纤在高速局域网中的应用

文章主要叙述了塑料光纤(POF)的性能及其应用.随着网络技术及其各种服务的发展,短距离高速通信网络将是人们的一个追求目标,而POF因其具有性能好、传输速率高、价格低廉、连接方便等一系列优点将会成为高速局域网的首选传输介质.     

Plastic optical fiber technology for reliable home networking: overview and results of the eu project pof-all - [Topics in optical communications]

The rising performance of broadband connections for residential users, particularly in conjunction with fiber to the home, will present a new challenge for telecom operators in the short and medium terms: how to deliver the high bit rate digital signals with high quality-of-service to all consumer devices scattered inside the building of final users? Among the many different solutions for the home network, we review in this article the use of polymer optical fibers for short-reach and high-capacity optical communications for residential customer premises. POF is an easy-to-install, low-cost, and eye-safe solution for these networks, with the potential of being future-proof. In this article the state of the art in POF technology is presented by summarizing significant results achieved in the European project POF-ALL. Data transmission rates of more than 1 Gb/s over 50+ m and 100 Mb/s over 200+ m of standard step-index POF have been shown.     

A 4-wavelength optical multi/demultiplexer for WDM subscriber loop systems using analog baseband video transmission

This paper describes the design principles and performance of optical multi/demultiplexers (MUX/DEMUX's) in wavelength-division multiplexing (WDM) subscriber-loop systems over a 50- μm core diameter, graded-index (GI), multimode fiber, which employ analog baseband video transmission using laser diodes (LD's). In this WDM arrangement, requirements for MUX/DEMUX's are: 1) low insertion loss; 2) no signal degradation caused by optical interchannel crosstalk; 3) only a small amount of analog baseband signal degradation caused by the use of MUX/DEMUX; 4) a small size and simple structure capable of multiplexing three or four wavelengths; and 5) good stability. The newly developed 4-wavelength MUX/DEMUX satisfies the preceding requirements and is suitable for application to WDM subscriber-loop systems using analog baseband signals along with digital signals.     

塑料光纤数据通信网技术进展

系统论述了高速塑料光纤数据通信网的发展进展,给出一些有代表性的传输实验系统的实例。介绍了基于塑料光纤的数据传输系统的实际应用。讨论了塑料光纤通信系统的发展方向和前景。