## 2 Results and Discussion
### Baseband Data Transmission over PFGI-POF at 10 Gbps  
A preliminary study dealing with lower data rate (1.25 Gbps) has been performed according to the Gigabit Ethernet standard (GbE). The transmission has been demonstrated through the large core diameter Lucina fiber at 850 nm (length: 100 m up to 300 m). The Bit Error Rate (BER) has been measured as a function of the received optical power to exhibit the power dispersion penalties of the PFGI-POF at 1.25 Gbps (Figure 13). The power dispersion penalties are close to 1.2 dB for 300 m length. Figure 12: Optical losses measurement owing to a lateral offset. Figure 13: BER measurement as a function of the received optical power. In order to vary the optical power inside the PFGI-POF link, a tailormade optical attenuator (Figure 14) has been designed: it is composed of two PFGI-POF patchcords, two graded index (GRIN) lenses and a disk with adjustable optical density. The insertion loss of the designed attenuator is close to \(-1.5\) dB at 850 nm. The eye diagram of the fiber link is depicted in Figure 15 and clearly shows the bandwidth capacities of the PFGI-POF. In order to study the evolution of the BER inside the eye diagram, a isoBER plot measurement has been carried out and is reported in Figure 15. The preliminary study has been done in order to understand the behavior of the PFGI-POF, to design a POF based optical attenuator and to exhibit the performances of such a fiber. The 10 GbE transmission over a PFGI-POF has been proposed firstly by [PERSON] _et al._[20]. A fiber transmission at 11 Gbps occurring at 1,300 nm over 100 m has been reported. This preliminary reported work at a higher data rate has been performed with a 1,300 nm [PERSON] laser and coupling optics which are not suited for a low cost 10 Gbps optical network. In [18], it has been proposed to investigate the use of conventional low cost devices such as VCSEL (Vertical Cavity Surface Emitting Laser) and PIN (Positive-Intrinsic-Negative) photodiodes with plastic fiber in order to have a pragmatic approach to the future high speed optical network. The Phyworks technology [21], which consists of using Electronic Dispersion Compensation devices (EDC) placed at the electrical output of a conventional photoreceiver (here, a GaAs photodiode), has been used. The EDC technology overcomes the modal dispersion of the multimode fibers either in glass or polymer. Phyworks Company wants to produce 10 Gbps TX/RX module including VCSEL TOSA (Transceiver Optical SubAssembly) and driver for the TX part and photodiode ROSA (Receiver Optical SubAssembly), EDC and transimpedance amplifier (TIA) chips for the RX part with a target price of less than USD 200 per module. The coupling pair EDC/TIA cost should be around USD 55 (less expensive devices to the ones used in [20]). EDC technology is a cost effective solution  
Figure 14: Description of the designed attenuator. to combat the intermodal dispersion inherent to the optical link based on the multimode fiber. The Phyworks serial EDC replaces the existing Clock Data Recovery (CDR) of a classical 10 Gigabit Small Form Factor Pluggable Module (XFP). The transmission of a 10.3125 Gbps baseband signal over the four PFGI-POF (GigaPOF50-SR, GigaPOF62-SR, GigaPOF120-SR and Lucina) has been performed (Figure 16). As mentioned previously, the study done by [PERSON] _et al._[20] has been achieved at 1,300 nm and with a 130 \(\upmu\)m core diameter PFGI-POF. The restricted mode launch conditions of the PFGI-POF have been simulated with a single mode fiber coupled to the 1,300 nm laser in order to decrease intermodal dispersion effects. Moreover, in order not to induce mode filtering at the receiver, and to reduce the  
Figure 15: **(a)** Eye diagram of the 1.25 Gbps transmission over 300 m of PFGI-POF.