Lukasz Maksymiuk

Binary-Phase Spatial Light Filters for Mode-Selective Excitation of Multimode Fibers

In this paper, spatial light modulation is proposed to increase the transmission capacity of graded-index multimode fibers. In the method, selected linearly polarized eigenmodes of the fiber are excited using simple binary-phase spatial filters. Numerical results indicate that the selectivity of the method is very high, also for fibers with perturbed profiles. The excess attenuation of the method is very low. In the experiment, a threefold increase of fiber bandwidth for several filters is obtained.

Instability of the Multimode Fiber Frequency Response Beyond the Baseband for Coherent Sources

Fluctuations of the multimode fiber (MMF) frequency response beyond the baseband are observed experimentally when highly coherent light sources are used. This behavior is caused by the variation of the mode group powers caused by the relative modal phase fluctuation combined with spatial filtering at elements such as nonideal connectors. The observed effect may have vital influence on subcarrier multiplexing systems operation outside the baseband of the MMF. The effect is investigated both theoretically and experimentally.

Increasing multimode fiber transmission capacity by mode selective spatial light phase modulation

We propose spatial light modulation with binary phase filters to increase the transmission bandwidth of multimode fibers. In the experiment more than 300 % of bandwidth enhancement is obtained.

Experimental Comparison of PAM, CAP, and DMT Modulations in Phosphorescent White LED Transmission Link

In the paper, an experimental comparison of pulse amplitude, carrierless amplitude-phase, and discrete multitone modulations is carried in a visible light communications link employing white phosphorescent light-emitting diode (LED) as a transmitter. By changing the modulation index, the influence of LED nonlinearity on the performance is studied. The results indicate similar performance of pulse-amplitude modulation (PAM) and carrier-less amplitude-phase (CAP) (with a slight advantage of the former) and substantially worse performance of DMT.

A 2 and 3 channel mode group diversity multiplexing transmission over graded and step index multimode fibers

In this paper, operation of a cost-effective mode group diversity multiplexing system allowing 3 channel operation is demonstrated. Two different multiplexing/demultiplexing techniques are presented.

Transmission Beyond 100 Mbit/s Using LED Both as a Transmitter and Receiver

In this letter, the experimental operation of a wireless transmission link employing identical LEDs both as transmitter and receiver is demonstrated. The transmitted signal is a simple, two-level pulse amplitude modulation. Digital equalization at the receiver is applied to overcome the bandwidth limitation of the link. Transmission throughput exceeding 100 Mbit/s is reported, even if the receiving red LED operates in the photovoltaic mode.

Substantial OBI Noise Reduction in MM Fiber Network

Optical beat interference is one of the major problems impairing upstream transmission in passive optical networks. In this letter, a theoretical study indicates that if single mode fibers are replaced with multimode fibers, the interference is reduced at least by the factor of N, where N is the number of modes propagating. In the experiment carried with two types of lasers, a reduction of beating noise ~10 dB is observed. Even greater reduction is expected in the first transmission window.

Successful IEEE 802.11n 2-channel MIMO transmission over standard graded index multimode fiber in passband

We present a successful transmission of an IEEE 802.11n 2×2 Multiple Input - Multiple Output radio signal over standard graded index multimode fiber at several kilometers length. For the first time commercially available Access Points were used in the MIMO over multimode fiber experiment. Transmission was carried above the baseband of the multimode fiber (in passband), the electrical carrier was at 2.4 GHz. The experiment indicated an increase in the bitrates in the MIMO mode versus single channel operation. It has to be emphasized we have measured a real payload bitrate of the system.

Multimode Fiber Passive Optical Network for IEEE 802.11 Signal Distribution

In this paper, we present a novel concept of the IEEE 802.11n signal distribution over a multimode fiber passive optical network. In the study we provide a theory on the sources of potential interference in such a network, namely optical beat interference and modal noise, and ways to mitigate them. We demonstrate a passive optical distribution network deployed in a real environment of the facultys building. Our deployment utilizes custom designed remote antenna units. In the paper, we provide a series of network throughput measurements in different scenarios. These results confirm the correctness of our solution and show its excellent performance. The latter proves the network to be optically transparent. The distribution network does not downgrade the transmission rate when compared to the sole radio access point, and in addition it significantly increases the overall radio coverage.

Measurements of multimode fiber PON bandwidth

Employment of MM PON appears to be natural for short-range application such as intra-office or home networks. We have presented the results of the measurements of MM fiber PONs frequency responses in various configurations.