Average Power Penalty Research Articles

An experimental diffuse optical wireless link employing DPIM

The paper presents the design for an experimental indoor optical wireless (OW) diffuse link using the digital pulse interval modulation (DPIM) scheme. Complete system implementation and procedure for carrying out the measurement are given. The system performance in the presence of artificial ambient light (AAL) sources is given. A high pass filter (HPF) with a cut-on frequency of 50 kHz is found to be sufficient to reject the interference signal from all AAL sources with the exception of the high-frequency (HF) fluorescent lamp (FL). Optical filtering reduces the average optical power penalty by 1 dB and 0.2 dB for the low-frequency (LF) FL, and the daylight. For the lowest error rate, the optimum HPF cut-on frequency in the presence of the HF-FL is found to be 884 kHz. The incandescent bulb introduces the largest average optical power penalty of 2.3 dB.

Data Parallelization by Optical MIMO Transmission Over Multimode Fiber With Intermodal Coupling

Data parallelization by means of optical multiple-input multiple-output (MIMO) transmission over dispersive multimode fiber (MMF), with a high degree of modal coupling but not accounting for intermodal dispersion, is investigated by developing an analytical model for direct detection of MMF MIMO frequency-flat transmission with mutually incoherent sources. The MIMO channel performance is derived in terms of a new formulation of a channel matrix for modal group powers accounting, for the first time, for modal coupling. For fixed aggregate signaling rate and power budget, for uncoded bit streams, increasing the number of output detectors improves the bit error ratio (BER)-similarly to wireless MIMO. However, contrary to wireless MIMO, increasing the number of input ports actually yields a BER penalty, which is traceable to the quadratic nature of photodetection. We finally establish the feasibility of enhancing the aggregate bit rate using multiple inputs in the case that the individual single-input-single-output channels are band limited, e.g., given optical data sources each at 2 Gb/s, it is possible to attain a 12-Gb/s signaling rate over several hundreds of meters of MMF at 10-10 BER, by utilizing six such inputs into the MIMO system, while incurring just a small average power penalty of approximately 2 dB/channel. The current model assumes strong intermodal coupling and neglects ISI influence over distances of up to hundreds of meters at gigabit rates, providing a first step in the optical MIMO analysis. On the other hand, similar scenario is practically met for shorter distances (up to 100 m) for the novel types of plastic optical fibers.

Compact 160-Gb/s Add–Drop Multiplexer With a 40-Gb/s Base Rate Using Electroabsorption Modulators

We report on the first 40-Gb/s-based 160-Gb/s add-drop multiplexer (ADM) using a pair of standing-wave enhanced electroabsorption modulator (EAM). Direct time-domain switching is performed without interferometers or optical control pulses as required by previously reported approaches, which indicates great advantages in compactness for the EAM-based ADM. Also, a 40-Gb/s base rate is attractive in realizing a more efficient 160-Gb/s system. Error-free operation for all channels is obtained with an average power penalty as low as 1 dB.

80 Gbit/s single wavelength soliton transmissionover 172 km installed fibre

Single wavelength soliton transmission at 80 Gbit/s has successfully been performed over 172 km installed fiber. Soliton data with pulse widths of 4.5 ps was transmitted with an average power penalty for all eight time-division-multiplexed channels of 1.3 dB.

Fully connectorized high-speed Ti:LiNbO3switch/modulator for time-division multiplexing and data encoding

We demonstrate a fully connectorized and packaged, 2×1 high-speed Ti:LiNbO 3 directional coupler switch suitable for both optical time-division multiplexing/demultiplexing and modulation at a 1.3- μm wavelength. The device has an intrinsic switching time of 60 ps and a small-signal 50-percent optical modulation depth bandwidth of 6 GHz. We have actively multiplexed two optical pulse streams with output non-return-to-zero (NRZ) center-to-center bit spacings of less than 100 ps, while incurring an average optical power penalty of only 0.5 dB. In addition, we have used this switch as a modulator to encode a pseudo-random data stream at 2-Gbit/s NRZ without degradation of the eye pattern or the semiconductor laser source spectrum.