D. H. Thomas

Impairments of EDFA dynamic gain-fluctuations in packet-switched WDM optical transmissions

Sustained relaxation oscillations in a gain-clamped erbium-doped fiber amplifier can be generated depending on the traffic loading in packet-switched wavelength-division-multiplexed (WDM) optical networks. The effects are dependent on the channel wavelengths, on the packet power and width, as well as on the time delay between traveling packets. Depletions up to 1.6 dB can be generated when two or more WDM optical packets travel through the amplifier within a few oscillation periods of the amplifier.

Fully powered-over-fibre remote antenna unit

In order to achieve a reliable ROF system with centralized wavelength operation, it is essential to provide enough power for remote antenna unit without the need of copper wires or any kind of batteries. Moreover, to ensure a high quality full-duplex communication when heterodyne generation is employed to obtain the microwave signal, a carefully choice of the laser sources is very important. Despite no wires or batteries and no laser stability control were used, error free transmission was obtained in an original scheme.

Optical generation and detection of EHF microwave signals

The generation and detection of EHF microwave signals through the photomixing of two independent CW laser sources at commercial gallium-arsenide antennas is presented as a versatile technique for short range EHF communications. More than to eliminate further amplification before the irradiating antenna, the proposed technique is able to generate MMW signals at the EHF range with a maximum strength difference of 10 dB through the full range.

Design and characterization of a multiple-Bragg-gratings Fabry-Perot filter

In this paper we present the design and characterization of single and multiple Fabry-Perot filters (SFPF and MFPF, respectively). Through the correct design, which means a careful project of the fiber Bragg-gratings (FBG) and an accurate sizing of the parameters of the Fabry-Perots, it is possible to enhance the finesse of the filters. Once a good finesse has been achieved, such filters can be employed to generate a narrow microwave carrier, one of the most important requirements of modern radio-over-fiber (ROF) links.

Performance of Gain-Clamped EDFAs in Channel Routing and Packet Switched WDM Optical Transmissions

Some of the critical factors that affect the behaviour of an ail-optically stabilized EDFA were studied, but without differentiating disturbances caused by several network traffic cases. Traffic changes come from add or drop of WDM channels at any network node (WDM routing) or from random interarrival time of data in packet/burst switching transmissions. We evaluate the performance of two lasing wavelengths (above and below the C-band) in a ring-laser clamping configuration to reach minimal EDFA gain-fluctuation and high quality transmission, regardless the input signal condition in WDM routing and packet switched transmissions.

Optical Amplifier Hybrid Devices for S-Band Telecommunications--A Comparison

Amplifier hybrids coupling different amplifier types are characterized and evaluated for application in S-band telecommunications. Combinations including a fiber-optic parametric gain module are also studied for S-C/L band wavelength conversion.