This paper presents the performance of a proposed GaAs MESFET photodetector with wide drain-to-gate distances for improving the optical coupling efficiency in subcarrier optical transmission. Principle and design parameters of the proposed MESFET are described. Link gain, CNR, and BER, are experimentally investigated as functions of the drain-to-gate distance. It is experimentally found that the proposed MESFET improves the link gain by 8.5 dB compared to the conventional structure at the subcarrier frequency of 140 MHz. Discussions are also included compared to PIN-PD.

This paper overviews fiber-oriented wireless communication systems, particularly in the area of microcell systems. The benefits of fiber-oriented wireless systems are discussed focusing on an application board scheme to facilitate new service deployment in light of intelligent networks. Dynamic range improvement technologies to remove interference are highlighted. Overall system performance is calculated for an economical FP-LD. Furthermore, effective modem use and a potential diversity technique are introduced. This strategy will play a role in realizing flexible fiber-optic subscriber networks.

This paper presents the performance of optically controlled MESFETs as photodetectors. The optical performance characteristics such as optic-to-electric responsivity, and BER for a π/4-QPSK signal are experimentally investigated. Measurements are performed by using MMIC compatible MESFETs. Experimental results are also evaluated in comparison with calculated PIN-PD limit. Optic-to-electric responsivity has high gain at lower received optical powers. It is shown experimentally that MESFET photodetectors improve the permissible optical power by 6 dB compared to the PIN-PD limit. Optically controlled MESFETs will provide a novel receivers for fiber-optic systems.

This paper describes the performance of a predistorter implementation to a superluminescent diode (SLD) in fiber-optic wireless systems under the optical reflection. SLD intensity noise and 3rd-order intermodulation distortion (IM3) are experimentally compared with those of DFB-and FP-LD. It is observed that the IM3 of SLD has ideal 3rd characteristics and output noise remains unchanged against the number of optical connectors. It is also found that the predistorter reduces IM3 by 8 dB. Receiver sensitivity of the system is discussed from the view point of overall design. the BER performance of an SLD with predistorter using a π/4-QPSK signal as a subcarrier is also described theoretically and experimentally.

This paper describes an overview of wireless communications based on fiber-radio technologies from the viewpoint of system applications, particularly in the area of microcell radio systems. Feasible fiber-radio networks design are detailed in order to increase system performance and cost effectiveness. The benefits of the evolving fiber-radio microcell system are discussed with a spectral delivery scheme to meet traffic demands. Foreseeable electronic and optic technologies are reviewed in light of the key parameters to optimize the overall system. This strategy will play a role in broadband and flexible networks.

This paper describes a fiber-optic microcell radio system with a spectral delivery switch to meet traffic demands. Optical link performance is discussed from the view points of link loss and noise figure aimed at system design. The theoretical carrier-to-noise ratio (CNR) performance is shown as a function of the input electrical power of the laser and the received optical power. Improvement of dynamic range defined by both CNR and intermodulation distortion is proposed by using the frequency modulation (FM) technique. The experimental results using the proposed technique indicate that the performance is much better than that of conventional methods. Moreover, economical diversity planning delivery methods over fibers are presented. This strategy will provide more cost effective and flexible networks.