G.H. Smith

Overcoming chromatic-dispersion effects in fiber-wireless systems incorporating external modulators

We demonstrate two techniques to reduce the effects of fiber chromatic dispersion in fiber-wireless systems incorporating external modulators. We theoretically and experimentally show that the achievable link distance can be increased by varying the chirp parameter of the modulator to give large negative chirp using a dual-electrode Mach-Zehnder modulator (MZM) biased at quadrature. In addition, we show that dispersion can be almost totally overcome by implementing a simple method using the dual-electrode MZM to generate an optical carrier with single sideband (SSB) modulation. We demonstrate the transmission of a 51.8-Mb/s pseudorandom bit sequence (PRBS) at 12 GHz over 80 km of standard single-mode fiber using the SSB generator and measure a bit-error-rate (BER) power penalty due to fiber dispersion of less than 0.5 dB for a BER equal to 10/sup -9/.

A millimeter-wave full-duplex fiber-radio star-tree architecture incorporating WDM and SCM

We propose a full-duplex millimeter-wave fiber-radio network for providing wireless customer access to broadband services. It consists of a hybrid star-tree architecture connecting remote antenna base stations to a central control office (CO) by incorporating wavelength-division multiplexing (WDM) of the optical signals and subcarrier multiplexing (SCM) of the radio signals. These multiplexing schemes allow the sharing of equipment at the CO and therefore enable a simple radio distribution architecture to be implemented. We also demonstrate a 35.5-39.5-GHz full-duplex fiber-radio star-tree network, featuring three WDM carriers in the downstream and a single carrier in the upstream. Each downstream wavelength carries three 155-Mb/s BPSK SCM channels between 35.8-39.3 GHz, while a 37-GHz carrier transports 51.8 Mb/s upstream.

Broad-band millimeter-wave (38 GHz) fiber-wireless transmission system using electrical and optical SSB modulation to overcome dispersion effects

A spectrally efficient millimeter-wave (mm-wave) fiber-wireless transmission system is presented demonstrating downstream transportation of 155-Mb/s BPSK data at 38 GHz over 50 km of standard single-mode fiber and a 5-m wireless link. The effect of fiber chromatic dispersion on the transmission of the mm-wave optical carrier was overcome by using a single dual-electrode Mach-Zehnder modulator to generate optical single-sideband (SSB) modulation with carrier. We also demonstrate a simple technique for obtaining electrical SSB that will allow the effect of fiber dispersion across the bandwidth of the information to be overcome with simple electrical delay equalization. We predict that this fiber-wireless system could permit the transportation of mm-wave signals with large bit rates over long optical fiber distances.

Novel technique for generation of optical SSB with carrier using a single MZM to overcome fiber chromatic dispersion

We demonstrate a novel and simple technique for the generation of optical SSB with carrier using a single Mach-Zehnder modulator to overcome dispersion effects in fibre-wireless systems. A dispersion penalty <0.5 dB for BER of 10/sup -9/ was measured for 51.8 Mb/s BPSK data transmission at 12 GHz over 80 km of fibre.

Dispersion-induced power penalties in millimeter-wave signal transmission using multisection DBR semiconductor laser

In this paper, we present a simple analytical model to characterize the effect of fiber chromatic dispersion when using a multisection distributed-Bragg reflector (DBR) semiconductor laser as a millimeter-wave optical transmitter in a millimeter-wave fiber-radio system. We characterize the dispersion penalty of the laser as a function of the laser operating conditions and establish that the penalty is dependent on the distribution of optical power among the modes in the laser output. This, in turn, is dependent on the spectrum-filtering property of the laser DBR section and the gain profile of the laser. In addition to the dispersion penalty, the stability of the generated millimeter-wave carrier from the multisection laser is investigated, including the detected RF power and resulting phase noise. We establish that a compromise must be made when finding the optimum bias condition of the laser which provides minimum dispersion penalty, maximum received RF power, and minimum phase noise of the generated millimeter-wave carrier.

Millimeter-wave fiber-wireless access systems incorporating wavelength division multiplexing

We present an overview of our recent implementations of mm-wave fiber-wireless systems incorporating wavelength division multiplexing. Critical design issues such as the design of the base-station architecture and the effect of optical crosstalk on the transmission of rf signals are discussed.

Implementation of an upstream path in a millimeter-wave fiber-wireless system

Summary form only given. We demonstrate a simple method for upstream data transmission in a mm-wave fiber-wireless system that incorporates a multisection semiconductor laser as the mm-wave optical transmitter at the remote base station. 51.8 Mbit/s of data at 36.8 GHz is first transported over a 5-m wireless link from the customer unit to the antenna base station, followed by transmission over 40 km of optical fiber back to the central office. We also show theoretically and experimentally that fiber transmission of modulated mm-wave signals via direct modulation of the multisection laser is not significantly affected by fiber chromatic dispersion.

A millimeter-wave full-duplex WDM/SCM fiber-radio access network

Summary form only given. We demonstrate a 35.5-39.5 GHz full-duplex fiber-radio access network, featuring three WDM carriers in the downstream and a single carrier in the upstream. Each downstream wavelength carries three 155-Mbit/s BPSK SCM channels, while upstream there is a 20-Mbit/s BPSK RF channel. The mm-wave signals in the down- and upstream fiber links are unaffected by chromatic dispersion. The network demonstration incorporates 40 km of standard single-mode optical fiber and three 5-m radio cells.

Sensitivity analysis of optical SSB generation using a dual-electrode Mach-Zehnder modulator

Data transmission in a mm-wave optical link incorporating optical SSB modulation via a dual-electrode modulator, has been modeled. Simulations of received eye-diagrams show that the SSB generator is tolerant to errors in phase and power level of the drive signals: /spl plusmn/5/spl deg/ and 3 dB respectively.

A broadband integrated photonic-antenna interface for multiservice millimeter-wave fiber-wireless applications

A broadband integrated photonic-antenna interface is presented that is suitable for application in multiple millimeter-wave fiber-wireless service applications. The antenna base-station module is based on hybrid integrated circuit technology and operates over the entire Ka-band (26 - 40 GHz).