T. Marozsak

Transmission Characteristics of All Semiconductor Fiber Optic Links Carrying Microwave Channels

An experimental and theoretical study is presented for the transmission characteristics of all semiconductor fiber optic links carrying microwave channels. The nonlinear distortion and signal to noise ratio are investigated and evaluated in case of multi-carrier transmission. Extremely high spurious free dynamic range is presented achieved by a direct modulated semiconductor laser.

A new optical distribution approach for millimeter wave radio

In the proposed picocellular radio system a microwave reference and subcarrier multiplexed radio signals are distributed optically. The millimeter-wave carrier is generated by phase locking technique. This approach is not affected by dispersion and utilizes inexpensive devices.

Fiber-dispersion compensation techniques in optical/wireless systems

Carrier frequencies of point-to-multipoint systems are pushed into the higher microwave (MW) or millimeter-wave (mmW) range due to the increasing demand for broadband services and growing number of new subscribers as well as due to lack of sufficiently wide unused radio channels in traditional communication frequency bands. High free space loss of MM wave frequencies reduces the lengths of the wireless links in the radio access part of these systems. Therefore the need for involving fiber-optical techniques in point-to-multipoint systems becomes evident. Optical transmission and distribution of signals up to the last mile offer several advantages. In such combined optical/wireless systems the base stations are connected to the central station through optical fibers. Subscribers are accessed by only few hundred meters long wireless links in the picocells employing MM wave carriers.

A new microwave amplifier nonlinearity measurement method

The measurement of the nonlinearity parameters is usually cumbersome and not accurate enough. In this paper a new method is presented for the measurement of the nonlinearity characteristics, i.e. for the AM compression and AM-to-PM conversion. The new method offers an easy measurement process which is widely applicable. It does not need special instrumentation. The new method has another important advantage: the dynamic behavior of the nonlinearity characteristics can also be obtained in a simple way. Utilizing the new measurement method the nonlinear characteristics of a microwave amplifier have been determined

Vertical cavity surface emitting lasers in radio over fiber applications

Theoretical and experimental study of using direct modulated vertical cavity surface emitting lasers in radio over fiber applications is presented. The nonlinear distortion and signal to noise ratio are investigated and evaluated in the case of short-range multi-carrier transmission. Nonlinear characterization and comparison of different kinds of semiconductor lasers are also presented.

A combined optical-wireless broadband Internet access: transmission challenges

The demand for high bit rate Internet access with portable computers is rapidly growing and needs an easily configurable, fast local area network in a combined system optical transmission can provide high bit rate and radio connection to the personal computers ensures the flexibility and comfort in establishing network connection. In this paper the transmission challenges of both the wireless and optical sections are investigated based partly on the results obtained in the FRANS project of the European Union.

New carrier generation approach for fiber-radio systems to overcome chromatic dispersion problems

A new approach for the generation of millimeter wave (MMW) carriers in fiber-radio systems is presented. A subharmonic of the carrier is transmitted to the radio nodes over the fiber-optic network. At each base station the MMW carriers are generated by a phase locked oscillator (PLO) using harmonic mixing technique. Due to the subharmonic reference transmission, chromatic dispersion in the optical path is avoided. Further advantage is the inherent possibility of channel selection to avoid radio interference between adjacent transmitters.

Circuit model for multiple transverse mode vertical-cavity surface-emitting lasers

The modeling of multimode operation in vertical-cavity surface-emitting laser diodes is difficult because spatial interaction between modes makes the problem very complex. In this paper, a novel circuit model is presented for such lasers, which is based on spatially dependent rate equations, and thus spatial hole burning and carrier diffusion are taken into account. These effects are studied in direct-modulated microwave vertical-cavity surface-emitting lasers by showing linear and nonlinear simulation examples in both time and frequency domains.

A new approach for RIN peak and phase noise suppression in microchip lasers

This paper is concerned with the suppression of the relative intensity noise (RIN) peak and phase noise of a diode pumped Neodymium-doped Lithium Niobate (Nd:LiNbO/sub 3/) microchip laser. Relaxation oscillations result in about 15-20 dB noise peak above the flat noise at 350 kHz offset frequency. In case of high quality requirements this noise peak is significantly disturbing. In this paper a new approach is presented for the suppression of the RIN peak and phase noise in microchip lasers.

A Novel Optical Cellular Millimeter Wave Radio System

A novel optical cellular millimeter wave radio system is presented. The well-known methods in which the millimeter wave signal is distributed via a fiber have many drawbacks because they need very high speed photonic components. These problems are overcome by the new approach which utilizes a low frequency reference signal to phase lock a millimeter wave oscillator. The advantage of the new approach is in the application of low cost photonic components and in the small sensitivity to the fiber dispersion.