Tibor Berceli

Microwave Photonics—A Historical Perspective

Microwave photonics is a rapidly-growing interdisciplinary field linking microwave and optical technologies. This paper intends to trace the evolution of microwave photonics over the last three decades emphasizing some major research areas and application fields. Currently, microwave photonics is a vivid research area with several practical applications. In this paper, we attempt to project potential future trends as well.

Microwave-frequency conversion methods by optical interferometer and photodiode

Frequency conversion in fiber-optic systems like subcarrier multiplexed (SCM) systems is now to be used in many applications for both digital and analog signals. The performance of two different optoelectronic configurations, both used for frequency conversion in the microwave frequency range, are compared here. In the first case, mixing is achieved by a Mach-Zehnder (MZ) interferometer, while in the second case, photodiode mixing is presented. Experimental investigations are presented at the optical wavelength of 1.3 /spl mu/m. In both cases, promising results have been achieved.

A new high-efficiency optical-microwave mixing approach

High sensitivity reception is a crucial problem of fiber radio links. A significant improvement is obtained by applying a new approach called optical-microwave double mixing. The new approach can provide as much as 30 dB of higher mixing product in a narrow-band compared with the direct detection applying only additional passive components. Detailed investigation of the optical-microwave double-mixing method is shown to get optimum adjustment for specific applications. The new method is advantageously used for the reception of subcarrier-multiplexed optical signals.

Optimum configuration of multiloop optoelectronic oscillators

We are concerned with providing a generally applicable optimization method for harnessing the low-phase-noise microwave-millimeter-wave signal generation capabilities of optoelectronic oscillator (OEO) structures. The gained benefits include the possibility of using inexpensive, commercially available bandpass filters; single-mode operation; equidistant spacing of modes; and total cancellation of spurious content in the output signal. Our theoretical ascertainments and simulation data are underlined by numerous experimental results, which were gained through measurements on OEO setups containing one, two, or three parallel connected optical loops. This design method also makes it possible to improve the oscillators performance, obviating the need for a filter of outstanding performance, ultimately of an unreachably high Q value and low thermal sensitivity.

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.

Noise suppression of Nd:YVO/sub 4/ solid-state lasers for telecommunication applications

This paper is intended to elaborate on the investigation and suppression of the relative intensity noise of a diode pumped Nd:YVO/sub 4/ microchip laser. In addition to noise suppression at the relaxation oscillations, noise analysis is also reported. For these investigations a very simple, rate-equation-based model of the laser transfer function was used.

Thermopile antennas for detection of millimeter waves

A thermopile structure is proposed for the detection of microwave/millimeter wave radiation. The thermopairs in the suggested linear arrangement function as antennas. 5.58 V/W responsivity was achieved at 100 GHz with 40 serial connected thermopairs. The experimentally observed polarity and frequency dependence convincingly verify the proper detector operation.

Optical subcarrier label swapping by semiconductor optical amplifiers

The semiconductor optical amplifier (SOA) can be used as an efficient high-speed modulator. The paper presents optical subcarrier multiplexed label swapping/reinsertion utilizing this device associated to the wavelength converter block in packet switched all optical networks. For that purpose the modulation response and nonlinear behavior of SOAs are analyzed and experimentally demonstrated.

A new approach for optical millimeter wave generation utilizing locking techniques

A new approach is presented for the optical generation of millimeter waves. Instead of the millimeter wave signal, one of its subharmonics is optically transmitted and the millimeter wave signal is generated utilizing the subharmonic signal as a reference. This way the optical components become much simpler and cheaper. In this procedure a crucial point is the frequency division at millimeter wave frequencies. For this purpose a new method is introduced: the superharmonic injection locking of oscillators. The main advantage of the new approach is that it is applicable even for frequencies at shorter millimeter waves.

Improvements in the Linearity of Semiconductor Optical Amplifiers as External Modulators

Semiconductor optical amplifiers (SOAs) can be advantageously utilized as external modulators because they can simultaneously perform two functions: amplification and modulation. When the SOA is used in a subcarrier multiplexed system, the modulation linearity is a crucial property. In this paper, theoretical and experimental investigations are presented with the result of improved modulation linearity. By proper adjustment of the operation point and by careful optical matching, a significant improvement in the modulation linearity and also in the spurious-free dynamic range is achieved, along with high modulation sensitivity and wide bandwidth.