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An analog fiber-optic link for concurrent detection and downconversion of microwave signals is reported. Optical amplification is employed in conjunction with electrical power combining of photodetectors to demonstrate link losses of 19.6 and 22.9 dB at RF carrier frequencies of 9 and 16 GHz, respectively. Analytic expressions validating the experimental observations are also developed. The link may be employed to detect phase sensitive or phase-modulated microwave signals and shows excellent potential for application in sensor systems involving remoting of an antenna element.

A high-speed optical modulator with cascaded resonant-type electrodes is presented. To reduce the drive power and switch voltage Vπ and to maintain high-modulation efficiencies, resonant reduced-length electrode structures were cascaded and integrated on LiNbO3. Electrical power coupling into the resonators was realized by a single-input source distributed with electrical power dividers and delay lines. As a result, an optical modulator with four resonant-type cascaded electrodes was fabricated and characterized. This device, with a total active-electrode length as short as 3.4 (4 × 0.85) mm, achieved a switch efficiency Vπ· L of 68 V · mm at 25 GHz at 1.55-μm wavelength, resulting in a drive power 8.7 dB less than that required for a traveling wave modulator with the same active length. [ABSTRACT FROM PUBLISHER]

High-performance Y-branch digital optical switches realized in Ti:LiNbO3 are presented. Their switching response functions have been optimized in terms of switch voltage and crosstalk ratio. The optimization is based on analyzing different types of waveguide shaping and switching arrangements using coupled mode theory and computer simulations. Excellent switching characteristics are achieved with devices exploiting a specially shaped waveguide branch in a dilated switch arrangement. Demonstrated performances include switching voltage as low as 9 V with crosstalk suppression better than 45 dB and fiber-to-fiber losses as low as 4 dB. Polarization independence with crosstalk suppression better than 40 dB over a 1520- to 1570-nm wavelength range is achieved for any applied switch voltage greater than 18 V. These optimized digital optical switches have further demonstrated the capability to reshape electrical input signals at switching rates of several hundred megahertz [ABSTRACT FROM PUBLISHER]

Short-path-length resonant-type high-speed optical modulators are presented. To reduce the active electrode length and enhance modulation efficiencies, different types of resonant electrode structures were investigated using computer simulation tools. Electrical power coupling into the resonators was optimized with a variety of power-feeding circuits. Their resulting optical and electrical behaviors are compared with measurements on modulators fabricated in Ti:LiNbO3. As a result, resonant-type optical modulators are presented that achieve a low voltage-length product of 25 V mm at 30 GHz in the 1.55-μm wavelength range. Fiber-to-fiber loss of a fully packaged phase modulator with an active optical path length as short as 0.7 mm was 2.3 dB [ABSTRACT FROM PUBLISHER]

Frequency dependent drive voltage is reported in velocity matched, packaged, Mach-Zehnder interferometers, made on Z-cut, Y-propagating LiNbO3, with and without etched ridges. Drive voltages of ~7 V at 40 GHz are demonstrated, with the etched ridge device showing a 1/2-1 V advantage. Microwave modeling allowed the extraction of the effects of dispersion in material properties, occurring near the acoustic resonance, on bandwidth and drive voltage [ABSTRACT FROM PUBLISHER]