Roger Krähenbühl

Fully packaged, broad-band LiNbO 3 modulator with low drive voltage

A low drive voltage of /spl sim/5 V at 40 GHz has been achieved in a fully packaged, broad-band LiNbO/sub 3/ modulator. The excellent response is attributed to nearly perfect velocity and impedance matching, along with very long electrodes (41 mm), low electrode losses, and minimal packaging effects. Very accurate frequency-dependent drive voltages are obtained by the use of independent sets of measurements.

960 Gb/s Optical Backplane Ecosystem Using Embedded Polymer Waveguides and Demonstration in a 12G SAS Storage Array

An optical backplane ecosystem is described and demonstrated that is capable of multi-Tb/s bandwidth and is based on embedded polymer waveguides, passive optical backplane connectors, and midboard optical transceivers with bandwidth up to 28 Gb/s per lane. These systems provide the highest bandwidth-density, lowest power consumption, while maintaining the signal integrity. Ecosystems built around this architecture will provide the bandwidth-density required for next generation fabric interconnect for storage, switching, and routing applications in future high capacity generations of Data Centers and HPC systems. To demonstrate the applicability of this technology, it was used to provide embedded optical connectivity within a functional data storage enclosure.

Performance and modeling of advanced Ti:LiNbO/sub 3/ digital optical switches

High-performance Y-branch digital optical switches realized in Ti:LiNbO/sub 3/ 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.

Investigations on short-path-length high-speed optical modulators in LiNbO/sub 3/ with resonant-type electrodes

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:LiNbO/sub 3/. 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-/spl mu/m 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.

High-Precision, Self-Aligned, Optical Fiber Connectivity Solution for Single-Mode Waveguides Embedded in Optical PCBs

A fully passive, optical fiber connectivity solution for polymer waveguides embedded in electro-optical printed circuit boards (EOCB) is described and its preliminary results for single-mode applications demonstrated. The connectivity solution is based on a pluggable glass-fiber connector interface and a self-alignment packaging technology using high-precision silicon V-grooves. The V-grooves provide precise positioning of the glass-fiber relative to the polymer waveguide through alignment structures on the EOCB, patterned in the same laser direct writing fabrication step as the waveguide core. We realized an EOCB module with an LC-connector pluggable adaptor interface assembled on one side of the EOCB. With this module, we were able to prove for the first time the usability of our connectivity solution for single-mode applications. Coupling losses as low as 1.2 dB between a standard LC-connector and the single-mode polymer waveguide embedded into the EOCB have been reached. This passive packaging solution provides a cost-effective optical connectivity to wave-guides in EOCBs, which will be required in future generations of optical interconnects.

High-speed optical modulator in LiNbO/sub 3/ with cascaded resonant-type electrodes

A high-speed optical modulator with cascaded resonant-type electrodes is presented. To reduce the drive power and switch voltage V/sub /spl pi// and to maintain high-modulation efficiencies, resonant reduced-length electrode structures were cascaded and integrated on LiNbO/sub 3/. 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 /spl times/ 0.85) mm, achieved a switch efficiency V/sub /spl pi///spl middot/ L of 68 V /spl middot/ mm at 25 GHz at 1.55-/spl mu/m wavelength, resulting in a drive power 8.7 dB less than that required for a traveling wave modulator with the same active length.

Reflective digital optical switch (RDOS) for DWDM optical network applications

A novel, high-performance, reflective digital optical switch for use in dense wavelength-division-multiplexed (WDM) network applications is presented. Highly reliable Ti-LiNbO/sub 3/ devices show high-speed polarization-independent reflection modulation with 30-dB ON-OFF ratios over a wavelength range from 1520 to 1570 nm.

Versatile Multifiber Optical Connectivity Solution: From Concept to Realization

Multifiber interconnection technology is one of the important keys to increase package density in optical networks. We present a novel releasable multifiber optical connectivity solution from the initial concept to the functional prototypes. This connectivity solution relies on a V-groove alignment platform and a microlens array. It can, e.g., provide reliable connections between a fiber array and an active optoelectronic component array or between a fiber array and an optical waveguide device. Moreover, within a free-space propagation region, it provides access to collimated optical beams, thus enabling various light manipulation options. The microlens V-groove fabrication process makes use of a dedicated assembly station that has been designed for automation. The microlens array is positioned on the platform, aligned relative to the V-grooves, and fixed with a low-cost adhesive bonding technology. Uniform and stable low losses for fiber-to-fiber coupling via two lenses have been achieved for single-mode and multimode fibers at wavelengths of 850, 1300, and 1550 nm. This connectivity solution represents, therefore, a versatile cost-effective technology for releasable connections of fiber arrays to any other optical multiport device

Compact 90

A compact releasable 90deg optical connectivity solution is proposed, realized, and characterized. It can be used for angled interconnection between two small form factor multifiber connectors, or between one connector and surface mounted multichannel active optical elements such as vertical-cavity surface-emitting lasers and photodetector arrays. This 90deg connectivity system is based on V-groove substrates and an integrated optical microsystem combining two lens arrays and a 45deg mirror. Realized modules feature average fiber-to-fiber optical losses of 1.4 dB (best below 1 dB) for multimode operation over the whole wavelength range from 850 up to 1550 nm. This interconnect solution provides advantages when limited space is available (e.g., in optical distribution frames, splice closures, high-performance computers)