B. Lagerstrom

A beam propagation method analysis of active and passive waveguide crossings

A beam propagation method is employed to analyze the characteristics of crossed optical waveguides and related switches, based on such crossed waveguides. The complex coupling properties of passive crossings are highlighted and general design guidelines for passive devices as well as for switches are given.

Optical cross-connect system in broad-band networks: system concept and demonstrators description

A network robust to future evolution in network topologies or transmission formats and bit rates, which would be achieved by introducing an all-optical transparent layer in the transport network hierarchy is considered. The transparency would permit use of physically common fiber lines and nodes for different transmission hierarchies and/or formats. A transparent network could be achieved by combining photonic switching with electronic switching technology in the network nodes. A combination of wavelength routing and space-division switching in the optical layer would increase the capacity, as well as the flexibility in a network, allowing routing with higher granularity within the optical layer. Two optical cross-connect demonstrators have been set up. One demonstrates protection switching and restoration of traffic in a future transport network, and the other demonstrates routing of subscriber signals to different service switches in a local exchange. Space switches, tunable lasers and filters are the key technologies used to obtain enhanced flexibility. >

Pigtailed tree-structured 8/spl times/8 LiNbO/sub 3/ switch matrix with 112 digital optical switches

We report on integrated optics Ti:LiNbO/sub 3/-based 8/spl times/8 switch matrices. The matrix design uses a tree structure with 112 digital optical switches as switch elements. The matrix, which has been pigtailed and packaged in an open package for convenient system demonstrator use, exhibits a worst case insertion loss of less than 15 dB.<<ETX>>

Multilevel polarization modulation using a specifically designed LiNbO/sub 3/ device

Binary and multilevel optical polarization modulation (POLSK) is an innovative transmission technique, suitable for both coherent and direct detection. To prove its feasibility, we have built a flexible polarization modulator based on a specifically designed LiNbO/sub 3/ device. We show that it can generate any state of polarization and therefore it is suitable for transmission of any binary or multilevel POLSK constellation. Once electrically equalized, the modulator has a 4 GHz bandwidth. To test the modulator with actual digital modulation, we set up a coherent binary experiment at 800 Mbit/s, and attained a sensitivity 1.5 dB away from the noise limit of the receiver.<<ETX>>

Monolithically Integrated 4x4 InGaAsP/InP Laser Amplifier Gate Switch Arrays

Monolithically integrated 4×4 semiconductor laser amplifier gate switch arrays comprising twenty-four integrated laser amplifiers have been fabricated and evaluated. We report observation of net positive optical gain between fibres, high extinction ratio, and low crosstalk.

High Speed LiNbO3 Integrated Optics Modulators And Switches

Design considerations for high speed integrated optics components are rewiewed, with emphasis on bandwidth-drive power performance, prospects for integration and polarization control. Experimental results concerning multigigabit modulation of LiNb03 directional coupler switches will be presented, along with work on fiber and microwave coupling and on the associated microwave circuitry.

A LiNbO3 modulator for binary and multilevel polarization modulation

The modulation of the state of polarization (SOP) of light has been recently proposed for transmission of information on optical fibers.1-4 Polarization-shift keying (POLSK) is suitable for both coherent and direct-detection (DD) systems. In either case, both binary and multilevel schemes are possible.

Stabilization of a Ti:LiNbO(3) directional coupler.

A simple electronic feedback is used to bias a directional coupler in the cross or bar state to improve the overall performance of the package.

Binary and multilevel polarization modulation: experimental system design

This paper is a preliminary report on an ongoing experimental effort aimed at the implementation of a prototype of a lightwave digital coherent transmission system based on polarization modulation, or polarization shift keying (POLSK). Several devices specifically designed and built for the experiment are presented. The state of the experimental project is assessed.