Edmond J. Murphy

16/spl times/16 strictly nonblocking guided-wave optical switching system

We report the first demonstration of a complete 16/spl times/16 strictly nonblocking guided-wave optical switching system. The system, based on a three-stage extended generalized shuffle network, includes 448 directional coupler switch elements in 23 packaged modules. The modules are mounted in a single equipment cabinet and are controlled with a PC-based switching algorithm. We report results of extensive measurements on device and system performance. The devices and system exhibited low uniform voltages. Low loss, low crosstalk, and broad bandwidth. This lithium niobate based system operated continuously and without maintenance for a period of 20 months.

Low crosstalk 4 × 4 TiLiNbO 3 optical switch with permanently attached polarization maintaining fiber array

Several low crosstalk 4 × 4 crossbar optical switch arrays have been fabricated for use at \lambda = 1.3 \mu m. Each array consists of 16 independently functioning directional coupler switches. We describe the typical device performance characteristics. The average insertion loss is 5.2 dB. Crosstalk levels routinely measured < -35 dB. The voltage required to operate the device is ≈ 13 V. The inputs to one of the device arrays were permanently attached to four laser transmitters using lensed polarization maintaining fiber at the laser end and an array of polarization maintaining fibers at the device end.

Fiber attachment for guided wave devices

Reviews the status of fiber attachment to guided wave devices. Current methods for achieving low fiber-waveguide-fiber insertion loss are discussed and techniques for aligning and permanently attaching fibers are described. >

Permanent attachment of single-mode fiber arrays to waveguides

We report on coupling arrays of SM fibers in silicon V - grooves to waveguides. Arrays with up to 12 fibers have been permanently attached to waveguides with an average excess loss of 0.3 dB per interface. We discuss a subtle, heretofore unreported effect of polarization on fiber-waveguide insertion loss and we describe the first measurements of waveguide-mode position as a function of polarization. In general, the modes of a Ti:LiNbO 3 waveguide peak at different positions. This results in different optimum positions for coupling and thus leads to an unavoidable excess loss when attaching fibers. For low-loss waveguides, we predict a minimum excess loss of 0.25 dB per interface.

A six-channel wavelength multiplexer and demultiplexer for single mode systems

We have fabricated and evaluated the first single mode wavelength multiplexer based on a diffraction grating and strip waveguides. The waveguides were employed to minimize the physical spacing between inputs in order to maximize the ratio of channel width to channel separation. The center channel insertion losses for the six channel device were 6.4, 4.9, 6.0, 5.6, 6.8, and 7.8 dB at 1279, 1308, 1338, 1508, 1536, and 1566 nm, respectively. The 1-dB full channel widths averaged 6.0 nm. A matching demultiplexer with multi-mode outputs was also fabricated. The center channel insertion losses were 0.9, 1.1, 1.2, 1.7, 1.8, and 2.1 dB at 1278, 1310, 1337, 1505, 1533, and 1563 nm, respectively. Full 1-dB channel widths ranged from 15 to 11 nm. Out of band rejection exceeded 35 dB.

Low-loss coupling of multiple fiber arrays to single-mode waveguides

A method for obtaining permanent low-loss couping between arrys of single-mode fiber and Ti:LiNbO3waveguides is described. The technique, based on the use of silicon chip V-grooves, simplifies the coupling problem by simultaneously aligning the entire array and by providing a large surface area for a higher integrity adhesive bond. At\lambda = 1.3 \mum, we measure an average 1.9-dB coupling loss (exclusive of propagation loss) for the assembled array. The average excess loss due to the fiber array is 0.8 dB. We present an analysis of the effect of various types of array misalignment on coupling efficiency. Angular alignment and array periodicity are found to be critical. If the fiber and waveguide periodicities are matched exactly, the fibers need only be placed within\pm 1.3\mum of their optimum position to maintain coupling efficiencies greater than 90 percent.

Guided-wave optical time delay network

A hybrid optical time delay unit using lithium niobate switches and precisely produced fiber loops is described. Three prototypes of the device were fabricated and characterized. The measured optical extinction ratio between time slots is typically /spl Lt/25 dB. On average, delay values are within 0.7% of their design values. The device is a 6-b (64 time slot) delay unit with 44 picosecond per increment.

Uniform 8/spl times/8 lithium niobate switch arrays

We report the fabrication and characterization of two packaged 8/spl times/8 Ti:LiNbO/sub 3/ switch arrays. The devices, with their polarization-maintaining fiber arrays, exhibit low crosstalk and excellent uniformity in control voltages and insertion loss. >

Simultaneous single-fibre transmission of video and bidirectional voice/data using LiNbO/sub 3/ guided-wave devices

A system experiment which uses integrated optics to effect bidirectional transmission on a single-mode fiber is described. The system has practical applications and provides more functionality than previously reported experimental systems. The system consists of a video link (180 Mbit/s) and a voice/data link (1.54 Mbit/s) to the end user and a return voice/data link (1.54 Mbit/s) from the end user. Two LiNbO/sub 3/ devices are used to externally modulate lasers and a third is used in a novel way to demultiplex the incoming signals and to eliminate the need for an optical source at the users end. The system operated over 4 km of standard single-mode fiber with a BER >

Fiber-Waveguide Interconnection Technology

This paper discusses various aspects of fiber-waveguide interconnection technology. Theoretical alignment tolerances for various degrees of freedom are considered. Methods for attaching individual fiber and fiber arrays to guided wave devices are described. Recent results on self-aligned fiber array-waveyuide attachment and on self-oriented arrays of polarization maintaining fibers are presented.