William A. Dyes

Echelon grating multiplexers for hierarchically multiplexed fiber-optic communication networks

Echelon gratings have many beneficial properties when used as the dispersing mechanism of a fiber-optic wavelength multiplexer including high optical dispersion, high optical efficiency, greatly reduced sensitivity to polarization, simultaneous utility on many wavelength bands, and a capability for hierarchical multiplexing. The use of echelon multiplexers in a hierarchical environment is discussed, and a prototype echelon multiplexer is constructed and used to demonstrate the unique capabilities of this device for creating wavelength division multiplexing systems.

Simplified Z-propagating DC bias stable TE-TM mode convertor fabricated in Y-cut lithium niobate

A TE-TM mode converter, useful at either 0.632 or 0.840 mu m, has been fabricated on y-cut LiNbO/sub 3/ by Ti indiffusion with the channel waveguide placed parallel to the z-axis. For TE polarized input, the maximum TM modulation depth is 97 percent at 0.632 mu m with a 5-V (pp) drive and 99 percent at 0.840 mu m with a 12-V (pp) drive. A similar device operating at 1.3 mu m displays 98-percent TE-TM switching at 68 V. Operation involves only coplanar electrodes placed alongside the channel acting on the r/sub 61/ electrooptic coefficient. A separately deposited buffer layer is unnecessary. Testing indicates a substantially greater tolerance to electrode misalignment than afforded by similar structures formed in x-cut substrates. Data illustrating immunity to photorefractive drift in the presence of a DC bias voltage is presented for 0.840- mu m wavelength operation. >

Self-heterodyne multiterminal system concepts for frequency division multiplexed fiber-optic communication

System structures are described that use a centralized optical source for supplying all optical power needs-signal generation and coherent detection. In the configurations described the following benefits occur. Functional systems can be implemented with already demonstrated, and in many cases readily available components. There is no need for local oscillator optical sources and there is no need to stabilize the local oscillators with respect to a remote transmitter frequency to achieve coherent detection. Increases selectivity against other signal frequencies and increased signal-to-noise result from the use of coherent detection. When configured to equalize reference and signal time delay paths, both slow and fast laser source phase and frequency jitter are compensated for. One may therefore efficiently implemented multiple-access frequency division multiplexed networks in which the individual communication bandwidths are small compared to the linewidth of the laser power source. >

Novel bulk optic multichannel resonator device for close packed wavelength multiplexing.

A simple bulk optic structure is described that is suitable for multiplexing or demultiplexing many closely spaced wavelengths of light. Aside from input/output coupling hardware, the structure is comprised of a single glass, high finesse, Fabry-Perot etalon with a low efficiency diffraction grating etched into one face. The device concept provides a capability for multiplexing ratios in excess of 10, channel frequency separations smaller than 1 GHz, and can be designed to support optical networks having a total communication capacity in excess of 100 GHz. A laboratory model of the multiplexer was constructed and evaluated to demonstrate concept feasibility. The demonstration model, adjusted to demultiplex nine channels separated by 2.2 GHz for a total capacity of 20 GHz, exhibited a throughput optical coupling of -7 dB and a signal-to-crosstalk ratio greater than 15 dB.