Edgar Weidel

Performance of Lyot depolarizers with birefringent single-mode fibers

Fiber-optic Lyot depolarizers which are attractive for fiber-optic gyros have been studied theoretically and experimentally. It is shown that the amount of residual polarization at the depolarizer output is proportional to the square root of the polarization-maintaining parameter h , yielding a residual polarization of about 1 percent for a fiber-optic depolarizer with h = 1.1 \cdot 10^{-4} /m and a superluminescent diode.

Single-mode fused biconical couplers for wavelength division multiplexing with channel spacing between 100 nd 300 nm

The authors report on single-mode fused biconical couplers tailored to the requirements of wavelength-division-multiplexing systems. The wavelengths of the two channels can be chosen arbitrarily for wavelength separations between 100 and 30 nm. For separations between 150 and 300 nm, the couplers can be manufactured with an accuracy of +or-5 nm at the two operating wavelengths. For decreasing wavelength separation of the channels, the influence of the state of polarization results in an increased inaccuracy of the two wavelengths, increased far-end crosstalk, and power fluctuations after the coupler. This sets a lower limit for channel separation. Good agreement between theory and experiment is achieved. >

Single-mode fused biconical coupler optimized for polarization beamsplitting

A single-mode fused biconical coupler for polarization beamsplitting is described. In the coupling region, standard communication fibers are used. The output fibers are polarization-maintaining. To stop the coupler drawing process accurately, the degree of polarization is measured during the drawing and is used as a criterion. Losses of 0.2 dB are typical, and a minimum extinction ratio of -27 dB is achieved. A usable spectral window as broad as 17 nm with an extinction ratio smaller than -15 dB for both output fibers is obtained. Any specified wavelength for the minimum of the extinction ratio is reached within +or-3 nm. >

Wide passband grating multiplexer for multimode fibers

A grating multiplexer in Littrow-configuration is presented, whose passband width-normalized to channel spacing-is comparable with grating demultiplexers. As shown by calculation, a wide passband is attainable by very small input fiber spacing. Using a standard-(50/125 \mum)-GI-fiber as transmission fiber, a 1-dB pass-band of 30 nm with a channel spacing of 46 nm is achieved in an 8- channel device. The insertion losses for each channel are in the range 1.4-2.5 dB for 8- or 10-channel devices.

Multimode stripe waveguides for optical interconnections

Multimode stripe waveguides for optical interconnections in signal processors were fabricated in BGG31-glass and in 6F44-polyimide. The fabrication technologies were field assisted ion exchange for waveguides in glass and spin coating followed by dry etching for polymeric waveguides. The waveguide dimensions were between 20 and 30 micrometers for the height and between 30 and 40 micrometers for the width. The attenuation was found to be 0.1 dB/cm in glass and 0.8 dB/cm in polyimide. Bends and intersections have been characterized.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.