Compact switch array provides fast packet routing

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Hassaun Jones-Bey

Researchers at the University of Bristol (Bristol, England) have used a compact indium gallium arsenide phosphide/ indium phosphide (InGaAsP/ InP) vertical coupler optical switch array for high-speed routing of optical data packets.1 The surface dimensions of the 4 × 4 switch array were 1 × 1 mm, and the switching time was less than 1.5 ns. The array was fabricated on an InP substrate, and it used carrier-induced refractive index and gain changes as the switching mechanism. Crosstalk was less than -50 dB, and optical bandwidth was measured in excess of 40 nm.

The researchers mounted the device on an RF submount without temperature control or cooling and modulated the output of a 1554-nm DFB laser with a 10-Gbit/s data stream to provide an input signal. The input signal was passed through a polarization controller and then coupled into the space switch using a lensed fiber (see figure). A pulse generator was synchronized to every other signal packet to send 5-V (80-mA injection current) pulses into the switch array with 10-ns leading and trailing edges. The optical signal was coupled out of the switch using another lensed fiber. The output signal was passed through an optical bandpass filter, detected by a lightwave converter and displayed on an oscilloscope.

Routing of the 10-Gbit/s optical data packets was achieved successfully with a 2-ns interpacket guard-based time, and the researchers expect significant potential for the device in high-speed, all-optical networks because it is bit-rate transparent. For more information, con- tact Richard Penty at


1. S. Yu et al., Electron. Lett. 36(6), 556 (2000).Wdm93963 7

Researchers at the University of Bristol Center for Communications Research have experimentally achieved optical packet routing at switching times less than 1.5 ns and crosstalk of less than -50 dB using a compact space switch array.

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