Abstract

Large-scale WDM systems contain wavelength-selective filters, switches and multiplexers which must be tolerant of moderate wavelength channel misalignment and can be cascaded without severe accumulated shrinkage of the effective passband width. These requirements demand that wavelength-selective components possess nearly rectangular spectral profiles. In this paper, we describe the flattest acousto-optic wavelength-routing switch yet reported. A multi-cycle SAW directional-coupler-weighted AOTF was fabricated on XY lithium niobate which posessed a 3-dB width of 2.52 nm and a -20-dB width of 0.89 run. For comparison, an ideal apodized AOTF with the same 3-dB width would have a -20 dB width of only 0.33 nm. In this paper we describe WDM switch ; requirements for transmission band flatness, present our filter design and device evaluation and compare our results with the work of previous authors.

© 1996 Optical Society of America