501 series multiplexers.

When the upgrade plan for multimode FT3C was changed from three wavelength multiplexing at 825nm, 875nm, and 1300nm to two wavelength multiplexing at 825nm and 1300nm, a simplification of the WDM components became possible. The new components are coded the 501 series multiplexers. The only difference between members of the series is in the length of the common fiber cable. Because the Si-APD used to detect the 825nm wavelength light is insensitive to light at 1300nm, no special demultiplexer is needed at the receiver end of a fiber span. An LDI has been issued and the multiplexers are now in production at AT&T Technology Systems, Reading Works. Testing showed that 501 series multiplexers meet component and system requirements.