Optoplex's Reconfigurable Optical Add/Drop Multiplexer (ROADM) module, also known as Tunable Optical Add/Drop Multiplexer (TOADM), is based on a proprietary micro-optics and micro-actuator design, athermal packaging technology, and state-of-the-art thin-film coating. When receiving a stream of optical signals of a plurality of wavelengths from the Input-Port (IN), this 3-port ROADM device directs a selected channel to the Drop-Port (ADD/DROP) and the remaining channels to the Express-Port (EXP), as depicted in the figure below. This tunable feature can also be used for adding a channel, when the device is used in reverse. Cascading two ROADM modules, simultaneous add and drop functions can be achieved. Each single ROADM device is optimized to cover either C- or L-band wavelengths. The standard 100- or 200-GHz channel spacing ROADM products allow for single-channel drop. Customized banded-channel drop ROADMs are available upon request.