Abstract: Methods and systems for eliminating extinguish losses in a hub ring network that includes Optical Add Drop Multiplexers (OADMs). The need for a wavelength extinguishing function is eliminated by ensuring that when a wavelength is added to the optical path at a certain node in the ring, the arriving traffic in the path before the addition does not contain that wavelength. The methods include using different wavelengths for the drop and the add operations, ensuring that a trough traffic does not include local ADD wavelengths which are subsequently combined with the through wavelengths, and bi-directional transmission on one or two separate fibers of identical dropped and added wavelengths. Systems include the use of simple, inexpensive, half or fully dynamic OADMs implementing the low-loss functionality.

Abstract: A safety shutter module adapted to fit onto a standard fiber-optics connector which terminates a transmission line conveying light signals of high intensity to be received by an adapter when it is coupled to the connector. When decoupled, these light signals leak from the front end of the connector and are radiated therefrom. This radiation is hazardous to the eyes of individuals exposed thereto. The module is composed of a cap that fits onto the connector and is provided with a visor that projects beyond the front end, the visor having a hinged shutter plate that depends therefrom to block the radiation. But when the adapter is plugged into the connector, it then acts to swing the shutter plate upwardly against the visor to admit the adapter and unblock the connector.