Abstract: A system and method for providing eye-safety protection during operation of a lumped optical amplifier. The method is based on monitoring of continuous out-of-band Raman amplified spontaneous scattering (ASS) created by the amplified signal in an optical communication network span coupled to an output port of the lumped optical amplifier. The system includes at least one gain stage for providing an amplified signal introduced into the span, a monitoring unit for performing the continuous Raman ASS monitoring, and a control unit operative to detect and analyze in real-time changes in the ASS power, and upon determination that such changes indicate an open span, to reduce the power of the amplified signal or shut down the gain stage.

Abstract: A method and apparatus for automatic shut-down and start-up of optical amplifiers in wavelength division multiplexed (WDM) optical networks include use of an optical channel monitor (OCM) to monitor loss and return of an input signal. By using the OCM to separately monitor the power level of each individual channel, it is possible to detect loss of all channels or return of a single channel even in the presence of ASE at the amplifier input. The OCM receives a fraction of the input power to the amplifier via an optical tap at the amplifier input, and provides an electrical output to a control unit corresponding to the optical power level of each individual WDM channel. Based on this electrical output, the control sends a shut-down or start-up signal to the pump unit within the amplifier.

Abstract: An apparatus for optical amplification that imparts to a narrow band optical amplifier, specifically an Erbium dope fiber amplifier (EDFA), gain properties found in wide band optical amplifiers. In one preferred embodiment, the apparatus comprises an EDFA and an externally attachable (to the EDFA) module that includes a single un-pumped Erbium doped fiber (EDF) connected to a gain flattening filter (GFF). The GFF may be internal or external to the module. In another embodiment, the apparatus comprises an EDFA and an externally attachable module having a plurality of un-doped EDFs with different lengths, switchably connectable to the GFF and the EDFA to provide the required wide-band gain properties.