Abstract: A system or a method for optical signal amplification includes determining a target operating gain of an optical amplifier; determining a target maximum gain of the optical amplifier; determining an active fiber section length such that the optical signals are amplified with at most the target maximum gain; determining a core cross-sectional area size of the active fiber section based on a maximum allowable pulse shape distortion and a target maximum energy per pulse such that high-energy pulses with the target maximum energy per pulse are distorted by at most the maximum allowable pulse shape distortion; and determining an operating pumping power of the pumping device below the maximum pumping power such that the optical signals are amplified with the target operating gain.

Abstract: A method for quantum key distribution includes determining a ratio between a target maximum gain and a target operating gain of an optical amplifier; determining an active fiber section length such that the optical signals with a target maximum signal power are amplified with at most the target maximum gain; determining an operating pumping power of a pumping device below the maximum pumping power such that the optical signals are amplified with a target operating gain according to the determined ratio between the target maximum gain and the target operating gain; and determining a shared key between a first data processing device and a second data processing device by quantum key distribution comprising amplifying the optical signals via the optical amplifier by operating the pumping device at the operating pumping power.

Abstract: A system and method for authenticating an optical fiber key includes selecting a plurality of at least partially randomized challenge pulse parameters, generating a first optical challenge pulse based on the plurality of at least partially randomized challenge pulse parameters, determining an optical response signal based on a reflected signal of the first optical challenge pulse from the optical fiber key, applying a comparing algorithm the optical response signal and an expected response based on previously recorded optical response signals of the optical fiber key to a reference optical challenge pulse for determining a similarity metric, and authenticating the optical fiber key based on the similarity metric.