We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultralong fiber laser.This new concept is supported by experimental results sho...We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultralong fiber laser.This new concept is supported by experimental results showing how the radiofrequency spectrum of the laser can be exploited as a carrier to exchange information.The test bench for our proof of principle is a 50-km-long fiber laser linking two users,Alice and Bob,where each user can randomly add an extra 1-km-long segment of fiber.The choice of laser length is driven by two independent random binary values,which makes such length become itself a random variable.The security of key exchange is ensured whenever the two independent random choices lead to the same laser length and,hence,to the same free spectral range.展开更多
Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when be...Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when beam intensities exceed a certain critical value.Optical breakdown associated with irreversible modifications of the refractive index,triggered by multiphoton absorption,has been largely exploited for fiber material microstructuration.Here we show that,for light beam intensities slightly below the breakdown threshold,nonlinear absorption strongly affects the dynamics of a propagating beam as well.We experimentally analyze this subthreshold regime and highlight the key role played by spatial self-imaging in graded-index fibers for enhancing nonlinear optical losses.We characterize the nonlinear power transmission properties of multimode fibers for femtosecond pulses propagating in the near-infrared spectral range.We show that an effective N-photon absorption analytical model is able to describe the experimental data well.展开更多
基金This work was supported by the French National Research Agency(grants LABEX SIGMALIM and ANR 08-JCJC-0122 PARADHOQS)the European Research Council(project ULTRALASER)+2 种基金the Leverhulme Trust(grant RPG-278)the Spanish MICINN project TEC2011-27314(RAMAS)We also acknowledge support by the XLIM Institute(grant VIP2013).
文摘We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultralong fiber laser.This new concept is supported by experimental results showing how the radiofrequency spectrum of the laser can be exploited as a carrier to exchange information.The test bench for our proof of principle is a 50-km-long fiber laser linking two users,Alice and Bob,where each user can randomly add an extra 1-km-long segment of fiber.The choice of laser length is driven by two independent random binary values,which makes such length become itself a random variable.The security of key exchange is ensured whenever the two independent random choices lead to the same laser length and,hence,to the same free spectral range.
基金Ministero dell’Istruzione,dell’Universitàe della Ricerca(R18SPB8227)European Research Council(740355,874596)+1 种基金Region Nouvelle Aquitaine(F2MH,SIP2)National Research Agency under the Investments for the future program(ANR-10-LABX-0074-01 Sigma-LIM)。
文摘Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when beam intensities exceed a certain critical value.Optical breakdown associated with irreversible modifications of the refractive index,triggered by multiphoton absorption,has been largely exploited for fiber material microstructuration.Here we show that,for light beam intensities slightly below the breakdown threshold,nonlinear absorption strongly affects the dynamics of a propagating beam as well.We experimentally analyze this subthreshold regime and highlight the key role played by spatial self-imaging in graded-index fibers for enhancing nonlinear optical losses.We characterize the nonlinear power transmission properties of multimode fibers for femtosecond pulses propagating in the near-infrared spectral range.We show that an effective N-photon absorption analytical model is able to describe the experimental data well.
