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Evolution of first-order sidebands from multiple FWM processes in HiBi optical ...
Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.The generation of two idler waves inside a high birefringent (HiBi) optical fiber through three four-wave mixing (FWM) processes is studied theoretically. The coupled-equations for the field amplitudes are derived and analytically solved, in the co-polarized and orthogonal polarization schemes. The obtained solutions take into account the delayed Raman response of the medium. The polarization sensitivity of the...
Broadband polarization pulling using Raman amplification
Muga, Nelson J.; Ferreira, Mario F. S.; Pinto, Armando N.The Raman gain based polarization pulling process in a copropagating scheme is investigated. We map the degree of polarization, the angle between the signal and pump output Stokes vectors, the mean signal gain and its standard deviation considering the entire Raman gain bandwidth. We show that, in the undepleted regime (signal input power similar to 1 mu W), the degree of polarization is proportional to the pum...
Polarization-entangled photon pairs using spontaneous four-wave mixing in a fib...
Almeida, Álvaro J.; Carneiro, Steven R.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We generate polarization-entangled photon pairs in the 1550-nm wavelength telecom band, using spontaneous fourwave mixing in a highly nonlinear fiber loop. With accidental coincidences subtracted, we obtain coincidence fringes with visibilities greater than 86%, and thus observe a violation of Clauser, Horne, Shimony and Holt (CHSH) inequality by 2.7 standard deviations. The experimental setup is built using on...
Correlated photon-pair generation in a highly nonlinear fiber using spontaneous...
Almeida, Álvaro J.; Martins, Luís M.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We generate 1550 nm correlated photon pairs through the spontaneous four-wave mixing (SpFWM) process in a highly nonlinear fiber (HNLF). The pair source quality generation is evaluated by the coincidence-to-accidental ratio (CAR) parameter. It is verified that the spontaneous Raman scattering (SpRS) photons generated inside the fiber contribute to the degradation of the source. Nevertheless, a CAR value of 2.77...
Time coincidence of entangled photon pairs using spontaneous four-wave mixing i...
Almeida, Álvaro J.; Carneiro, Steven R.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We obtained a source of entangled photon pairs in the 1550-nm wavelength band using spontaneous four-wave mixing (SpFWM) in a Sagnac fiber loop. Time coincidence of entangled photon pairs was verified for a 300-m dispersion-shifted fiber (DSF), using an avalanche photodiode (APD). ; QuantTel - Quantum Secure Telecommunications ; Quant- PrivTel - Quantum Private Telecommunications - PTDC/EEATEL/ 103402/2008
Fiber-optical communication system using polarization-encoding photons
Almeida, Álvaro J.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We present a single-photon source based on the stimulated four-wave mixing process with adjustable linear state of polarization. This source allowed us to generate non-orthogonal states of polarization, that can be used for quantum key distribution experiments. The average number of photon counts as a function of the angle of the analyzer was obtained for two non-orthogonal linear states of polarization. The re...
Single-photon source based on FWM with adjustable linear SOP
Almeida, Álvaro J.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We present a setup able to generate and detect single photons in optical fibers using the stimulated four-wave mixing (FWM) process. The results show an accurate generation of single photons at four different linear states of polarization (SOPs), with angles 0, 45, 90 and -45 degrees. The detection was performed in back-to-back configuration and after transmission over an optical fiber with a length up to 10 m.
Single-photon source with adjustable linear SOP
Almeida, Álvaro J.; Fernandes, Gil G.; Pinto, Armando N.In this work we generate and detect single photons in optical fibers using the stimulated four-wave mixing (FWM)process. The results show an accurate generation of single photons at four different linear states of polarization (SOPs), with angles 0, 45, 90 and -45 degrees. ; QuantTel - Quantum Secure Telecommunications
Effect of soliton interaction on timing jitter in communication systems
Pinto, Armando N.; Agrawal, G. P.; Rocha, José FerreiraTiming jitter in soliton communication systems is studied, taking into account both soliton interaction and amplifier noise, Deviations from Gordon-Haus jitter for closely spaced solitons are observed. A new analytical model for the timing jitter is proposed, The model presented considers interaction in a random sequence of solitons and the effect of the amplified spontaneous emission noise added in each amplif...
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