Bidirectional EDFA Research Articles

Optically synchronized unidirectional optical amplifier-based coherent optical fiber links.

We report on the realization of a unidirectional transmission-based bidirectional erbium-doped fiber amplifier (UTB-EDFA) for the coherent optical fiber links. By applying an optical phase-locked loop (OPLL) between the two unidirectional EDFA (Ui-EDFA) paths, the annoying uncorrelated phase noise between the two paths can be largely suppressed. Promisingly, we can independently optimize the gains of the UTB-EDFAs for bidirectional transmissions, resulting in higher net gain acquired compared with the conventional single-path bidirectional EDFA (SPBA)-based ones. We demonstrate that the fractional frequency instability of the UTB-EDFA-based scheme can be decreased by 26.3% over the most asymmetrical 100 km two-way optical frequency comparison (TWC) system compared with the SPBA-based ones and, more importantly, can acquire higher net gain for unevenly distributed sub-links over ultra-long fiber links, such as 1000 km, by independently optimizing the gains. This technique paves the way for the applications of large-scale fiber networks.

Detection limit improvement for a gas concentration measurement system using space-domain active fiber cavity ring-down sensing technology

Trace gas sensors have received extensive attention and have become particularly attractive for applications in toxic gas detection, medical diagnostics, pollution monitoring, industrial emission measurement, and so on. However, it is still a critical challenge for gas sensors to simultaneously achieve high sensitivity and low detection limits while performing well in stability. Here, a space-domain active fiber cavity ring-down (FCRD) gas sensing technique was proposed to develop a high-performance gas sensor. Taking advantage of the active FCRD sensing technique and frequency-shifted interferometry, the proposed gas sensor exhibited a high sensitivity of 1.122km−1/%. Importantly, introducing a bidirectional EDFA into the fiber cavity further enhances the light–gas interaction, resulting in a low detection limit of 55 ppm, which is much lower than that of most reported gas sensors. Moreover, a good stability of 0.58% can be achieved due to the combined effect of the proposed technology using differential detection to eliminate DC noise, as well as common-path interference to eliminate common-mode noise and the use of continuous light to stabilize the optical power in the fiber cavity for suppressing the gain fluctuations of EDFA.

Resilience to Passive Attacks of a Secure Key Distribution System Based on an Ultra-Long Fiber Laser Using a Bi-Directional EDFA

In this paper, we study the implementation of a secure key distribution system based on an ultra-long fiber laser with a bi-directional erbium-doped fiber amplifier. The resilience of the system was tested against passive attacks from an eavesdropper. A similarity was observed in the spectra for both secure configurations of the system and no signature that would allow an eavesdropper to obtain the secure state of the system was observed during the state transitions.

Secure key distribution using an ultra-long fiber laser with bi-directional EDFA

In this paper we describe the implementation of a secure key distribution system based on an ultra-long fiber laser with a bi-directional erbium doped fiber amplifier. The resilience of the system was tested against passive attacks from an eavesdropper, having been observed a similarity in spectrum for both secure configurations of the system.

Simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case

Abstract This study has demonstrated the simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case. The output power, max. Q factor and light signal/noise ratio variations are clarified with pump power variations at the bidirectional amplification EDFA amplifier for the previous/proposed models at optimum EDFA length of 8 m. As well as the output power and max. Q factor variations with EDFA amplifier length variations are demonstrated at the bidirectional amplification EDFA amplifier for the previous/proposed models at various pump power levels. The optimum operation efficiency case is observed at 8 m EDFA amplifier length and 120 mW pumping power.

WDM PON purpose remote pumped bidirectional EDFA using cascading FBGS as a pump reflector

ABSTRACTWe proposed a remote pumped bidirectional C+L band fiber amplifier for wavelength division multiplexing passive optical network. A high‐reflectivity pump reflector using three cascading fiber Bragg gratings is designed to reflect the residual pump power for L‐band amplification. Both the gains for C‐band and L‐band are larger than 10.0 dB under −10 dBm launched power. Using the remote pumped bidirectional fiber amplifier, the power penalty is only 0.82 dB after 10 Gb/s, 24 km bidirectional transmission. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2553–2556, 2013

A 240 km Reach DWDM-PON of 8-Gb/s Capacity using an Optical Amplifier

We demonstrate a 240 km reach DWDM-PON at 8-Gb/s capacity based on wavelength-locked Fabry-Perot laser diodes and a bidirectional EDFA. We achieve a packet-error-free transmission in both the 64 upstream and 64 downstream channels, guaranteeing a 125 Mb/s symmetric data rate per user. There is no noticeable dispersion penalty. The power penalty due to the crosstalk induced by the DWDM transmission and detuning between AWGs is less than 1.2 dB, when the detuning is within ${\pm}0.12 nm$ .

An all-optical 2R regenerator using a compact self-seeded Fabry-Pe/spl acute/rot laser diode incorporated in a bidirectional EDFA

An all-optical 2R regenerator, based on a compact self-seeded Fabry-Peacuterot laser diode with a 10-mm-long embedded fiber Bragg grating cavity, and a bidirectional erbium-doped fiber amplifier, is proposed and experimentally demonstrated to execute all-optical 2R regeneration at 10 Gb/s. Compared with the conventional 1R regeneration, the proposed scheme has achieved significant 6.4-dB improvement of power penalty at bit-error ratio =10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> in the transmission experiment over 100-km standard single-mode fiber

Repeated Bidirectional Transmission Using Two 4-Port Optical Circulators and a Bidirectional EDFA without Isolators

By using a newly designed bidirectional erbium-doped fiber amplifier, we demonstrated a 2×2.5 Gb/s repeated bidirectional transmission over a 100-km single-mode fiber. Two tunable optical bandpass filters were used to suppress the Rayleigh backscattering and amplified spontaneous emission in the bidirectional transmission system. The bit error rate performances were measured for both directions. A negligible power penalty of 0.2 dB for the 2×2.5 Gb/s transmission due to backreflections was observed when comparing the bidirectional transmission with single-channel, unidirectional transmission.

A theoretical analysis of amplification characteristics of bi-directional erbium-doped fiber amplifiers with single erbium-doped fiber

Based on the discussion of the structure scheme of bi-directional EDFA (Bi-EDFA) with single erbium-doped fiber (EDF) which can efficiently suppress the internal reflections, a rate equation model for the Bi-EDFA is developed to calculate the signal gain, pump absorption and output noise spectrum. The effects of numbers of signals, pumps of arbitrary direction, amplified spontaneous emission (ASE) and inherent loss are taken into account. Using this model, the influence of EDF length, input signal power, pump style and pump power on the gain characteristics of the Bi-EDFA is analyzed. The forward and the backward noise figures versus bi-directional input signal power for different pump styles are also investigated. With these results, the optimal design for Bi-EDFAs in optical fiber communication systems and networks can be achieved.

Bidirectional Amplification in an EDFA with Balanced Input Signals and Pumps

Based on a modified two-level Er 3+ lasing model and its numerical solution, power evolution, gain saturation, optimal EDF length, and noise characteristic in a bidirectional EDFA (BiEDFA) with balanced input pumps and signals are discussed and compared with that in forward and backward pumped EDFAs. Larger gain and less noise are given by BiEDFA than the other two kinds of EDFAs with the same pumps and signals. In addition, bidirectional semiconductor light amplifiers are considered.