Erbium-doped Fiber Preamplifier Research Articles

Evaluation of the effect of channel add/drop impact on power transients on the performance of a 10‐GB/S DWDM transmission system with hybrid EDFA/Raman amplification

AbstractWe experimentally assess the impact of the transient effect in the bit error rate of a 30 km 10 × 10 Gb/s DWDM transmission system with hybrid amplification.For that purpose, the analyzed hybrid system is composed by a counter‐pumped Raman fiber amplifier followed by an Erbium doped fiber preamplifier. The results show that the channels adding and drooping have a significant impact on the signal quality, in the worst case scenario a 8‐dB power penalty was obtained. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1225–1228, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25155

Optical Signal-to-Noise Ratio Estimation Using Reference Asynchronous Histograms

This paper presents and experimentally demonstrates a novel method for the estimation of optical signal-to-noise ratio (OSNR) based on the comparison of an asynchronous histogram of the signal under analysis with a reference asynchronous histogram. The latter is acquired from the signal under analysis at a calibration stage. The proposed method allows the use of optical amplification to increase the sensitivity of the optical monitoring system (OMS) by a factor 20 dB, when using an erbium doped fiber preamplifier. In addition, the use of a semiconductor optical preamplifier, initially designed for nonlinear operation at 2.5 Gb/s is used in the OMS to preamplify 40-Gb/s signals, achieving a sensitivity gain of 10 dB. It will be experimentally demonstrated that the proposed method is applicable to 40-Gb/s nonreturn to zero (NRZ) signals arbitrarily degraded by group velocity dispersion (GVD). Furthermore, accurate monitoring of the OSNR of return-to-zero (RZ) signals will also be possible using a simple RZ-to-NRZ converter based on narrow-band optical filtering within the OMS. The proposed method also allows estimating of the GVD-induced OSNR penalty between the signal under analysis and the signal at the calibration stage.

Effective Penalty Reduction in an L-Band WDM System using Hybrid Amplifier with a Dispersioncompensating Module

We demonstrate the combined use of a single laser diode and a fiber ring laser for pumping a Raman-amplified dispersion compensating fiber (DCF) to upgrade an L-Band WDM transmission system at 10 Gbit/s. The broadband DCF module is placed at the output of an L-Band Erbium-doped fiber pre-amplifier, to reduce the power penalties associated to chromatic dispersion. The hybrid DCF-Raman amplifier, provided by two pump-wavelengths originated from a single pump source, permits the L-band channel allocation with efficient transmission performance through a metro-scaled (100 km) standard single mode fiber (SSMF). The performance of eight WDM channels in the L-Band is presented with nearly penalty free operation at 10 Gbit/s, which are corroborated by numerical simulation analysis. The residual power penalties obtained were either close to 1 dB or less for all channels in the L-band. The L-band hybrid pre-amplifier, composed by a single-stage EDFA and a Raman-pumped DCF module, is proposed as an alternative solution for the capacity upgrade of metropolitan WDM transmission systems.

Higher-Order Soliton Compression of Optical Pulses from 5 ps to 20 fs by a 15.1-m-long Single-Stage Step-like Dispersion Profiled Fiber

It has been successfully demonstrated to compress 5 ps optical pulses down to 20 fs by a 15.1-m-long single-stage step-like dispersion profiled fiber (SDPF) through a series of the higher-order soliton compression processes in conjunction with a single and ordinary erbium-doped fiber preamplifier. The SDPF compressor contains two kinds of dispersion-flattened fibers (DFFs) at its end and was composed by fiber-splicing with an aid of an extremely careful cutback method. In addition, we have compared the measured compression profiles in the 20–100 fs range with simulation results calculated on the bases of a few elementary soliton models and some experimentally extracted parameters, which is aimed to investigate and clarify its compression mechanism. It was found out that the standard nonlinear Schroedinger equation works appropriately to some extent even in the 30–100 fs range for the DFF used here, although some difficulty exists in modeling the pulse width evolution in the sub-30 fs range as far as the parameters that we used are concerned.

REAP: recycled erbium amplifier pump

We report a novel erbium doped fiber preamplifier design with a combination of high gain (>40 dB) and low noise figure (3 dB) at 1556 nm for 80 mW of 980 nm pump power. The co-directional single pumped amplifier employs a composite two stage arrangement in which the second stage is pumped with recycled pump not used in the first stage. In addition, we contrast the amplifier performance trade-offs with the insertions of an isolator or a band pass filter or both in between the two amplifier sections. Finally, we demonstrate a receiver sensitivity of /spl minus/37 dBm (156 photons/bit) with a 10 Gb/s optical preamplifier regenerator. >

Power penalty due to optical reflections in erbium-doped fiber preamplifier

The effect of optical reflections in erbium-doped fiber amplifiers (EDFAs) is investigated primarily as they are used for preamplifying the received signal in a digital transmission system. Both an increase in amplified spontaneous emission (ASE) due to its multiple reflection and an increase in relative noise intensity (RIN) due to interferometric phase-to-intensity-noise conversion are considered as sources of degradation of the receiver sensitivity. The power penalty is calculated and confirmed experimentally.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

BOA: balanced optical amplifier

An efficient balanced optical amplifier (BOA) configuration is presented. In this technique, the four ports of a multiplexer coupler are used to combine signal and pump in a symmetric fashion. The use of this single-coupler-based design in both 980-nm pumped erbium-doped fiber preamplifier and power booster arrangements, is described. It is shown that the BOA design provides pump redundancy, dual pumping while preventing pump cross-talk, automatic gain control (AGC) potential, and self-gain equalization capability over the whole 1550-nm transmission window.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-sensitivity two-stage erbium-doped fiber preamplifier at 10 Gb/s

An optical preamplifier with a record sensitivity of -38.8 dBm (102 photons/bit) at 10 Gb/s has been demonstrated. When the amplifier is employed in a practical link without an input isolator, the sensitivity is only slightly degraded to -37.6 dBm (135 photons/bit) by input coupling losses and feedback due to Rayleigh backscattering in the transmission fiber. It is predicted that this penalty can be reduced to 0.15 dB with an improved isolator in the composite EDFA.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

2.488 Gb/s-318 km repeaterless transmission using erbium-doped fiber amplifiers in a direct-detection system

The authors have achieved a 2.488 Gb/s, 318 km repeaterless transmission without any fiber dispersion penalty through a nondispersion-shifted fiber in a direct detection system. The system was loss limited with a T-R power budget of 57 dB. Three key components enabled the authors to achieve this result: (1) a Ti:LiNbO/sub 3/ external amplitude modulator enabling a dispersion-free transmission, (2) erbium-doped fiber amplifiers increasing the transmitting power to +16 dBm, and (3) an erbium-doped fiber preamplifier enabling a high-receiver sensitivity of -4.1 dBm for 10/sup -9/ BER. To the author's knowledge, this result is the longest repeaterless transmission span length ever reported for direct detection at this bit rate. From the experimental results and a theoretical model, the authors identified the sources of the receiver sensitivity degradation from the quantum limit (-48.6 dBm) and estimated the practically achievable receiver sensitivity of approximately -44 dBm ( approximately -124 photons/bit) for 2.5 Gb/s optical preamplifier detection.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

8-Gb/s-130 km transmission experiment using Er-doped fiber preamplifier and optical dispersion equalization

The authors report an 8-Gb/s lightwave transmission system operating at 1.53- mu m wavelength through 130 km of single-mode fiber having a chromatic dispersion of zero at 1.3- mu m wavelength. A receiver sensitivity of -34.2 dBm (365 photons/bit) was achieved using an erbium-doped fiber preamplifier pumped at 980-nm wavelength. A sensitivity of -31.9 dBm (620 photons/bit) was reached by a preamplifier pumped at a 1480-nm wavelength. By employing a Ti:LiNbO/sub 3/ external modulator and a fiber Gires-Tournois interferometer to equalize fiber chromatic dispersion, the penalty for 130 km transmission was held to only 0.9 dB. >

Practical implementation of a highly sensitive receiver using an erbium-doped fiber preamplifier

A practical erbium-doped fiber preamplified direct detection receiver is demonstrated with which receiver input sensitivities of -46.5 dBm at 622 Mb/s and -40.7 dBm at 2.3 Gb/s have been achieved. There is no penalty from the transmission fiber Rayleigh backscattering. The bit error ratio measurements with 2/sup 23/-1 NRZ PRBS (pseudorandom bit sequence) show highly stable characteristics with no apparent error floor, owing to the polarization insensitivity of the preamplifier and to an active locking of the receiver optical filter. The tradeoff between preamplifier and avalanche gain is shown, and the influence of optical filter bandwidth and decision threshold setting is measured.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-sensitivity FSK signal detection with an erbium-doped fiber preamplifier and Fabry-Perot etalon demodulation

A report is presented on a 622-Mb/s optical transmission system with demodulation of alternate mark invert (AMI) encoded frequency shift keying (FSK) signals by a Fabry-Perot etalon. A 25-dB gain erbium-doped fiber preamplifier gave a receiver sensitivity of -40 dBm at 10/sup -9/ BER, which was improved to -44 dBm with the addition of a narrowband optical filter. The theoretical sensitivity of the preamplified receiver and the effect of the etalon on the amplified spontaneous emission beat noise are discussed and related to experiment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>