Moo-Jung Chu

New pump wavelength of 1540-nm band for long-wavelength-band erbium-doped fiber amplifier (L-band EDFA)

A long-wavelength-band erbium-doped fiber amplifier (L-band EDFA) using a pump wavelength source of 1540-nm band has been extensively investigated from a small single channel input signal to high-power wavelength division multiplexing (WDM) signals. The small-signal gain coefficient of 1545-nm pumping among the 1540-nm band is 2.25 times higher compared to the conventional 1480-nm pumping. This improvement in gain coefficient is not limited by the pumping direction. The cause for this high coefficient is explained by analyzing forward- and backward-amplified spontaneous emission spectra. The gain spectra as a function of a pump wavelength suggest that a broadband pump source as well as a single wavelength pump can be used as a 1540-nm-band pump. In the experiment for high-power WDM signals, the power conversion efficiency for 256 WDM channel input is 48.5% with 1545-nm pumping. This result shows more than 20% improvement compared with the previous highest value for the L-band EDFA. Finally, the 1545-nm bidirectionally pumped EDFA is applied as a second stage amplifier in an in-line amplifier of an optical communication link with a 1480-nm pumped first stage EDFA, in which the input power of the second-stage EDFA is +2.2 dBm. The power conversion efficiency yields a 38% improvement without noise figure degradation compared with the case of 1480-nm pumping.

High-gain coefficient long-wavelength-band erbium-doped fiber amplifier using 1530-nm band pump

A 1530-nm band has been studied as a pump wavelength for the long-wavelength-band erbium-doped fiber amplifier (L-band EDFA). The pump source is built using a tunable light source and cascaded conventional-band (C-band) EDFA. The L-band EDFA uses a forward pumping scheme. Within the 1530-nm band, the 1545-nm pump demonstrates 0.45-dB/mW gain coefficient, which is twice better than that of conventional 1480-nm pumped EDFA. The noise figure of the 1530-nm pump is at worst 6.36 dB, which is 0.75 dB higher than that of the 1480-nm pumped EDFA. Such high-gain coefficient indicates that the L-band EDFA consumes low power.

Transient effects and gain-control method in low-noise dispersion-compensating hybrid fiber amplifier

Transient effects in low-noise dispersion-compensating hybrid fiber amplifier (DC-HFA) are presented to show the combined dynamics of erbium-doped fiber amplifier and fiber Raman amplifier. Transient features in surviving signal channel are analyzed with numerical simulation in each stage of DC-HFA. A gain-control method that utilizes the transit time of dispersion-compensating fiber is suggested and it has the advantages of enough time for the gain-control electronics and lower noise figure in surviving channels.

Distributed fiber Raman amplifiers with localized loss

Backward pumped C- and L-band distributed fiber Raman amplifiers are described, where discrete losses from 0-8 dB were added at various positions to examine the effect of localized loss. Below 3-dB additional loss, the overall optical performance degraded similarly, regardless of loss position in a hybrid Raman and erbium-doped fiber amplifier. Above 3 dB, the performance degradation worsened as the loss position became closer to the signal output. The spectral shape change of the fiber output against loss variation was made tolerable within /spl plusmn/0.4 dB simply by balancing the output power of L band with that of C band, unless the loss was close to pump input. The tolerance provides design flexibility for hybrid optical amplifiers and allows the use of fixed gain-flattening filters.

Simple numerical characterization of double Rayleigh scattering noise in fiber Raman amplifiers

We proposed a method to calculate the double Rayleigh scattering (DRS) noise easily by separating signal part and noise part in signal evolution equations of fibre Raman amplifiers (FRAs). The result was compared with constant gain approximation and it shows reasonable agreements. The DRS noises were compared in cases of forward pumping and backward pumping. The DRS noise of each channel in WDM transmission was calculated and it would be helpful to estimate the power penalty resulted from the DRS noise in long-haul WDM transmission.

Transient effects in low-noise dispersion-compensating hybrid fiber amplifier

Transient effects in low-noise dispersion-compensating hybrid fiber amplifier (DC-HFA) are presented to show the combined dynamics of EDFA and Raman amplifier. A gain control method is demonstrated in DC-HFA by numerical simulation, and the advantages of the method are discussed.

Investigation of pump wavelength dependence of long-wavelength-band erbium-doped fiber amplifier using 1530 nm-band pump for WDM amplification

The 1530 nm band was investigated as a new pump wavelength band of long-wavelength-band Er/sup 3+/-doped fiber amplifier and compared with the conventional 1480 nm band. The gain coefficients of 1530 nm band pumping were two times greater than those of 1480 nm pumping.

Characteristics of long-wavelength-band EDFA pumped by 1.53 /spl mu/m band

Summary form only given. The dependence of pump wavelength for the amplification characteristics of a Er/sup 3+/-doped fiber amplifier (EDFA) has been reported for 0.8, 0.98, or 1.48 /spl mu/m band, to date now most of long-wavelength-band (L-band) EDFA are using these pump bands. In this paper, 1.53 /spl mu/m band is proposed and intensively investigated as new pump wavelength of L-band EDFA for the fist time. Power conversion efficiency (PCE), gain coefficient and noise figure (NF) for pumping efficiency were measured and compared with 1.48 /spl mu/m pumped L-band EDFA.