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We propose a four-wave mixing (FWM) crosstalk measurement method for a signal with 50 GHz spaced wavelength channels in a highly doped L-band erbium-doped fiber amplifier (EDFA). The method uses the crosstalk measured by using a signal with 100 GHz spaced wavelength channels. This approach is based on analyses of the channel spacing dependence of FWM signal generation and the effect of the gain evolution of each signal channel along the EDF during FWM signal generation at a specific frequency. It is shown that reducing the channel spacing from 100 to 50 GHz has little impact on the efficiency of FWM generation if the gain evolution is the dominant term in FWM generation. It is also shown that the contributing ratio of the gain evolution of each channel is almost the same for the two signals. These results enable us to develop a measurement method for estimating the FWM crosstalk in an L-band EDFA applied to a wavelength-division multiplexing system with a 50 GHz spaced signal by using a 100 GHz spaced signal and a compensation factor. The validity of the measurement method is successfully demonstrated experimentally. [ABSTRACT FROM PUBLISHER]

We simulated the differential modal gain (DMG) property of WDM amplification characteristics for a ring-core erbium-doped fibre (RC-EDF) to clarify the possibility of an RC-EDF being used as a three- to five-signal LP-mode amplification medium. The authors defined two parameters, DMGYY-XX and WDGXX. The former and the latter are the difference between the gains of the LPXX mode and the LPYY mode at the shortest wavelength, and the gains of the LPXX mode at the shortest and longest wavelengths of WDM signal channel, respectively. XX and YY indicate the signal LP mode number. The authors present contour diagrams of the maximum DMGYY-XX and maximum WDGXX on the allowable three- to five-signal LP-mode areas of the RC-EDF. They confirm that it is possible to realise the amplification with a maximum DMGYY-XX of ≤2 dB, ≤1 dB, and about 2 dB for the 3, 4, and 5-LP modes and a maximum WDGXX of ≤ 1 dB for the three- to five-LP mode. The authors found that it is possible to realise an amplifier for 3-5 LP modes that operate with a relatively low DMG by using RC-EDF. [ABSTRACT FROM AUTHOR]

We report an S-band erbium-doped fiber amplifier (EDFA) with a multistage configuration in terms of its design, gain, and noise characteristics for various pump powers and input signal powers, the temperature dependence of the gain spectra, and gain tilt compensation for changes in input signal power and temperature change. We show that there is a tradeoff between low noise and efficiency in the S-band EDFA and describe the development of an S-band EDFA with a flattened gain of more than 21 dB and a noise figure of less than 6.7 dB. We also show that there is a change in the gain spectra with changes in the pump power and input signal power that is different from that observed in C- and L-band EDFAs, and that our EDFA has a temperature-insensitive wavelength. Furthermore, we develop a gain tilt compensated S-band EDFA that can cope with changes in input signal power and temperature. [ABSTRACT FROM PUBLISHER]

Schemes are proposed for the highly reliable gain control of erbium-doped fiber amplifiers (EDFAs) and for power monitoring to detect faults in wavelength-division-multiplexing (WDM) networks. These schemes employ one WDM channel (a control channel). The EDFA gain and output power levels are controlled by monitoring the control channel power that is automatically controlled and stabilized in the node. This prevents the uncontrolled EDFA operation that might result from any serious change in the control channel power. The use of a power stabilized control channel for power monitoring makes it possible to detect transmission system faults correctly because the monitoring of the control channel power is unaffected by the amplified spontaneous emission (ASE) generated in the EDFA. We also report experimental results on the dependence of the transient response of the EDFA gain and output power on the signal channel power and channel number input into the EDFA, when the power of the control channel changes due to problems with its light source. Numerical calculation of the gain transience explains the experimental results. [ABSTRACT FROM PUBLISHER]

This paper describes the amplification characteristics of gain-flattened Er3+-doped fiber amplifiers (EDFAs) by using 0.98-μm and 1.48-μm band pumping for a 1.58-μm band WDM signal. Silica-based Er3+-doped fiber (S-EDF) and fluoride-based Er 3+-doped fiber (F-EDF) have gain-flattened wavelength ranges from 1570 to 1600 nm and from 1565 to 1600 nm, respectively, and exhibit uniform gain characteristics with gain excursions of 0.7 and 1.0 dB, and the figure of merit of the gain flatness (gain excursion/average signal gain) of 3 and 4.3%, respectively, for an eight-channel signal in the 1.58-μm band. We show that 1.48-μm band pumping has a better quantum conversion efficiency and gain coefficient, and that 0.98-μm band pumping is effective for improving the noise characteristics. We also show that the EDFAs consisting of two cascaded amplification units pumped in the 0.98-μm and 1.48-μm bands are effective in constructing low-noise and high-gain 1.58-μm band amplifiers [ABSTRACT FROM PUBLISHER]

Proposed is a multi‐core fibre amplification method that can reduce crosstalk, in which the optical amplified signals in two adjacent cores propagate in opposite directions. By employing the proposed method, confirmed is a crosstalk improvement of more than 4 dB using the outer six cores of a seven‐core erbium‐doped fibre. [ABSTRACT FROM AUTHOR]

This letter investigates the feasibility of an erbium-doped tellurite fiber amplifier (EDTFA) with a 1581- to 1616-nm amplification band for a wavelength-division-multiplexing transmission system in the L-band that employs dispersion-shifted fiber (DSF). A 10-Gbit/s, 40-channel-transmission from 1581 to 1616 nm in the L-band, where EDTFA's are employed as a post-amplifier, repeaters, and a pre-amplifier, is error-free through a 320-km DSF. The EDTFA can increase both the transmission capacity and the allowable maximum input power launched into a DSF. [ABSTRACT FROM PUBLISHER]

A low-noise broad-band EDFA with a seamless amplification band in both the C- and L-bands is successfully developed by using erbium-doped tellurite fibers. This EDFA exhibits a broad amplification bandwidth of 70.8 nm (from 1532.7 to 1603.5 nm) with a gain excursion of less than 1.5 dB, an average gain of 24.3 dB, and a noise figure of less than 6 dB (less than 5.3 dB for extracting the insertion loss of the input end). [ABSTRACT FROM PUBLISHER]

The differential modal gain (DMG) in a few-mode erbium-doped fibre amplifier (FM-EDFA) is successfully improved by employing a ringcore FM erbium-doped fibre (RC-EDF). The DMGs between LP01 and LP11 mode signals in the FM-EDFA with the RC-EDF are 1.8 and 1.6 dB for LP01 and LP11 mode pumping, respectively, whereas those in a FM-EDFA with a conventional step-index FM EDF are 9.2 and 6.1 dB, indicating 7.4 and 4.5 dB DMG improvement for LP01 and LP11 mode pumping, respectively. [ABSTRACT FROM AUTHOR]

An inter-core crosstalk measurement method in a multi-core erbiumdoped fibre amplifier that uses a single-wavelength signal with multiple intensity tones is investigated. Its feasibility is confirmed and the output signal power dependence of the crosstalk values for the same signal gains between cores is successfully characterized. [ABSTRACT FROM AUTHOR]

An inter‐core crosstalk measurement method in a multi‐core erbium‐doped fibre amplifier that uses a single‐wavelength signal with multiple intensity tones is investigated. Its feasibility is confirmed and the output signal power dependence of the crosstalk values for the same signal gains between cores is successfully characterised. [ABSTRACT FROM AUTHOR]