Modeling and Experiments of the Gain and Noise Figure for an Irradiated Erbium-Ytterbium Co-Doped Fiber Amplifier

It is crucial to study the effect of radiation on the fiber amplifier devices. In the present paper, the Erbium-ytterbium co-doped fiber amplifier (EYDFA) has been irradiated by a neutron beam of different doses for various exposure times from an Am-241/Be-9 neutron source. The gain and noise figure of the EYDFA have been calculated theoretically and recorded after and before the irradiation to test its performance under the effect of irradiation. In order to show the enhancement in the gain of the fiber amplifier devices, a comparison between the gain of the irradiated EYDFA and Erbium doped Fiber amplifier (EDFA) has been carried out. The calculated results by the proposed model are in good agreement with the experimental ones. It indicates that the gain of EYDFA deteriorates after being irradiated by a neutron dose. Moreover, the gain of irradiated EYDFA has been reduced to 13.8 dB at a dose of 720 Gy.

Influence of Input Pulse Durations on Properties of Er^(3+)/Yb^(3+) Co-doped DCFA

Based on propagation-rate equations, the influence of different input pulse durations on the properties of Er^3＋/Yb^3＋ co-doped double-clad fiber amplifier at dynamic equilibrium was analyzed. The change characteristic of output power sag with pulse duration and repetition rate was shown. Whether single or multichannel input pulses are amplified, the shorter the input pulse duration is, the smaller the power sags of output pulse will be. At low repetition rate, upper gain values（Gupper） of gain swing are almost the same for different input pulse durations, which tend to the small signal gain, but lower gain value（Glower） of short input pulse is larger than that of long input pulse. At highrepetition rate, lower gain value（Glower） approaches to upper gain value（Glower）.

Optimal design of Er/Yb co-doped fiber amplifiers with an Yb-band fiber Bragg grating

In this paper, Er/Yb co-doped fiber amplifiers(EYDFAs) with an Yb-band fiber Bragg grating(FBG) at the pump end to improve the performance of the amplifier is systematically studied. The influence of the reflectivity and center wavelength of the FBG along with the gain-fiber length on the performance of an EYDFA are numerically analyzed. The results show that the wavelength of the FBG has critical influence on the efficiency of the EYDFA,whereas the requirement to its reflectivity is relaxed. It is an effective and promising way to improve the efficiency of a high-power pumped EYDFA by introducing a suitable Yb-band FBG at the pump end. Based on the analysis of the underlying principles, suggestions for the practical design and possible further improvement strategies are also proposed.

Wideband Erbium-Ytterbium Co-Doped Phosphate Glass Waveguide Amplifier

A new '(?)' type of wideband erbium-ytterbium co-doped phosphate glass waveguide amplifier integrated with medium thin film filter is proposed, Average gain about 15.5dB between 1530nm and 1570nm with gain difference of below 2 dB is obtained.

High gain optical amplification and lasing performance of the Bi/P co-doped silica fiber in the O-band

In this Letter,the optical amplification characteristics of the home-made Bi/P co-doped silica fiber were systematically explored in the range of 1270–1360 nm.The maximum gain of 24.6 dB was obtained in the single-pass amplification device,and then improved to 38.3 dB in the double-pass amplification device for-30 dBm signal power.In addition,we simultaneously investigated the laser performance of the fiber with the linear cavity.A slope efficiency of 16.4%at~1313 nm was obtained with a maximum output power of about 133 mW under the input pump power of 869 mW at 1240 nm.As far as we know,it is the first laser reported based on the bismuth-doped fiber in China.

Transient Dynamics of Fluoride-Based High Concentration Erbium/Cerium Co-Doped Fiber Amplifier

We designed and evaluated a fluoride-based high concentration erbium/ cerium co-doped fiber amplifier. It is suitable for Metropolitan Area Networks due to faster transient, flatter (unfiltered) gain, smaller footprint and gain excursion than its silica-based counterpart.

Development of Bi/Er co-doped optical fibers for ultra-broadband photonic applications

Targeting the huge unused bandwidth（BW）of modem telecommunication networks,Bi/Er co-doped silica optical fibers（BEDFs）have been proposed and developed for ultra-broadband,high-gain optical amplifiers covering the 1150-1700 nm wavelength range.Ultrabroadband luminescence has been demonstrated in both BEDFs and bismuth/erbium/ytterbium co-doped optical fibers（BEYDFs）fabricated with the modified chemical vapor deposition（MCVD）and in situ doping techniques.Several novel and sophisticated techniques have been developed for the fabrication and characterization of the new active fibers.For controlling the performance of the active fibers,post-treatment processes using high temperature,γ-radiation,and laser light have been introduced.Although many fundamental scientific and technological issues and challenges still remain,several photonic applications,such as fiber sensing,fiber gratings,fiber amplification,fiber lasers,etc.,have already been demonstrated.

Theoretical study on erbium ytterbium co-doped super-fluorescent fiber source

Erbium ytterbium co-doped super-fluorescent fiber source （EYD-SFS） has been simulated by a theoret- ical model based on rate equations and power transfer equations. The output performances of four basic structures of EYD-SFS have been expressed, and it indicated that the DPF structure is a preferable structure. The dependence of output power, mean wavelength and bandwidth stability on the pump fiber length and the concentration of Er3＋ and Yb3＋ have also been studied. The results indicated with a proper doping concentration of Er3＋ and Yb3＋ of 6.0 × 10^26 ions/m3 and 1.0 × 10^27 ions/m3, the optimal gain fiber length is 3.6 cm. In this condition, good performances of DPF structure of EYD-SFS have been achieved.

50GeSe_2-25In_2Se_3-25CsI glass doped with Tm^(3+),Tm^(3+)/Ho^(3+) and Tm^(3+)/Er^(3+) foramplifiers working at 1.22 μm

Se-based chalcohalide glass of 50GeSe2-25In2Se3-25CsI was prepared. The thermal and optical characterizations revealed that this host was thermally and optically superior for practical applications. Strong emission centered at 1.22μm was observed in all Tm3＋ sin- gle-doped, Tm3＋/Ho3＋ and Tm3＋/Er3＋ co-doped samples with an excitation of 808 nm wavelength. The emission was attributed to the Tm3＋： 3Hs-→3H6 transition. The co-doping of Ho3＋ or Er3＋ largely broadened the width and slightly strengthened the intensity of the 1.22 gm emis- sion. The possible energy transfer processes and luminescence kinetics were figured. In addition, its potential application as the host material for novel optical amplifiers was discussed.

A 301 W narrow-linewidth in-band pumped Er:Yb co-doped fiber amplifier at 1585 nm and related modeling for dynamics study and optimization

To overcome Yb lasing,a kilowatt-level 1535 nm fiber laser is utilized to in-band pump an Er:Yb co-doped fiber(EYDF)amplifier.The output power of a 301 W narrow-linewidth EYDF amplifier operating at 1585 nm,with 3 dB bandwidth of 150 pm and M^(2)<1.4,is experimentally demonstrated.To the best of our knowledge,it is the highest output power achieved in L-band narrow-linewidth fiber amplifiers with good beam quality.Theoretically,a new ion transition behavior among energy levels for in-band pumping EYDF is uncovered,and a spatial-mode-resolved nonlinearityassisted theoretical model is developed to understand its internal dynamics.Numerical simulations reveal that the reduction in slope efficiency is significantly related to excited-state absorption(ESA).ESA has a nonlinear hindering effect on power scaling.It can drastically lower the pump absorption and slope efficiency with increasing pump power for in-band pumped EYDF amplifiers.Meanwhile,optimized approaches are proposed to improve its power to the kilowatt level via in-band pumping.

Design and Analysis of 120-μm Core Rod-Type Photonic Crystal Fiber for High Power 1.5-μm Band Amplifier

We report the design and analysis of a rod-type photonic crystal fiber with Er-Yb co-doped for the high power 1.5-μm band amplifier.The fiber structure is designed to be the 120-μm extreme large core diameter,300-μm inner cladding diameter,and 1.5-mm outer cladding diameter that ensure the single mode output during high power amplification.Both the continuous wave(CW) and pulsed amplification characteristics are analyzed based on the exact modeling and simulation under the designed geometry.The 4-mJ pulse energy and 400-kW peak power are obtained in theory,so the 1.5-μm band amplifier that achieves milojoule level pulse energy meanwhile keeping single mode is firstly designed.