High-gain Erbium-doped Fiber Amplifier Research Articles

Short-pulsed Q-switched fiber laser using graphene oxide quantum dots based as saturable absorber

In this work, we report the experimental study of a Q-switched optical fiber laser based on graphene oxide quantum dots (GOQDs) as saturable absorber (SA). GOQDs are fabricated by carbonization and exfoliation electrospun polyacrylonitrile (PAN) fibers. The results of Fourier Transform Infrared Spectroscopy (FTIR) showed bands caused by the CHs and CO groups associated with the GOQDs. The Raman spectrum showed the typical G and D bands of GOQDs. The size of the GOQDs, calculated by Transmission Electron Microscopy (TEM) was 6 nm; additionally, by high resolution TEM (HRTEM), an interplanar distance of 0.19 nm corresponding to the (002) direction of the graphene oxide was calculated. The SA was achieved using the photodeposition technique of the GOQDs onto the core of a single-mode optical fiber. The nonlinear characterization (NLC) of the GOQDs was carried out using the P-scan technique with a high-gain erbium-doped fiber amplifier (EDFA) at a wavelength of 1550 nm. The obtained results showed a saturable absorption behavior with a value of β=−1.178x10−6(m/W) and a non-linear susceptibility of Im(χ(3))≈−1.573x10−7(esu). The experimental results of the SA, based on GOQDs as a switching device in a fiber laser, showed a typical behavior of a Q-switched laser by generating a pulsed emission at a wavelength of 1599 nm, a frequency from 2 to 16 kHz, and a maximum average output power of 1.3 mW.

Improvement of spectroscopic properties and luminescence of Er3+ions in phospho-tellurite glass ceramics by formation of ErPO4 nanocrystals

Er3+ doped phospho-tellurite glass was prepared by melt-quenching method. A limited partial crystallization of the glass samples was controlled by thermal annealing process in order to obtain a transparent glass-ceramic. The X-ray diffraction (XRD) patterns indicate the precipitation of nanocrystalline phases after heat treatment. A particular interest is devoted to the formation of ErPO4 nanoparticles (NPs) dispersed in the glassy host. The optical band gap (Eg) has been found to decrease from 3.37 to 2.75eV as the sample changes from glass to glass-ceramic. The Judd–Ofelt (JO) phenomenological intensity parameters (Ω2, Ω4, Ω6) have been estimated by means of the absorption spectrum. Radiative parameters of Er3+ ions have been predictedusing JO intensity parameters. Significant improvements of both the near infrared emission relative to the 4I13/2 → 4I15/2 transition and the corresponding luminescence lifetime were obtained after heat treatment. We show that an efficient excitation transfer occurs from the formed ErPO4 NPs to Er3+ ions. The Mc-Cumber method is used to calculate the absorption cross-section σa, the emission cross-section σe and the gain cross-section G(λ) relative to the 4I13/2 → 4I15/2 transition.Compared with other glass hosts, the results indicate that erbium doped phospho-tellurite glass-ceramic has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers (EDFA).

Enhancement of spectroscopic and luminescence properties of Er3+ doped tellurite glasses by adding P2O5 for lasing materials

Er3+-doped phosphor-tellurite glasses has been synthesized by conventional melting method. Results of differential scanning calorimetry (DSC) measurements indicate a good thermal stability of tellurite glasses. The DSC measurements show an improvement of thermal stability of glass hosts after adding P2O5. The structures of glasses were investigated by X-ray diffraction (XRD) and Raman spectroscopy to understand their dependence of structure on composition. Absorption spectrum from near infrared to visible was obtained and the Judd–Ofelt (J-O) intensity parameters (Ω2, Ω4, and Ω6) were determined. Spontaneous emission probabilities of some relevant transitions, branching ratio, and radiative lifetimes of several excited states of Er3+ have been predicted using intensity J-O parameters. Up-conversion luminescence characteristics, under 977 nm excitation wavelength, have been investigated at room and low temperature in these glasses. Intense green and red emissions from Er3+ centered at 534 nm, 548 nm and 660 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively, were simultaneously observed. The quadratic dependence of the up-conversion emission on the excitation power indicates that two-photon steps are involved for the three visible emission bands. The PL lifetimes is found to decrease in the temperature range 77–300K. Using the Mc-Cumber method, emission cross-section (σe), Absorption cross-section (σa), and gain cross-section (G(λ)) for the 4I13/2→4I15/2 transition, were calculated. By analyzing obtained data based to all advantages after adding P2O5, the tellurite glasses can be used as potential host material for developing optical amplifiers applied for 1.53 µm band broad and high-gain erbium-doped fiber amplifiers (EDFA).

Improvement of thermal and spectroscopic behavior of Er3+/Ce3+ co-doped tellurite glass for lasing materials

Tellurite glasses (TeO2–ZnO–Nb2O5) mono-doped Er3+ and co-doped Er3+/Ce3+ have been prepared using the melt-quenching technique. To evaluate the effect of Ce3+ on the structural, thermal stability of glass hosts and fluorescence properties of Er3+, X-ray diffraction patterns, Ftir spectra, differential scanning calorimeter curves, absorption spectra, fluorescence emission spectra, fluorescence lifetimes, up-conversion emission spectra of glass samples were measured and investigated. Using Judd–Ofelt theory, we calculated intensity parameters (Ω2, Ω4 and Ω6), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors and the quantum yield of luminescence for 4I13/2 → 4I15/2 transition. The co-doping with Ce3+ was effective on the suppression of up-conversion emission of Er3+ owing to the phonon-assisted energy transfer: Er3+:4I11/2 + Ce3+:2F5/2 → Er3+:4I13/2 + Ce3+:2F7/2 which contributed the effective enhancement of 1.53 µm fluorescence emission. The change in optical properties with the addition of Ce3+ ions have been discussed and compared with other glasses. Using the Mc Cumber method for the 4I13/2 → 4I15/2 transition, absorption cross-section, calculated emission cross-section, and gain cross-section values support that TZNEr1Ce1 glass is a potential material for developing broad-band and high-gain erbium-doped fiber amplifiers applied for 1.53 µm.

Growth of silver nanoparticles stimulate spectroscopic properties of Er3+ doped phosphate glasses: Heat treatment effect

The melt quenching technique was used to prepare Er3+ ion doped phosphate glasses containing silver nanoparticles (Ag NPs). The amorphous nature of the glass is confirmed by X-ray diffraction patterns. Homogeneous distribution of spherical Ag NPs was shown from the transmission electron microscopy (TEM). The EDX analysis shows the presence of Ag element. The DSC measurements indicate a relatively good thermal stability of the prepared glass samples. The characteristic surface plasmon resonance (SPR) band of Ag NPs was observed in the range of 420–570 nm in the optical absorption spectra. The SPR band stimulated by the presence of Ag NPs enhanced both the photoluminescence (PL) intensity and the fluorescence lifetime relative to the 4I13/2 → 4I15/2 transition of Er3+ ion. Ideal PL enhancement was obtained after 12 h of heat-treatment. The results indicate that there is a large influence of nucleation and growth of silver NPs on the optical and spectroscopic properties of the glass samples. The present results indicate that the glass heat-treated for 12 h has a good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers.

Surface plasmon resonance induced Er3+ photoluminescence enhancement in tellurite glass

The melt quenching method is used to prepare tellurite glasses co-activated with erbium ions and silver nanoparticles (Ag NPs). The glass samples are characterized by x-ray diffraction, UV-vis-NIR absorption, transmission electron microscopy (TEM) imaging, and photoluminescence spectroscopy. The XRD pattern shows no sharp peak indicating an amorphous nature of the glasses. The presence of Ag NPs is confirmed from TEM micrograph. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs in the 510–535 nm range. The J-O model has been applied to the room temperature absorption intensities of Er3+ (4f11) transitions to establish the so-called J-O intensity parameters: Ω2, Ω4, and Ω6. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) and branching ratios of the Er3+ transitions from the excited state J manifolds to the lower-lying J' manifolds. Intensified of 1.53 μm band is obtained for the sample containing 0.5 mol. % of AgNO3 (Ag0.5 glass) using for excitation a laser operating at 980 nm. The simultaneous influence of the Ag NPs → Er3+ energy transfer and the contribution of the intensified local field effect due to the silver NPs give origin to the enhancement of both the Photoluminescence (PL) intensity and the PL lifetime relative to the 4I13/2 → 4I15/2 transition, whereas the quenching is ascribed to the energy transfer from Er3+ ions to silver NPs. Based on the analysis of the temperature dependence of the PL intensity and decay time, we identified a weak back transfer process from Er to the glass host that makes the quenching of the PL intensity weak. Large magnitudes of calculated emission cross-section (σe), effective bandwidth (Δλeff), and bandwidth quality factor (FWHM × σe) relatives to 4I13/2 → 4I15/2 transition in Er doped Ag0.5 glass have been shown. They indicate that this glass sample has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers.

Silver nanoparticles enhanced luminescence properties of Er3+ doped tellurite glasses: Effect of heat treatment

Tellurite glasses doped Er3+ ions and containing Silver nanoparticles (Ag NPs) are prepared using melt quenching technique. The nucleation and growth of Ag NPs were controlled by a thermal annealing process. The X-ray diffraction pattern shows no sharp peak indicating an amorphous nature of the glasses. The presence of Ag NPs is confirmed from transmission electron microscopy micrograph. Absorption spectra show typical surface plasmon resonance (SPR) band of Ag NPs within the 510–550 nm range in addition to the distinctive absorption peaks of Er3+ ions. The Judd-Ofelt (J-O) intensity parameters, oscillator strengths, spontaneous transition probabilities, branching ratios, and radiative lifetimes were successfully calculated based on the experimental absorption spectrum and the J-O theory. It was found that the presence of silver NPs nucleated and grown during the heat annealing process improves both of the photoluminescence (PL) intensity and the PL lifetime relative to the 4I13/2 → 4I15/2 transition. Optimum PL enhancement was obtained after 10 h of heat-treatment. Such enhancements are mainly attributed to the strong local electric field induced by SPR of silver NPs and also to energy transfer from the surface of silver NPs to Er3+ ions, whereas the quenching is ascribed to the energy transfer from Er3+ ions to silver NPs. Using the Mc Cumber method, absorption cross-section, calculated emission cross-section, and gain cross-section for the 4I13/2 → 4I15/2 transition were determined and compared for the doped and co-doped glasses. The present results indicate that the glass heat-treated for 10 h has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers.

High-Gain, Low-Noise-Figure, and High-Linearity Analog Photonic Link Based on a High-Performance Photodetector

We report a high-gain, low-noise-figure, and high-linearity analog photonic link. The link combines a high-power and low-noise fiber laser, a Mach-Zehnder modulator, a high-gain erbium-doped fiber amplifier (EDFA), and a high-performance charge-compensated modified unitraveling-carrier photodiode. The critical characteristics of the photodiode include 16-GHz bandwidth, 200-mA saturation current, and >35 dBm third-order intercept point. In the link, low biasing is utilized to reduce the noise and maximize the signal-to-noise ratio, and an EDFA is used to provide sufficient optical input to the MUTC photodiode to ensure that the link can achieve high gain and high output RF power. The combination of high-power low-noise fiber laser and high-bandwidth high-power photodiode, we have enabled high gain (27.8 dB at 6 GHz and 24.5 dB at 12 GHz), low noise figure (4.7 dB at 6 GHz and 6.9 dB at 12 GHz), and high spur free dynamic range (>120 dB · Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> ) in the frequency range 6-12 GHz.

Silver nanoparticles enhanced 1.53 µm band fluorescence of Er3+/Yb3+ codoped tellurite glasses

The silver nanoparticles (NPs) was introduced into the Er3+/Yb3+ codoped tellurite glasses with composition of TeO2–ZnO to improve the 1.53µm band fluorescence of Er3+ and the thermal stability of glass host. The UV–Vis–NIR absorption spectra, 1.53µm band fluorescence spectra and fluorescence decaying curves, the differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images of glass samples were characterized to investigate the effect of silver NPs on the fluorescence properties of Er3+, thermal stability and structure behavior of glass host. It is shown that the Er3+/Yb3+ codoped tellurite glass emits intense 1.53µm band fluorescence with peak wavelength located at about 1532nm under the 980nm excitation. The introduction of silver NPs further improves the fluorescence intensity of Er3+ which is attributed to the enhanced local electric field effect induced by localized surface Plasmon resonance (LSPR) of silver NPs and the possible energy transfer from silver NPs to Er3+. An improvement by about 62% of 1.53µm band fluorescence intensity was found in the studied Er3+/Yb3+ codoped tellurite glass containing 0.5mol% amount of AgNO3. In addition, the thermal stability of glass host increases with the introduction of silver NPs while the glass structure maintains the amorphous nature. The present results indicate that the prepared Er3+/Yb3+ codoped tellurite glass with an appropriate amount of silver NPs has good prospect as a gain medium applied for 1.53µm band broad and high-gain erbium-doped fiber amplifiers (EDFAs).

Spectroscopic properties in Er3+/Yb3+ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3+/Yb3+ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3+ and Yb3+ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd—Ofelt theory, the oscillator strength was computed. The lifetime of 4I13/2 level (τm) of Er3+ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3+ was calculated by the McCumber theory. The spectroscopic properties of Er3+ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.

High-gain erbium-doped fiber amplifier incorporating a double-pass amplification technique as a preamplifier

We present a high-gain erbium-doped fiber amplifier to be utilized as a preamplifier. A double-pass amplification technique is used in the first-stage amplifier together with a tunable bandpass filter. The secondstage amplifier is a counter-pumped configuration and another tunable bandpass filter is utilized to filter out amplified spontaneous emission from the first-stage amplifier. This design is able to produce a high gain of 55.6 dB and a noise figure of 6.02 dB at 1530 nm with a signal power of −45 dBm. The receiver sensitivity measurement shows that the proposed amplifier improves the minimum detectable power from −33.7 to −40.8 dBm for a bit-error rate of 10−11 at 155 Mbps.

High-gain erbium-doped fiber amplifier incorporating a double-pass amplification technique as a preamplifier

We present a high-gain erbium-doped fiber amplifier to be utilized as a preamplifier. A double-pass amplification technique is used in the first-stage amplifier together with a tunable bandpass filter. The secondstage amplifier is a counter-pumped configuration and another tunable bandpass filter is utilized to filter out amplified spontaneous emission from the first-stage amplifier. This design is able to produce a high gain of 55.6 dB and a noise figure of 6.02 dB at 1530 nm with a signal power of −45 dBm. The receiver sensitivity measurement shows that the proposed amplifier improves the minimum detectable power from −33.7 to −40.8 dBm for a bit-error rate of 10−11 at 155 Mbps.

High gain erbium-doped fiber amplifier for the investigation of nonlinear processes in fibers

In this work we present a novel design of an optical amplifier with high gain elaborated from erbium-doped fiber (EDF). Its purpose is the amplification of low power pulses from laser diodes. The high power of the output pulses allows the investigation of nonlinear processes in optical fibers. The optical amplifier consists of two stages. The first stage uses a reflective configuration where a signal is amplified twice in the same EDF. The fiber Bragg grating (FBG) was the main element to reflect the signal. The second stage works as a high power amplifier. The input pulse has duration in the range of 1 to 50 ns, with wavelength equal to 1549.1 nm. With input pulse power of 1.5 mW, the amplifier provides 70 W in the output pulse. The gain obtained by the amplifier was 47 dB.

High‐gain triple‐pass amplification in two‐stage optical amplifier architecture

AbstractA new high‐gain Erbium‐doped fiber amplifier configured in a dual‐stage triple‐pass amplification scheme is presented. The first‐stage amplifier consists of double‐pass amplification in order to obtain high gain, while the second‐stage amplifier is single‐pass amplification. The optimum pump ratio of the first‐stage pump laser to the total pump power is found to be 30%. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 317–318, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20128

Extension of Semi-analytical Erbium-Doped Fiber Amplifier Model to Self-Saturation Regime

We show in this paper that the analytical erbium-doped fiber amplifier (EDFA) model presented by Jopson and Saleh in 1991 can be extended to the self-saturation regime, making it capable of simulating all practical EDFAs. We show that an Intel Pentium 66 based computer can calculate gain and noise figure for a counterdirectionally pumped self-saturated amplifier in <0.5 s when using the extended model as an effective noise bandwidth model. We compare the extended model with the effective noise bandwidth model presented by Giles and Desurvire in 1991 and show identical results. Finally we demonstrate very good agreement between measurements and simulations based on measured fiber data for both high-gain EDFAs (small-signal gain of 35 dB) and isolator EDFAs (small-signal gain of 43 dB) with deviations <1 dB on the gain and <0.7 dB on the noise figure.

Amplification of femtosecond pulses in a passive, all-fiber soliton source

We report a theoretical and experimental study of the amplification of femtosecond soliton pulses generated by a passively mode-locked fiber laser in a high-gain erbium-doped fiber amplifier (EDFA). Results on the spectral and temporal evolution of 450-fs soliton pulses propagating within an EDFA are presented. Power gains as high as 30 dB and the generation of sub-100-fs Raman colored solitons are observed. The results are found to be well described by the theoretical model presented.

Analytic modeling of high-gain erbium-doped fiber amplifiers

We describe an analytic method that calculates accurately (within a 1.5-dB discrepancy with numerical models) the gain of an erbium-doped fiber amplifier. Amplified spontaneous emission (ASE) is taken into account so that the gain of ASE-saturated erbium-doped fiber amplifiers is calculated properly. It is effective for wavelength multiplexing (several signals) and for different pumping schemes (copropagating or counterpropagating or both).

Performance of a lightwave system incorporating a cascade of erbium-doped fiber amplifiers

The photon-number distribution (PND) at the output of a cascade of erbium-doped fiber amplifiers (EDFAs), with coherent light at the input, turns out to be the noncentral-negative-binomial (NNB) distribution, even in the presence of intervening loss, provided that the normalized bandwidth is the same for all amplifiers. The probability of error (PE) for a cascade of several highgain EDFAs is essentially the same as that for a single EDFA. The performance of a sequence of postamplifiers is superior to that of a sequence of preamplifiers.

Detailed theoretical and experimental investigation of high-gain erbium-doped fiber amplifier

A full-scale numerical model for the erbium-doped fiber amplifier has been developed that incorporates realistic index and erbium-concentration profiles as well as the spectral distribution of amplified spontaneous emission (ASE). The high accuracy of the model is demonstrated by comparison with a comprehensive set of data, including gain, ASE, and pump power, obtained for a well-characterized Er-Al-doped fiber. An absorption-to-emission cross-section ratio of 1.0 was measured at the gain peak. Pumping at 654 nm, the excited state absorption was observed to be insignificant. A high gain of 39.6 dB was achieved in the experiment. >

Noise characteristics of erbium-doped fiber amplifier pumped at 980 nm

A noise figure of 2.9+or-0.4 dB, measured in a high-gain erbium-doped fiber amplifier for input signals in the range -35 to -15 dBm and for pump powers of >5.8 mW, is discussed. The spontaneous emission factor n/sub sp/ was 0.99+or-0.09 for input signals less than -15 dBm. These low figures are attributable to the optimized fiber design and the use of a pump wavelength of 980 nm, at which erbium operates as a true three-level system. These two factors contribute to the very low ( approximately 500 mu W) pump threshold seen in fiber, which permits nearly complete inversion to be achieved for the low pump powers employed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>