Optical Fiber Amplifiers Research Articles

A monolithic microlens for an ytterbium-doped microstructured optical fiber amplifier

Ytterbium-doped microstructured optical fibers have many advantages for fiber amplifiers. Due to air-hole structures in the cladding of ytterbium-doped microstructured optical fibers, high-power microstructured optical fiber laser systems require stricter treatment of the fiber end than conventional ytterbium-doped double-cladding fiber laser systems. Here, we fabricated a fiber microlens in an ytterbium-doped double-cladding microstructured optical fiber for a fiber amplifier by CO2-laser fusion. The microlens can combine the end-cap scheme, pump coupling and beam shaping. This end face processing technology is useful for high mechanical stability, good reproducibility and miniaturization of laser systems.

Transmission Performance Comparison of 16*100 Gbps Dense Wavelength Division Multiplexed Long Haul Optical Networks at Different Advance Modulation Formats under the Influence of Nonlinear Impairments

Abstract Higher spectral efficiency and data rate per channel are the most cost-effective approaches to meet the exponential demand of data traffic in optical fiber network communication system. In this paper, diverse modulation formats are analyzed for Dense Wavelength Division Multiplexed system at 100 Gbps * 16=1600 Gbps data rates. The performance analysis of proffered system for Non-Return to Zero, Return to Zero, Carrier- Suppressed Return to Zero and Duo binary RZ with duty cycle 0.5 to 0.7 ranges like modulation formats are considered to find optimum modulation format for a 100 Gbps bit rate per channel optical fiber transmission network system. The simulations are analyzed for different values of input power, length of fiber, nonlinear refractive index, nonlinear dispersion and nonlinear effective area for all above mentioned modulation formats with spacing 100 to 250 GHz. to evaluate the effect of modulation format Fiber Bragg Gratting, optical fiber amplifier and Dispersion Compensation Fiber dispersion compensation techniques are enacted on this proposed optical network system.

Effect of neutron irradiation on the optical properties of PMMA/RhB used in optical fiber amplification

The structural and optical properties of the neutron irradiated PMMA doped by 5 wt% RhB have been investigated. Fourier transform infrared analysis showed a significant variation in the polymer’s main chain. Moreover, the linear and nonlinear optical properties of the doped samples, both pre and post irradiation were studied. The results showed that the refractive indices and energy gaps of the examined samples were increased at a neutron dose of 1.5 kGy by about 8% and 7%, respectively. The results gave a good indication in predicting the gain degradation of the polymer optical amplifier when exposed to a low dose irradiation.

Modeling degraded performance metrics of optical amplifiers under radiation

Gain, noise figure (NF), and output power are considered the common performance metrics of an optical fiber amplifier. With an increasing interest of space industry in developing technologies for satellite-ground and intersatellite communication in the optical band, the EDFA (erbium doped fiber amplifier) is needed as power amplifier in space to compensate attenuation and insertion losses between the building blocks of the architecture. There is very little research on modeling the degradation mechanisms of typical commercial fibers, specifically on the NF and output power metrics, that requires knownledge of the insertion losses at the entrance of the fiber for both the pump and the signal wavelengths λp and λs. In this brief report we propose that the noise figure and output power trends can be extrapolated from a semi-empirical model for the insertion losses proved at high and low dose rates at two different temperatures. The results show reasonable trends that a common offthe shelf EDFA can present in co-propagating configuration on the NF and output power under several doses at low and high rates. The radiation losses using non-hardened fiber show sustainable attenuation levels in dB that can possibly allow employing this off-the shelf fibers in CubeSats or small satellites without the need of special radiation insulation. It is further supported with theoretical data that the temperature factor can affect more the EDFA degradation in space than the radiation itself, imposing limits on the temperature control of commercial satellites using this photonics.

Near-infrared and upconversion luminescence of Tm3+ and Tm3+/Yb3+-doped oxyfluorosilicate glasses

Oxyfluorosilicate glasses-doped with different concentrations of Tm3+ and Tm3+/Yb3+ ions have been synthesized and characterized their absorption, photoluminescence, luminescence decay and upconversion properties. The Judd-Ofelt intensity parameters have been obtained from the absorption spectrum of Tm3+ single-doped glass and are in turn used to calculate radiative properties such as transition probabilities, branching ratios and lifetimes for the fluorescent levels of Tm3+ ions. Visible and near-infrared emission spectra of Tm3+ and Tm3+/Yb3+-doped glasses have been measured under 473 nm laser excitation. The quenching of emission intensities at higher concentrations of Tm3+ ions has been found to be due to cross-relaxation mechanisms. The Tm3+/Yb3+ co-doped glasses show upconverted emissions under 975 nm laser excitation. The mechanism of upconversion has been explained based on the pump power dependence of upconversion luminescence. The results reveal that the co-doped glasses are promising for optical fiber amplifiers operating at the relatively low-loss wavelength regions.

Optical fiber amplifier for quantitative and sensitive point-of-care testing of myoglobin and miRNA-141

A simple, sensitive, quantitative point-of-care testing (POCT) was developed integrating enzyme-linked DNA supersandwich amplification with optical fiber amplifier. The point-of-care (POC) assay can work in both “Turn-off” mode and “Turn-on” mode. Using myoglobin (Myo) and miRNA-141 as the model biomarker, as low as 0.5 nM Myo and 10 pM miRNA-141 could be detected. More importantly, the optical fiber amplifier, which was used as signal readout, exhibited low-cost, small size, rapid response, and easy operation. Although it did not need large equipment and professional technical personnel, the assay was successfully applied to detect Myo and miRNA-141 in 40% human serum. Since the entire process of the strategy could be done directly in the centrifugal tube, requiring a few easy steps, it showed great potential application for early diagnosis in the world, especially in developing countries or remote regions. This work provided a new avenue for developing the portable and sensitive biosensor.

Wideband optical fiber amplifier with short length of enhanced erbium–zirconia–yttria–aluminum co-doped fiber

A wideband optical amplifier is demonstrated by using an enhanced Zirconia–Yttria–Aluminum erbium doped fiber (Zr-EDF) with a total length of 3.5 m as gain media, in double-pass parallel configuration. At −10 dBm input signal, the proposed amplifier produces a flat gain of 17.1 dB with gain fluctuation less than 1.5 dB within wavelength region from 1525 to 1600 nm. The noise figure is maintained below 10 dB within the flat gain region.

On the Enlargement of the Emission Spectra from the 4I13/2 Level of Er3+ in Silica-Based Optical Fibers through Lanthanum or Magnesium Co-Doping

Improving optical fiber amplifiers requires the elaboration and use of new materials and new compositions. In this sense, we prepared erbium-doped optical fiber samples that were co-doped with magnesium or lanthanum by gradual-time solution doping. Doping concentrations and thermal processes induce the formation of nanoparticles. The effect of lanthanum and magnesium contents on the width of the spontaneous emission of the 4 I 13 / 2 level of Er 3 + was characterized in the nanoparticle-rich fiber samples. For that purpose, the width was characterized by the effective linewidth and the full-width at half-maximum (FWHM). The results indicate the robustness of the effective linewidth to strong variations in the intensity profiles of the 4 I 13 / 2 spontaneous emission. Increasing the doping concentrations of both magnesium and lanthanum increases the FWHM and the effective linewidth, along with optical losses. Results show that the fabrication of nanoparticle-rich optical fibers through lanthanum or magnesium doping induces an FHWM broadening of 54% and 64%, respectively, or an effective linewidth broadening of 59% (for both elements) while maintaining a transparency that is compatible with fiber laser and amplifier applications.

Manufacturing of Volumetric Glass–Based Composites with Single‐ and Double‐QD Doping

AbstractQuantum dot (QD)‐based light‐emitting materials are gaining increased attention because of their easily tunable optical properties desired for various applications in biology, optoelectronics, and photonics. However, few methods can be used to manufacture volumetric materials doped with more than one type of QD other than QD‐polymer hybrids, and they often require complicated preparation processes and are prone to luminescence quenching by QD aggregation and separation from the matrix. Here, simultaneous doping of a volumetric glass‐based nanocomposite with two types of QDs is demonstrated for the first time in a single‐step process using the nanoparticle direct doping method. Glass rods doped with CdTe, CdSe/ZnS, or co‐doped with both QDs, are obtained. Photoluminescence and lifetime experiments confirm temperature‐dependent double emission with maxima at 596 and 720 nm with mean lifetimes up to 16 ns, as well as radiative energy transfer from the short wavelength–emitting QDs to the long wavelength–emitting QDs. This approach may enable the simple and cost‐efficient manufacturing of bulk materials that produce multicolor luminescence with cascade excitation pumping. Applications that could benefit from this include broadband optical fiber amplifiers, backlight systems in LCD screens, high‐power LEDs, or down‐converting solar concentrators used to increase the efficiency of solar panels.

Investigation of Multiwavelength Laser Performance based on Temperature Variation of PMF and different SOAs

We demonstrated a multiwavelength performance based on bidirectional Lyot filter at different temperature of polarization maintaining fiber (PMF) and semiconductor optical amplifiers (SOAs). The multiwavelength fiber laser (MWFL) based on bidirectional Lyot filter is not investigated thoroughly on its channel spacing tunability due to birefringence change. A channel spacing of this MWFL is tunable due to birefringence change of the PMF. The birefringence value of is changed by heating the PMF, that leads to narrower channel spacing. From the experimental data, the temperature coefficient based on PMF length of 53.2 m and 10.6 m is 0.49 ×10 -3 nm/°C and 1.35 ×10 -3 nm/°C, respectively, thus shorter PMF is more sensitive to temperature. We also investigated the multiwavelength performance at different SOAs. When the SOA from Qphotonics is changed to the SOA from Alphion, the extinction ratio is reduced from 15 dB to 8 dB. In terms of flatness value, the Qhotonics’s SOA has a flatter multiwavelength spectrum with only 1 dB of peak power difference from 1538 nm until 1541 nm as compared to 2.5 dB when using Alphion’s SOA.

Sensitizing effect of Yb3+ ions on photoluminescence properties of Er3+ ions in lead phosphate glasses: Optical fiber amplifiers

The Er3+/Yb3+-codoped lead phosphate (PPbKANErYb) glasses have been prepared by using melt quenching technique and characterized through spectroscopic studies such as absorption, emission, decay and upconversion measurements. An intense near-infrared (NIR) emission at 1.53 μm was observed which has been explained based on the effective energy transfer from Yb3+ to Er3+ ions. The absorption (4I15/2 → 4I13/2) and emission cross-section (4I13/2 → 4I15/2) of 1.53 μm emission band was calculated and found to be of the order of 6.76 × 10−21 and 7.9 × 10−21cm2, respectively, by using the McCumber theory. The PPbKANErYb glasses exhibit higher luminescence intensity (more than 3 times) and full width at half maxima (55 nm) compared to 1.0 mol % Er3+ singly doped glass (50 nm). All the decay curves of the 4I13/2 level exhibited single exponential nature and the lifetimes increased (1760, 1776, 1942 and 2830 μs) with the increase of Yb2O3 (0.5, 1.0, 2.0 and 3.0 mol %) concentration. Intense red band at 670 nm corresponding to 4F9/2 → 4I15/2 transition and green emission bands at around 530 and 555 nm corresponding to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2, transitions, respectively, have been observed under the excitation of 980 nm. The intensity of the upconversion emissions is found to be increased with the increase of Yb3+ ion concentration and its mechanism have been explained. The luminescence decay curves of the 4S3/2 → 4I15/2 upconversion luminescence of Er3+/Yb3+ codoped PPbKAN glasses under the infrared excitation of 980 nm have been evaluated. The results reveal that the investigated glasses might be potential candidates for optical fiber amplifiers/laser sources at 1.55 μm band.

Observation and practical implications of nano‐scale phase separation in aluminosilicate glass optical fibers

AbstractThis communication provides direct experimental evidence of nano‐scale phase separation in as‐fabricated high‐alumina content (>25 mole percent) optical fibers, experimentally corroborating recent molecular dynamic simulations. In addition, previously incorrect assumptions of glass homogeneity in low‐loss binary aluminosilicate optical fibers are corrected and practical implications for such intrinsically low nonlinearity glass optical fiber amplifiers and lasers are discussed.

Facile preparation of plasmon enhanced near-infrared photoluminescence of Er3+-doped Bi2O3-B2O3-SiO2 glass for optical fiber amplifier

This work reports the plasmon enhanced near-infrared emission from Er3+-doped Bi2O3-B2O3-SiO2 glass prepared by conventional melt-quenching method. The silver nanoparticles (NPs) were introduced into glass host as starting constituent not in the form of silver univalent ions, avoiding the complex energy transfer between Ag+ and Er3+. TEM images analysis reveal the homogeneous distribution of almost spherical Ag NPs with average diameter ~6 nm in amorphous glass. Surface plasmon resonance (SPR) band was observed around 495 nm. Interestingly, the near-infrared emission intensity assigned to Er3+:4I13/2→4I15/2 transition undergoes significant enhancements up to 2 times. The peak emission cross section at 1.5 µm is estimated to be 7.3 × 10–21 cm2 on the basis of Fuchbauer–Ladenburger equation. Furthermore, the measured lifetime of Er3+:4I13/2 energy state is prolonged from 1.72 ms to 1.85 ms with the gradual increasing Ag NPs. The silver nanoparticles enhanced near infrared luminescence from bismuth glasses have potential application for optical fiber amplifier.

Study of the energy transfer process in rare earth-doped silk fibroin for future application in luminescent compounds

The use of rare earth (RE)-doped materials in photonics; e.g., in solid-state lasers in the UV–vis NIR spectral region, in light emitting devices, and in fibers for optical amplifiers and data storage systems, is well known. Combining the mechanical and optical properties of silk fibroin (SF) with the multifunctionality of rare earth ions could be an interesting strategy to develop new, distinguished photonic devices. For this reason and given that no studies about light emission in RE-doped silk fibroin exist, here we present an innovative approach to develop photonic devices based on SF doped with RE ions, and we employ europium ion as a structural probe in a RE-doped composite SF matrix to obtain systems with better emission parameters. To this end, we prepared self-supported films consisting of RE-doped SF. The Bombyx mori SF bears aromatic amino acids, such as Tyrosine (Tyr) and Tryptophan (Trp), which display fluorescent behavior. These amino acids can function as fluorescent probes of physicochemical properties. In the presence of RE ions, these amino acids can act as sensitizer in energy transfer processes. Our results revealed RE ion emission associated with an antenna effect elicited by the aromatic amino acids. We verified distinct photophysical properties for different RE ions. To understand the process, we determined the triplet state of Trp in SF, which helped to describe the energy process. The energy of the Trp triplet state allowed quite efficient energy transfer from Trp to the Tb3+ ion. In conclusion, this research work improved our understanding of the mechanism of RE ion excitation in SF matrix. The present results will support future work on the development of new photonic systems.

Optical Properties and Bismuth Redox in Bi-Doped High-Silica Al–Si Glasses

Due to their unique optical properties, Bi-doped glasses have a great potential for the development of new tunable laser sources. Particular attention is given to high-silicate Bi-doped glasses as active media for fiber lasers and optical amplifiers, capable to operate at the second and the third near-infrared (NIR) transparency windows. Although significant practical advances have been achieved in this area, the origin of the NIR luminescence remains unclear. In the present paper, a set of glasses 95.5SiO2–4.5Al2O3–xBi2O3 (x = 0; 0.005; 0.01; 0.05; 0.1; 0.2) were synthesized using a conventional melt-quenching technique and investigated using a multiscale approach. Variation of the NIR emission was correlated with the change of other optical properties, structure and bismuth redox, supported by fluorescence/absorption, Raman, and XANES experimental studies, respectively. It was found that redox of bismuth shifted toward the formation of more reduced Bi species with the decrease of the dopant level. Based...

Tapered optical fiber deposited with PbS as an optical fiber amplifier based on atomic layer deposition

Optical properties of tapered optical fiber deposited with PbS are investigated, which is deposited based on atomic layer deposition technique with Pb(tmhd)2 and H2S as Pb and S precursors. After deposition, morphology of PbS thin film is characterized by a scanning electron microscope, and the composition is confirmed by X-ray photoelectron spectroscopy and energy dispersive spectrum. Raman spectrum shows a typical peak at 204 cm − 1, which is assigned to the influence of the PbS structure, and it further reveals that PbS is deposited on the surface of the tapered optical fiber successfully. With a 980-nm pump laser diode, tapered optical fiber deposited with PbS applied to fiber amplifier exhibits a wide band optical gain at 1550 nm with the largest gain of 5.6 dB.

Compact and flat-gain fiber optical amplifier with Hafnia-Bismuth-Erbium co-doped fiber

For the first time, we demonstrated a compact Erbium-doped fiber amplifier (EDFA) using a newly developed Hafnia Bismuth Erbium co-doped fiber (HBEDF) as a gain medium. The HBEDF was fabricated using a modified chemical vapor deposition process in conjunction with solution doping technique. The fiber has high doping levels of Erbium ion of 12,500 wt ppm through incorporation of Hafnium and Bismuth ions, which prevents the clustering effect. At the input signal power of −10 dBm, a flat gain of 10.9 dB is obtained from the wavelength region of 1525 to 1565 nm with a gain variation of less than ± 0.5 dB. The noise figure is maintained below 4.4 dB at the flat-gain region. The proposed amplifier has the potential applications in dense wavelength division multiplexing communication system due to its simplicity and compact design.

Effect of pump parameters on the emission of PbSe quantum dot-doped optical fiber considering Auger recombination

The deficiency for quantum dots (QDs) used as optical amplified medium (such as QD-doped fibers) is nonradiative Auger recombination based on multiple exciton state, which is related to pump power, pump frequency, and pump wavelength. Thus, the Auger recombination lifetime was introduced in the existing three-level system, further the emission of PbSe QD-doped optical fiber as a function of pump parameters mentioned above was simulated in order to maximize emission intensity and optical gain. The emission intensity increased first and then saturated with the pump power, showing good agreement with the experimental data. An optimal pump power maximizing the emission intensity was observed, which is distinguished from the non-Auger decay-result that the emission intensity increased with the pump power in a linear way. The emission intensity increased with the increasing pump frequency (from 4 to 10 × 10 4 Hz). In addition, 532-nm pump light was confirmed to enhance the output intensity compared to the other longer wavelengths. The relationship between emission intensity and pump fluence is similar to that of the experimental data. The maximal optical gain of 11.5 dB was obtained. The threshold pump power decreased with the increasing pump frequency, in which situation, larger pump power was needed to achieve the optical gain saturation. This research might be a theoretical basis for QD-doped optical fiber amplifiers and lasers.

A Flat-Gain Double-Pass Amplifier with New Hafnia-Bismuth-Erbium Codoped Fiber

An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber (HBEDF) as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 ppm. At the optimum length of 0.5 m, the HBEDF amplifier (HBEDFA) achieves a flat gain of 26 dB with a gain variation of less than 1.5 dB within a wavelength region from 1530 to 1560 nm when the input signal and pump power are fixed at −30 dBm and 140 mW, respectively. On the other hand, at the input signal power of −10 dBm, the HBEDFA also achieves a flat gain of 14.2 dB with a gain variation of less than 2.5 dB within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier, the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of −30 dBm, the gain improvements of 6.2 dB and 4.8 dB are obtained at 1525 nm and 1540 nm, respectively.

Theoretical Comparison of Noise Characteristics in Semiconductor and Fiber Optical Amplifiers

Characteristics of the intensity noise, the phase noise, the frequency noise, and the spectral linewidth in the semiconductor optical amplifier (SOA) and the erbium doped fiber amplifier (EDFA) were theoretically examined with a unified analyzing manner. Quantum mechanical fluctuations associating with the optical amplification and the spontaneous emission were taken into account as noise sources on the traveling optical wave. Quantitative calculated results are obtained. As general features, the SOA reveals higher noise than the EDFA, due to larger inclusion of the amplified spontaneous emission, larger value of the optical absorption and larger fluctuation of the injected electron density. However, the SOA has an exceptional feature to suppress the relative intensity noise (RIN) of the output light below the input RIN level under suitable operating condition. The spectrum linewidth hardly increases in both the SOA and the EDFA under linear operation.