Erbium-doped Optical Fiber Research Articles

High-Sensitivity Differential Helmholtz Photoacoustic System Combined with the Herriott Multipass Cell and Its Application in Seed Respiration.

A highly sensitive photoacoustic detection system using a differential Helmholtz resonator (DHR) combined with a Herriott multipass cell is presented, and its implementation to sub-ppm level carbon dioxide (CO2) detection is demonstrated. Through the utilization of erbium-doped optical fiber amplifier (EDFA), the laser power was amplified to 150 mW. Within the multipass cell, a total of 22 reflections occurred, contributing to an impressive 33.6 times improvement in the system sensitivity. The normalized noise equivalent absorption coefficient (NNEA) was 8.64 × 10-11 cm-1·W·Hz-1/2 [signal-to-noise ratio, (SNR) = 1] and according to the Allan variance analysis, a minimum detection limit of 500 ppb could be achieved for CO2 at 1204 s, which demonstrates the long-term stability of the system. The system was applied to detect the respiration of rice and upland rice seeds. It is demonstrated that the system can monitor and distinguish the respiration intensity and respiration rate of different seeds in real time.

Multi-wavelength fiber laser via evanescent field confinement with Al2O3 nanolaminate-coated thinned fiber

We present the fabrication and analysis of an Erbium-doped optical fiber laser emitting at multiple wavelengths. This is accomplished via a filter constructed from a fiber taper coated with alumina (Al2O3). The taper is created using the flame brushing induction technique with a combination of Butane (25 %) and Oxygen (75 %). The diameter is reduced to a 20 µm waist and 2 mm burner displacement. The thin film of Al2O3 was deposited via atomic layer deposition (ALD), resulting in a 15 nm layer. The coated fiber taper was then inserted into a ring fiber laser cavity functioning as a selector filter. This fiber laser produced an output comprising six simultaneous wavelengths: 1531.14, 1531.79, 1532.45, 1541.85, 1544.45, and 1562.22 nm. Laser signal stability tests were performed for one hour at 25 °C at the six emission wavelengths, resulting in a maximum optical power fluctuation of 0.15 to 0.33 dB, a wavelength shift variation of 0.02 nm, and a signal-to-noise ratio of 31.79 dB in average. The laser lines emitted have an average spectral width of 0.06 nm. Our results show that the typical performance of the fiber laser configuration based on an optical fiber taper was improved by the addition of the Al2O3 layer and can be further improved. Our findings demonstrate that the standard operation of the fiber laser setup, which utilizes an optical fiber taper, was enhanced through the incorporation of an Al2O3 layer and has the potential for further development.

Near-infrared sensitive differential Helmholtz-based hydrogen sulfide photoacoustic sensors.

A near-infrared (NIR) sub-ppm level photoacoustic sensor for hydrogen sulfide (H2S) using a differential Helmholtz resonator (DHR) as the photoacoustic cell (PAC) was presented. The core detection system was composed of a NIR diode laser with a center wavelength of 1578.13 nm, an Erbium-doped optical fiber amplifier (EDFA) with an output power of ∼120 mW, and a DHR. Finite element simulation software was used to analyze the influence of the DHR parameters on the resonant frequency and acoustic pressure distribution of the system. Through simulation and comparison, the volume of the DHR was 1/16 that of the conventional H-type PAC for a similar resonant frequency. The performance of the photoacoustic sensor was evaluated after optimizing the DHR structure and modulation frequency. The experimental results showed that the sensor had an excellent linear response to the gas concentration and the minimum detection limit (MDL) for H2S detection in differential mode can reach 460.8 ppb.

Explicit solutions from Darboux transformation for the two-component nonlocal Hirota and Maxwell–Bloch system

Based on the two-component Hirota and Maxwell–Bloch (H-MB) system, which describes the propagation of ultra-short pulses in erbium-doped nonlinear optical fibers, we derive two kinds of two-component nonlocal H-MB (NH-MB) systems by choosing suitable symmetries, namely [Formula: see text]-symmetric two-component NH-MB system and reverse space-time two-component NH-MB system. Then the explicit solutions of these two systems are obtained by the Darboux transformation.

Soliton Microcomb on Chip Integrated Si3N4 Microresonators with Power Amplification in Erbium-Doped Optical Mono-Core Fiber.

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we demonstrate a combined technique to access power-sufficient optical microcombs, with a photonic-integrated soliton microcomb and home-developed erbium-doped gain fiber. The soliton microcomb is generated in an integrated Si3N4 microresonator chip, which serves as a full-wave probing signal for power amplification. After the amplification, more than 40 comb modes, with 115-GHz spacing, reach the onset power level of >−10 dBm, which is readily available for parallel telecommunications , among other applications.

Optimisation of the efficiency of tapered erbium-doped optical fibre

We have developed a cladding pumped tapered erbium-doped fibre with a record-high core diameter for erbium-doped fibres (100 mm) and a near diffraction-limited beam quality (μ 2 ∼ 1.3). Optimisation of the tapered fibre parameters provided a high (18 %) efficiency of pump radiation conversion at a wavelength of 976 nm into signal radiation at a wavelength of 1560 nm.

Performance study of randomly coupled erbium-doped fiber amplifier using machine learning

This study describes the performance of a randomly coupled erbium-doped optical fiber amplifier (EOFA) using machine learning. A reinforcement learning-based artificial neural network (RL-ANN) is used to study various parameters of EOFA, such as gain, noise figure, and inter-core crosstalk for the 12-core EOFA. In addition to this, the relationship between mode-dependent loss, a penalty of the EOFA, and the average bending loss (BL) for three operating wavelengths, such as 1550, 1580, and 1600 nm, has been studied. To predict the performance of RL-ANN, three different machine learning algorithms, namely, K-nearest neighbor (KNN), ANN, and support vector machine (SVM) are used. The performance of the proposed RL-ANN is evaluated using five statistical error criteria: mean absolute error, root mean square error, scatter index, coefficient of variation, and overall index measurement. The statistical test result shows that the proposed RL-ANN provides the best performance compared to KNN, ANN, and SVM. The performance of the RL-ANN-based erbium-doped fiber amplifier (RA-EOFA) is studied and the results show that the gain and estimated NF based on a wavelength range from 1555 to 1565 nm provides a maximum gain. A comparison study was carried out for the proposed RA-EOFA with other learning methods. The results show that the proposed RA-EOFA provides the best performance in terms of less BL (0.25 dB), mode-dependent loss (0.5 dB), computational time (36.8 s), and a success rate of 98.39%.

Impact of coupling topology upon noise robustness of small optical reservoirs

In this work, we perform the numerical investigation of the performance of the small optical reservoir computing (RC) systems with four neurons using the commercial software for optical fiber communication system. The small optical RC system consists of the components of the optical fiber communication. The nonlinear function which is required in RC is provided by the erbium-doped optical fiber amplifiers (EDFA). We demonstrate that the EDFA should be operated in the saturated or non-linear regime to obtain a better performance of the small optical RC system. The performance of the small optical RC systems for different topological neuron structures is investigated. The results show that the interconnection between the neurons could offer a better performance than the systems without interconnection between the neurons. Moreover, the input signals with different noise levels are launched into the systems. The results show that the small optical RC system can classify the noisy input optical waveforms even when the signal-to-noise ratio is as low as − 2.55 dB.

Simulation solution for single and cascaded multi-wavelength Brillouin fiber lasers based on an analytical model

Abstract Here we propose a simulation model based on a previously reported analytical description of the Brillouin gain, that takes into account pump depletion, which allows us to make very accurate calculations for Brillouin fiber lasers (BFLs) working both in a single and cascaded multi-wavelength configurations. Output powers and conversion efficiencies are analyzed and compared with experimental results for various lasers setups using 25 km of a non-zero dispersion-shifted fiber (NZDSF) as the Brillouin gain media. In our experimental investigations, we used a pump laser at 1565 nm, with a bandwidth of 1 kHz, and output powers varying from 0 to its maximum value of 14 mW. We analyzed the laser behavior under various conditions using output couplers with output ratios varying from 10% to 90%, and to generate the cascaded Brillouin laser we have used a 10 m Erbium-doped optical fiber amplifier as a gain block in a separated cavity. Additionally, a spectral reconstruction is made based on power predictions of our model for the cascaded BFL with excellent agreement with experimental data.

Controllable excitations of rogue waves and breathers in an inhomogeneous erbium doped fiber system

We study the generalized nonlinear Schrödinger Maxwell–Bloch equation describing wave propagation in erbium-doped nonlinear fibers and derive the analytical bright and dark rogue wave and breather solutions under certain parametric conditions. We display the propagation properties of the attained solutions by modulating the relation between maximum effective propagation distance ζm and the parameter ζ0 relating to the excitation type of nonlinear waves. Their controllable behaviors such as fast appearance, postponement, sustainment and annihilation for exponentially dispersion decreasing fiber system have been demonstrated. Additionally, we delineate the longitudinal control of rogue waves. Our results may be useful in understanding and enriching the manipulation of rogue waves in resonant erbium-doped optical fibers.

Photosensitivity of composite erbium-doped phosphorosilicate optical fibres to 193-nm laser radiation

Results of studying photoinduced changes of a refractive index in the core of a composite erbium-doped phosphorosilicate optical fibre under pulsed UV irradiation at a wavelength of 193 nm and the annealing of these changes are presented and analysed. It is shown that the preliminary saturation of a composite optical fibre by molecular hydrogen substantially increases the photosensitivity. Analysis of thermal anneal kinetics revealed fundamental differences in the photosensitivity mechanisms between the optical fibres saturated with hydrogen and not subjected to hydrogen treatment. Initial and photoinduced absorption spectra of the phosphorosilicate glass are investigated. It is found that in the UV range, the induced absorption is mainly determined by a contribution from the intense absorption band of photoinduced phosphorus electron centres PO2 with a maximum at 4.7 eV (λ = 260 nm).

Suppression of stimulated Brillouin scattering in pulsed erbium-doped fiber amplifier through intensity-modulated counter pumping

We suppress stimulated Brillouin scattering in an erbium-doped optical fiber amplifier for 50-ns-long transform-limited signal pulses by counter-directional pumping with a pulse burst. The pump pulse burst is codirectional with the parasitic Brillouin Stokes wave, which, therefore, undergoes cross-phase modulation and thus spectral broadening due to the intensity-modulated pump. The broadening inhibits its growth. We experimentally study the effect of pump pulse parameters and improve the SBS threshold by up to 4 dB when amplifying signal pulses at a wavelength of 1565 nm with pumping at 1536 nm.

Simultaneous measurements of distributed temperature and discrete strain based on Hybrid Raman/FBG system

A hybrid optic fiber system is proposed and experimentally demonstrated, which combines the Raman-based distributed temperature sensing (DTS) and high-reflective fiber Bragg grating (FBG) sensors for discrete static strain measurement along the same sensing fiber. A distributed feedback laser (DFB) is adopted to generate stimulated emission (STE) light pulses for demodulation of optical time domain reflectometry (OTDR) technology, and an erbium-doped optical fiber amplifier (EDFA) is utilized to increase the power of laser and produce spontaneous emission (SPE) lights. Thus the STE light is employed as pump light for temperature demodulation through Raman-based DTS, as well the SPE lights can be used for discrete strain demodulation through wavelength division multiplexing of FBGs. Since the central wavelengths of FBGs are far away from the lasing wavelength of the laser, the FBG-induced insertion loss can be negligible, therefore the lights reflected by FBGs have little influence on the performance of DTS system. The strain information can be obtained through deducting the temperature induced wavelength shifts of FBGs, since the temperature information can be achieved by DTS system in advance. The experimental results show the maximum measurement error of temperature and strain are 0.48 °C and 10.47 με, respectively. This hybrid system indicates an effective improved multiplexing scheme based on the Raman-based DTS for simultaneous measurements of distributed temperature and discrete static strain, and a better solution of cross sensitivity problem in FBGs.

Erbium-doped optical fibre with enhanced radiation resistance for superluminescent fibre sources

This paper presents a study of the properties of erbium-doped optical fibres with enhanced gamma-ray resistance at a high dose rate. The fibres have a silica core containing different dopants. The gamma-ray resistance of the fibres is due to additional doping of their core with cerium and germanium ions, as well as to aluminium concentration optimisation. We assess the effect of fibre composition on the radiation-induced loss at a wavelength of 1310 nm and the output power and weighted average wavelength of superluminescent fibre sources based on erbium-doped fibre under pulsed gamma irradiation (dose per pulse, ∼ 20 Gy). The fibre doped with aluminium, germanium and cerium oxides is shown to be optimal for use in gamma-ray-resistant broadband superluminescent fibre sources.

Experimental Measurement of Erbium-Doped Optical Fibre Charecteristics for Edfa Performance Optimization

Abstract The paper presents experimental study of the major erbium-doped fibre amplifier (EDFA) features such as gain at low signal and gain saturation by an application of different erbium-doped optical fibres (EDFs). The main objective of the research is to estimate how the performance of EDFA varies depending on the length of doped fibre, pumping configuration scheme, as well as excitation source power. It is shown that a high gain coefficient of 16–20 dB can be practically achieved.

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.

151-km single-end phase-sensitive optical time-domain reflectometer assisted by optical repeater

A phase-sensitive optical time-domain reflectometry (ϕOTDR) system that can detect intrusion over 150 km is presented. The ϕOTDR system uses nonbalanced optical repeaters to extend the sensing distance. The repeater consists of two erbium-doped optical fiber amplifiers (EDFAs) and one Raman amplifier (RA). One EDFA power amplifier amplifies the forward-transmitting pulse, and one EDFA preamplifier is used for the backscattering signal, respectively. The RA helps keeping the power along the fiber stable. The optical repeater is installed at the connection of two adjacent fibers to compensate the power decline due to fiber loss. It is easy to install the repeater midway among the fiber links in the system for longer-distance sensing since there is no need of modifying the original sensing system. The theoretical analysis of the repeater is given to describe its effect on the distributed sensing. In experiments, several ϕOTDR traces show a good agreement with theoretical results. Using the optical repeater, 35-Hz vibration at 151 km is successfully measured with signal-to-noise ratio of 8 dB without extra signal processing.

Distributed feedback fiber laser based on a fiber Bragg grating inscribed using the femtosecond point-by-point technique

A distributed feedback (DFB) fiber laser based on a 32-mm long pi-phase-shifted fiber Bragg grating inscribed using the femtosecond point-by-point technique in a single-mode erbium-doped optical fiber (CorActive EDF-L 1500) is demonstrated. The lasing power of the DFB laser reaches 0.7 mW at a wavelength of 1550 nm when pumped with a laser diode at a wavelength of 976 nm and power of 525 mW. The width of the lasing spectrum is 17 kHz. It is shown that the pi-phase-shifted fiber Bragg grating fs-inscribed in a non-PM fiber provides the selection of the single polarization mode of the DFB laser. DFB laser formation in a highly doped non-photosensitive optical fiber (CoreActive SCF-ER60-8/125-12) is also demonstrated.

Dynamics of Peregrine combs and Peregrine walls in an inhomogeneous Hirota and Maxwell-Bloch system

Under investigation in this paper is an inhomogeneous Hirota-Maxwell-Bloch (IHMB) system which can describe the propagation of optical solitons in an erbium-doped optical fiber. The breather multiple births (BMBs) are derived with periodically varying group velocity dispersion (GVD) coefficients. Under large periodic modulations in the GVD coefficient of IHMB system, the Peregrine comb (PC) solution is produced, which can be viewed as the limiting case of the BMBs. When the amplitude of the modulation satisfies a special condition, the Peregrine wall (PW) that can be regarded as an intermediate state between rogue wave and PC is obtained. The effects of the third-order dispersion on the spatiotemporal characteristics of PCs and PWs are studied. Our results may be useful for the experimental control and manipulation of the formation of generalized Peregrine rogue waves in inhomogeneous erbium-doped optical fiber.

Analytic study on certain solitons in an erbium-doped optical fibre

()-dimensional non-linear optical waves through the coherently excited resonant medium doped with the erbium atoms can be described by a -dimensional non-linear Schrödinger equation coupled with the self-induced transparency equations. For such a system, via the Hirota method and symbolic computation, linear forms, one-, two- and N-soliton solutions are obtained. Asymptotic analysis is conducted and suggests that the interaction between the two solitons is elastic. Bright solitons are obtained for the fields E and P, while the dark ones for the field N, with E as the electric field, P as the polarization in the resonant medium induced by the electric field, and N as the population inversion profile of the dopant atoms. Head-on interaction between the bidirectional two solitons and overtaking interaction between the unidirectional two solitons are seen. Influence of the averaged natural frequency on the solitons are studied: (1) can affect the velocities of all the solitons; (2) Amplitudes of the solitons for the fields P and N increase with decreasing, and decrease with increasing; (3) With decreasing, for the fields P and N, one-peak one soliton turns into the two-peak one, as well as interaction type changes from the interaction between two one-peak ones to that between a one-peak one and a two-peak one; (4) For the field E, influence of on the solitons cannot be found. The results of this paper might be of potential applications in the design of optical communication systems which can produce the bright and dark solitons simultaneously.