Optical Fiber Amplifiers Research Articles

Nd3+-doped B2O3-SiO2-AlF3-NaF-CaF2 glass ceramics for 1.06 μm emission

Trivalent neodymium (Nd3+) doped transparent oxyfluoroborosilicate glass and glass ceramics (GCs) comprising CaF2 nanoparticles (NPs) were fabricated via melt quench route followed by two step heat treatment process. The X-ray diffraction and scanning electron microscopic studies confirm the presence of CaF2 NPs. The GC environment for efficient luminescence was obtained at a heat treatment of 450 °C/1 h. The wavelength of pumping laser source was optimized as 808 nm by studying the luminescence properties at different excitations. The Nd3+ ions exhibit their characteristic emission transitions with peak maxima at around 0.89 μm (4F3/2 → 4I9/2), 1.06 μm (4F3/2 → 4I11/2) and 1.32 μm (4F3/2 → 4I13/2). The Nd3+ concentration was also optimized as 1.0 mol% for strong emission up on 808 nm pumping. Various spectroscopic, radiative and laser characteristic parameters were determined using Judd-Ofelt theory. The luminescence decay of 4F3/2 state was studied controlling the excitation and emission wavelengths at 808 and 1060 nm, respectively. The reasons for quenching in luminescence were discussed with suitable illustrations. The experimentally observed results confirm that the GC sample obtained at 450 °C/1 h heat treatment was highly appropriate to design 1.06 μm fiber lasers and optical amplifiers.

Comparative study of spectroscopic properties of Er3+-ion doped K2O/KF-Gd2O3-P2O5 glass systems

The two phosphate glasses with composition 17K2O−17Gd2O3−65P2O5−01Er2O3 and 17KF−17Gd2O3−65P2O5−01Er2O3 composition were synthesized by conventional-melt quenching techniques to study comparatively the spectroscopic, Judd–Ofelt (JO), radiative properties and NIR-luminescent properties. The Urbach energy of K2O−Er and KF-Er samples was 0.3547 and 0.4799 eV. The observed trend is Ω2>Ω4>Ω6 and Ω2>Ω6>Ω4 for JO-intensity-parameters for K2O−Er and KF-Er glasses. Moreover, K2O−Er has higher Ω4 and Ω6 values, thus having more rigidity and viscosity than KF-Er. The measured values of full-width-half-maximum (FWHM) for K2O−Er and KF-Er glasses 54.60 and 58.27, respectively. The measured values of FWHM for K2O−Er and KF-Er glasses were 54.60 and 58.27, respectively. The A R values are 417.61 and 3038 for K2O−Er and KF-Er glasses, respectively. The radiative lifetime (τ R ) for K2O−Er and KF-Er glasses is 2.39 ms and 3.18 ms, respectively. Utilizing McCumber theory the G(λ,β) is positive and population-inversion is more than 0.4 for both glasses. Both samples have flat gain-bandwidth in the range of 1505–1585 nm, which covers the S-, C-, and L-bands of the low-loss optical communication-window. It is evident from all these results that the prepared glass samples have the potential for a low-threshold and high gain NIR laser and optical-fiber amplifier.

Metal Nanowire‐Induced Enhancement of Surface Emission in Luminescent Glass

AbstractLuminescent glass, as an important component of photonic materials, is extensively utilized in applications such as lasers and optical fiber amplifiers, which demand high quantum efficiency. To further enhance the surface emission performance of luminescent glass, this study introduces a novel approach by employing custom‐made metal nanowires, applying them as coatings on the surface of Erbium‐doped glass, rather than embedding traditional metal nanoparticles. Utilizing experimental techniques and Finite‐Difference Time‐Domain (FDTD) simulations, it is demonstrated that the surface‐emission from Erbium‐doped glass coated with silver nanowires or copper nanowire‐graphene hybrids is significantly increased, showing an enhancement rate of up to 117.27% compared to intrinsic glass. Extended FDTD analysis reveals that variations in the size and density of the nanowires can optimize emission characteristics, thereby improving the emission performance of luminescent glass. The enhancement of the local electromagnetic field at the interface underscores the efficacy of metal nanowires in boosting photonic materials. This study not only highlights the practicality of metal nanowires in photonics but also introduces a rapid deployment pathway for customizing photonic interactions through nano‐engineering, potentially extendable to other photonic materials.

Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics for fiber laser applications

Transparent Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics (BSEr1TmxGCs) with variable Tm3+ concentration were prepared through melt quench process followed by reheat treatment at 450 °C/1h. They were characterized through differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) Raman spectroscopy, near infrared (NIR) emission and luminescence decay. The formation of CaF2 nanocrystallites against oxyfluoroborosilicate glassy phase was confirmed by scanning electron microscopic (SEM) and hi-resolution transmission electron microscopic (HRTEM) studies. The NIR emission properties were investigated at 460 nm diode laser pumping. The applicability of BSEr1TmxGCs were examined by evaluating effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe × Δλeff), figure of merit (σe × τR) and quantum efficiency (ηQE). The energy transfer efficiency (ηET), rate of energy transfer (WET) between Er3+ and Tm3+ and the rate of non-radiative transitions (WNR) were also calculated. The comparative NIR emission performance suggests that the BSEr1Tm1GC has proficiency for 1530 nm broadband fiber lasers and optical amplifiers in short wavelength and conventional wavelength (S + C) band communication window.

Er3+ -doped oxyfluoroborosilicate glass ceramics with embedded CaF2 nanoparticles for 1.53 μm broad band applications

The CaF2 based oxyfluoroborosilicate glasses and glass ceramics doped with Er3+ ions were prepared via melt quench process followed by heat treatment and characterized for 1.53 μm broadband applications. The optimized glass ceramic sample was obtained at 450oC/1h heat treatment. The Er3+ concentration was optimized as 1.0 mol% for efficient emission at 460 nm excitation through concentration dependent luminescence analysis. The spectroscopic parameters such as Ωλ=2,4,6 parameters and the radiative parameters such as spontaneous transition probability rates (AR), branching ratios (βR) and decay times (τR) were calculated applying the standard Judd-Ofelt theory. The effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe×Δλeff), quantum efficiency (η) and figure of merit (σe×τR) were calculated as 25.78 nm, 13.42×10-21 cm2, 3.46×10-26 cm3, 82.83% and 5.32×10-23 cm2s, respectively for the optimized glass ceramic sample. The exchange type of energy transfer among the excited Er3+ ions results the quenching in luminescence and the non-exponentiality in decay curves. The systematic investigations carried out indicate that the glass ceramic obtained at 450oC/1h heat treatment was proficient for 1.53 μm broadband fiber lasers and optical amplifiers in S and C band communication window.

Spectroscopic, vibrational and structural insights into LaYbO3:Pr3+ and LaLuO3:Pr3+,Tb3+ perovskites at ambient and high-pressure conditions

The interlanthanide perovskites LaYbO3:Pr3+ and LaLuO3:Pr3+,Tb3+ were synthesized by a solid-state reaction and characterized at ambient conditions by means of X-ray diffraction (XRD), Raman spectroscopy and photoluminescence techniques. XRD measurements have shown that the synthesis method provided samples with pure perovskite phase (space group Pnma) for LaYbO3, while in the case of the LaLuO3 compound small traces of Lu2O3 could be found after several annealing. Up to 13 Raman active modes were observed in the Raman spectra of the studied perovskites and theoretical calculations performed for LaYbO3 allowed to assign their symmetry. Regarding their optical properties, the emission from Tb3+ ions at B sites of the ABO3 perovskite could be distinguished. Moreover, NIR emission from Pr3+ was observed in the LaLuO3 perovskite at ∼1000 nm and 1250–1600 nm. Emission in these spectral regions could be relevant for Si-based solar cell applications and fiber optic amplifiers, respectively. Moreover, the stability of both perovskites under high-pressure conditions has been studied spectroscopically, finding that LaYbO3 is stable up to 19 GPa and that LaLuO3 undergoes a possible pressure-induced phase transition at ∼21–24 GPa. This makes LaLuO3 the first interlanthanide perovskite showing phase transition under 40 GPa.

Broad emission in Bi-doped GeGaSe chalcogenide glass and glass-ceramic

Bi-doped Ge23.5Ga11.8Se64.7 glasses were prepared, and compositional dependence of broadband near-infrared photoluminescence at 1.26 μm was investigated. The maximum intensity of the emission appeared at 0.3 mol% Bi doped glasses. The glass was further annealed to create glass-ceramics, and their photoluminescence intensity was found to decrease as the heat treatment time increases. The broadband infrared photoluminescence of Bi ions in the glasses is mainly due to the low valence state of Bi, and broad emission from a half-width at full maximum up to 550 nm demonstrates potential applications of the glasses and glass-ceramics in new broadband fiber lasers and optical amplifiers.

Detailed scrutiny of FWM in holmium-doped fiber amplifier (HOFA) in WDM systems

Abstract Four wave mixing (FWM) in wavelength division multiplexed (WDM) systems is prominent performance degrading nonlinearity and limits the total capacity of the system. FWM is explored in different fiber optical amplifiers such as erbium-doped fiber amplifier (EDFA), Raman fiber amplifier (RFA), and also in semiconductor optical amplifier (SOA). Reported studies in HOFA revealed that nonlinear effects in these amplifiers are low; however, in present study, in this research article WDM-HOFA system has been simulated and studied FWM in detail at different HOFA parameters such as input power, length, core radius, doping radius, numerical aperture (NA), Ho ion density, and effects of co- and counter-pumping. Gain and noise figure (NF) are also investigated at aforementioned parameters, and performance is evaluated in terms of optical signal to noise ratio (OSNR) at 2,030 nm wavelength window. It is observed that least FWM obtained at 3 m Ho fiber length, 2 µm core radius and doping radius, 15.6 × 1023 m−3 Ho ion doping, 0.1 NA, −10 dB input power, 0.8 GHz channel spacing, and 4 WDM channels. However, better gain and NF comes at different values of these parameters, and as a result, there is trade-off between FWM and gain, NF.

Bismuth-Doped Fiber Lasers and Amplifiers Operating from O- to U-Band: Current State of the Art and Outlook

The development of unique optical materials that provide amplification and lasing in new wavelength ranges is a major scientific problem, the solution of which is becoming the basis for the emergence of new optical technologies, which are primarily targeting the expanding of operating wavelengths in silica glass. In fact, one of the notable advances in the field of fiber optics over the past two decades has been the production of a new type of laser-active fibers (namely bismuth-doped fibers), which has made it possible to cover previously inaccessible (for rare-earth-doped fibers) spectral ranges, in particular O-, E-, S-, and U-telecom bands. The advance in this direction has led to further growth of the technological capabilities in the telecom industry for amplification and generation of optical radiation in various wavelength bands, which will result in the near future to overcoming the problem known as “capacity crunch” by means of expanding the data transmission range. Recently, bismuth-doped fibers have been actively studying in order to improve their characteristics, which would allow for efficient implementation of optical devices based on bismuth-doped fibers (BDFs) with deployed telecommunications systems. This is one of the dynamically developing areas, where progress has already manifested in form of emergence of new achievements, in particular commercially available various types of BDFs, as well as a series of novel fiber-optic amplifiers for the O- and E-bands. In this review, a number of scientific studies that have already led to a noticeable progress in the field of optical properties of BDFs and the practical implementation of optical devices (lasers and amplifiers) based on them are presented and discussed, with much attention to the achievements of recent years.

Nd3+-doped Fiber Laser at 1000-1100nm

Fiber optic amplifiers have revolutionized telecommunications by enabling efficient signal amplification over long distances. Their development stems from the increasing demand for high-speed data transmission and the limitations of traditional electronic amplifiers. Fiber amplifiers utilize rare-earth-doped fibers to boost optical signals, offering advantages in bandwidth, reliability, and cost-effectiveness. Nd3+-doped fiber laser is one of the focal topics of current research. Researchers have found advancements in the application of Nd3+-doped fiber laser at wide wavelengths. However, there still exist uncertainties in applying Nd3+-doped fiber laser at 1000-1100nm. Therefore, this paper aims to design a Nd3+-doped fiber laser at 1000-1100nm. The research methodology of this paper is as follows: using numerical simulation via Matlab. Research finds that Nd3+-doped fiber laser at 1000-1100nm is theoretically applicable. The results of this research will promote the development of optical fiber. Through an in-depth exploration of new materials and application technologies, it will bring breakthroughs in optical fiber communication, optical sensing, laser technology, and other fields. This will promote the improvement of laser performance and provide a more reliable and efficient basis for future scientific research and engineering applications.

Design, optimization, and analysis of thulium-doped optical fiber amplifiers for E-band communication

Design, optimization, and analysis of thulium-doped optical fiber amplifiers for E-band communication

Polymer optical fiber amplifier based on all-inorganic perovskite quantum dots

The proliferation of polymer optical fibers (POFs) has opened multiple avenues of optical-based networks and sensing applications in the visible spectral range. However, the lack of efficient amplifiers significantly hinders their utilization in practical scenarios. As emerging gain media, halide perovskites have attracted considerable attention in exploring their practical applications. In this Letter, we investigated the optical gain properties of cesium lead bromide quantum dots (CsPbBr3 QDs), and by facet dip-coating, we realized a polymer optical fiber amplifier. Under a 400-nm, 163-fs Ti:Sapphire laser pumping, the amplified spontaneous emission (ASE) thresholds of 1.6 and 20.1 μJ/cm2 were achieved through stripe pumping of a QDs-thin-film and end-pumping of a polymer-fiber facet dip-coated with the QDs, respectively. A gain coefficient of 232.2 ± 22.8 cm−1 was obtained using the variable stripe length method. By coupling a broadband continuous-wave light source into the POF as the signal, the optical gain behavior was studied with varying pump fluence and signal power density. More than 20 dB optical gain was achieved within the ASE wavelength region of 530–540 nm with a predicted theoretical maximum gain of 33.6 dB. The research verifies the feasibility of amplifying continuous-wave signals in the visible spectrum and potentially closing the research gap in visible-light optical-to-optical amplifiers. This opens the avenue for further research and innovations in practical polymer-based optical amplification for a plethora of applications, including all optical processing chips and short-range interconnects, as well as visible-light and underwater communications.

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.

Noise-like pulse generation by amplified well-defined pulse in an optical fiber with negative group velocity dispersion

We experimentally and numerically demonstrate that noise-like pulses (NLPs) can be generated by pumping well-defined pulses (WDPs) into an optical fiber amplifier at a wavelength in the region of negative group velocity dispersion. Through investigating the evolution of the optical pulses, it is realized that the output pulses consist of NLPs at the pump wavelength and split solitons at Stokes wavelengths, due to intrapulse Raman scattering followed by the process of soliton fission. Such process of pulse breakup results in the generation of sub-pulses that have peak powers much higher than the unbroken WDPs have, enabling WDPs to strongly induce nonlinear effects. This finding resolves the discrepancy between the experiment and simulation results of supercontinuum generation by using picosecond WDPs in previous research.

Temperature eigenfunction basis for accelerated transverse mode instability simulation.

This work presents a model for the simulation of transverse mode instability (TMI) in rare earth doped optical fiber amplifiers. The model evaluates the internal temperature of a fiber using a superposition of a finite number of thermal eigenmodes. This simplification greatly enhances the speed of calculation with negligible impact on calculation accuracy. This new method is described and quantitatively compared to an older model that uses standard, spatially resolved FDTD to integrate the heat diffusion equation. When tested over a range of spatial and temporal resolutions, this model reduces runtime by a factor of ∼13.9 on average relative to identical simulations using the spatially resolved model.

Comparative study of single pump all optical fiber amplifiers (POAs) with ultra wide band and high gain fiber optic parametric amplifiers in highly nonlinear fibers

Abstract This paper has clarified comparative study of single pump all optical fiber amplifiers with ultrawide band and high gain fiber optic parametric amplifiers in highly nonlinear fibers. Different amplifiers gain is demonstrated versus system distance for different light amplifiers in highly nonlinear fiber channel. As well as amplifier gain is clarified against system distance for different light amplifiers in DCF, DSF and NZDSF fiber channel. The mechanism of generation of single idler signal is studied based on single signal and pump signal. Moreover the mechanism of generation of single idler signal is analyzed and investigated clearly based on signal and two pump signals. Amplifier bandwidth is demonstrated against system distance for different fiber channel types in the presence of POA amplifiers based on 100 mW, 300 mW and 500 mW pumping power. The map of the signal losses is discussed and clarified versus wavelength band in the presence of all amplification techniques. Light signal per noise ratio and bit error rates are demonstrated against system distance for different fiber channel types in the presence of POA amplifiers based on 100 mW, 300 mW and 500 mW pumping power. POA is more suitable for the operation in HNLF fiber channel in compared to other proposed fiber communication channels. All optical amplifiers operation performance gain efficiency is compared together in different fiber channel media. The system can be employed with POAs for the fiber reach up to 100 km distance with a suitable amplifier gain and bandwidth. An important criteria for any amplifier is its gain and bandwidth for the compensation of the system loss and dispersion together. The optimum suitable pumping power is clarified for upgrade the system amplifier performance signature.

10 W super-wideband ultra-low-intensity-noise single-frequency fiber laser at 1 µm.

A 10 W super-wideband ultra-low-intensity-noise single-frequency fiber laser (SFFL) at 1 µm is experimentally demonstrated, based on dual gain saturation effects from semiconductors and optical fibers, together with an analog-digital hybrid optoelectronic feedback loop. Three intensity-noise-inhibited units synergistically work, which actualizes a connection of effective bandwidth and enhancement of noise-suppressing amplitude. With the cascade action of the semiconductor optical amplifier and optical fiber amplifier, the laser power is remarkably boosted. Eventually, an SFFL with an output power of 10.8 W and a relative intensity noise (RIN) below -150 dB/Hz at the frequency range over 1 Hz is realized. More meaningfully, within the total frequency range of 10 Hz to 10 GHz exceeding 29 octaves, the RIN is controlled to below -160 dB/Hz, approaching the shot-noise limit (SNL) level. To the best of our knowledge, this is the lowest RIN result of SFFL within such an extensive frequency range, and this is the highest output power of the near-SNL super-wideband SFFL. Furthermore, a linewidth of less than 0.8 kHz, a long-term stable polarization extinction ratio of 20 dB, and an optical signal-to-noise ratio of over 60 dB are obtained simultaneously. This start-of-the-art SFFL has provided a systematic solution for high-power and low-noise light sources, which is competitive for sophisticated applications, such as free-space laser communication, space-based gravitational wave detection, and super-long-distance space coherent velocity measurement and ranging.

All-Optical format conversion from PAM4 to QPSK based on non-degenerate Phase-Sensitive amplification and pump assisted nonlinear optical loop mirror

An all-optical format conversion (AOFC) scheme from 4-ary pulse amplitude modulation (PAM4) to quadrature phase shift keying (QPSK) based on the non-degenerate phase-sensitive amplification (PSA) and the pump assisted nonlinear optical loop mirror (PA-NOLM) is proposed and numerically simulated for the first time. The input unipolar PAM4 signal with equal amplitude distance (UPAM4-A) is coupled with two input pump lights and injected into the symmetric interferometric fiber optic parameter amplifier (FOPA) to achieve the separation of the UPAM4-A and the new pump light generated at the signal frequency based on the non-degenerate PSA. When the filtered out UPAM4-A is coherent added with the new generated pump, the UPAM4-A signal to the biplolar PAM4 (BPAM4) signal. When the converted BPAM4 is sent into the PA-NOLM after adjusting its power, the BPAM4 signal could be converted into the QPSK signal. The error vector magnitude (EVM) and bit error ratio (BER) performance of the system are measured before and after AOFC with different input and receiver optical signal to noise ratio (OSNR). For the input UPAM4-A signal with an input OSNR of 27 dB, there is about 8.2 dB BER performance improvement in receiver OSNR for the final converted QPSK signal. Additionally, the proposed non-degenerate PSA configuration can be extended to realize the AOFC from one QPSK to two on–off keying (OOK) signals. The scheme can be applied in the optical gateway connecting the long-haul and the short-reach optical networks with suitable modulation formats.

A novel multicore Er/Yb co-doped microstructured optical fiber amplifier with peanut-shaped air holes cladding

Abstract The multicore fiber amplifier, as a key component in spatial division multiplexing (SDM) communication systems, presents higher technical difficulty compared to traditional multi-channel single core fiber amplifiers, which has sparked widespread attention. To achieve balance, efficiency, miniaturization, and cost-effectiveness in the performance of multi-core optical fiber amplifiers, we propose an innovative triple cladding 13-core Er/Yb co-doped microstructured fiber (13CEYDMOF). The proposed fiber features an outer cladding with peanut-shaped air holes, which enables uniform excitation of the 13 cores using a single multimode laser pump source within the inner cladding. This approach also prevents damage or aging of the fiber’s outer coating due to the pump laser. Furthermore, the design of Peanut-Shaped Air Holes effectively increases the numerical aperture (NA) of the inner cladding while reducing the outer diameter of the fiber, enhancing the fiber’s mechanical flexibility. To address the coupling difficulties caused by air holes, we bi-directionally pump the 13CEYDMOFA by utilizing a combined technique of the side winding and end pumping. The experimental results show that the 13CEYDMOFA can achieve an average gain of 23.8 dB, a noise figure (NF) of ∼4.6 dB, and an inter-core gain difference of less than 2 dB in the wavelength range of 1529–1565 nm. The in-line amplified transmission experiment demonstrates that the 13CEYDMOFA is well suited for the 13 spatial channels transmission. To the best of our knowledge, this is the first time to realize high performance telecommunication band amplification in a multicore microstructure fiber.

Short review and prospective: chalcogenide glass mid-infrared fibre lasers

Rare-earth ion doped, silica glass, optical fibre amplifiers have transformed the world by enabling high speed communications and the Internet. Fibre lasers, based on rare-earth ion doped silica glass optical fibres, achieve high optical powers and are exploited in machining, sensing and medical surgery. However, the chemical structure of silica glass fibres limits the wavelength of laser operation to < 2.5 µm, which excludes the mid-infrared longer wavelength range of 3–50 µm. Rare-earth ion doping of fluoride glasses enables manufacture of fibre lasers up to a limiting 3.92 µm wavelength, but the fluoride glass chemical structure again prevents operation at longer wavelengths. Optical fibre lasers that are constructed from different rare-earth ion doped chalcogenide glass fibres will potentially operate across the 4–10 µm wavelength range, where suitable high-power lasers currently do not exist. We present a short review here of our recent work in achieving first time, continuous wave, mid-infrared fibre lasing beyond 5 μm wavelength in Ce3+-doped selenide chalcogenide fibre. We place this disruptive breakthrough into the wider fibre laser context, and also present the unprecedented advances in new cross-sector applications that will be enabled by mid-infrared fibre lasers in the 4–10 µm wavelength range. To surpass the few mW power output of the Ce3+-doped chalcogenide glass fibre lasing achieved to date, the glass quality of the doped chalcogenide fibres must now be improved, similar to the challenges originally facing the first glass fibre lasers based on silica.