Ytterbium-doped Fiber Amplifier Research Articles

20 Watt single-frequency 509 nm laser by single-pass second harmonic generation in an LBO crystal

High power 509 nm continuous-wave (CW) lasers have important applications in science and communication. Here we demonstrate a robust high-power single-frequency 509 nm laser system based on nonlinear phase demodulation technique and single-pass second harmonic generation (SHG) configuration. In experiments, the single-frequency fundamental wave at 1018 nm was linewidth-broadened by an electro-optical modulator and then amplified to 207 W in a ytterbium-doped fiber amplifier. In subsequent single-pass SHG stage, over 20 W CW single-frequency 509 nm laser was generated in a LiB3O5 crystal with a SHG efficiency of 9.7%. To the best of our knowledge, this is the highest reported power for CW single-frequency 509 nm laser, which could be used for advanced underwater optical communication and preparation of cesium Rydberg state.

Four bits data sequence generators based ytterbium doped fiber amplifiers for upgrading maximum Q factor and minimum BER

Abstract We have simulated four bits data sequence generators based ytterbium-doped fiber amplifiers for upgrading max. Q factor and min. BER. Optical power variations against time duration after fiber cable length of 250 km with the bits sequence generators of 0101, 1000, and 1010 respectively are simulated. As well as the electrical power/total received power variations against frequency after photodetector receiver with the bits sequence generators of 0101, 1000, and 1010 respectively are discussed in details. Moreover, the signal power amplitude level with the time period duration after photodetector receiver/3R regenerator with the bits sequence generators of 0101, 1000, and 1010 respectively are clarified to show the max. Q factor and min. BER values for each case.

All-fiber laser system for all-optical 87Rb Bose Einstein condensate to space application.

In the development of the Cold Atom Physics Research Rack (CAPR) on board the Chinese Space Station, the laser system plays a critical role in preparing the all-optical 87 R b Bose-Einstein condensates (BECs). An all-fiber laser system has been developed for CAPR to provide the required optical fields for atom interaction and to maintain the beam pointing in long-term operation. The laser system integrates a 780nm fiber laser system and an all-fiber optical control module for sub-Doppler cooling, as well as an all-fiber 1064nm laser system for evaporative cooling. The high-power, single-frequency 780nm lasers are achieved through rare-Earth doped fiber amplification, fiber frequency-doubling, and frequency stabilization technology. The all-fiber optical control module divides the output of the 780nm laser system into 15 channels and regulates them for cooling, trapping, and probing atoms. Moreover, the power consistency of each pair of cooling beams is ensured by three power tracking modules, which is a prerequisite for maintaining stable MOT and molasses. A high-power, compact, controlled-flexible, and highly stable l064nm all-fiber laser system employing two-stage ytterbium-doped fiber amplifier (YDFA) technology has been designed for evaporative cooling in the optical dipole trap (ODT). Finally, an all-optical 87 R b BEC is realized with this all-fiber laser system, which provides an alternative solution for trapping and manipulating ultra-cold atoms in challenging environmental conditions.

Investigation of MDRZ and DPSK modulation schemes employed in DWDM systems for smart city 5G access networks

Wavelength division multiplexing (WDM) is one of the emerging technologies for data transmission in 5G access network assembly between the antenna unit (AU) and the distribution unit (DU). Here, in this work, we evaluate and analyze a dense wavelength division multiplexing (DWDM) — passive optical networks (PONs) employing erbium–ytterbium-doped fiber amplifier (EYDFA) [Formula: see text] Raman hybrid optical amplifier (HOA) using two modulation schemes — modified duobinary return to zero (MDRZ) and differential phase shift keying (DPSK) for alternate channels, where the channel count has been varied from 8 to 40. The system has been analyzed over the wavelength span of 1550–1558.8[Formula: see text]nm with a channel spacing, input power and data rate of 25[Formula: see text]GHz, 0[Formula: see text]dB and 40[Formula: see text]Gb/s, respectively. An average gain, gain ripple and optical signal-to-noise ratio (OSNR) of 20.87, 0.95 and 30[Formula: see text]dB, respectively have been observed in the case of HOA along with the achievement of [Formula: see text]-factor of up to 9 at the receiving end of the system. The DPSK-modulated channels result in higher values of gain and OSNR along with lower gain ripple as compared to MDRZ channels making the proposed system a good option for 5G access network applications.

Optimal Design of Fiber Amplifier based on Thulium, YttErbium and Bismuth.

Although Erbium-doped fiber amplifier is still the mainstream of optical fiber communication nowadays, it has some limitations. The operation of EDFA is limited to 1530-1610nm, so it is an important research direction to explore different elements. This paper introduces three kinds of fiber amplifiers doped with different rare earth elements: Thulium-doped, YttErbium-doped, and Bismuth-doped fiber amplifiers. The optimal optimization performance is obtained through comparison logic by adjusting various parameters. The maximum gains of three rare-earth-doped fiber amplifiers in different wavelength ranges are obtained: The maximum gain of a Thulium-doped fiber amplifier is 51dB in the wavelength range of 1900nm to 2050nm. The maximum gain of a YttErbium-doped fiber amplifier is 62. 5dB in the wavelength range of 1020nm to 1080nm. The maximum gain of a Bismuth-doped fiber amplifier is 23dB in the wavelength range of 1640nm to 1770nm. These works pave the way for future research.

Theoretical Analysis of Thermal Distribution and Waveform Evolution in Pulsed Ytterbium-Doped Fiber Amplifier with Extra Feedback

Pulsed ytterbium-doped fiber amplifiers (YDFA) with ns-level signal width are important devices for obtaining high-power pulsed lasers. When some components in the amplifier are ineffective, e.g., the isolator or fiber is damaged, extra feedback light is generated and coupled into the gain fiber. The dynamic thermal distribution and waveform evolution of amplifiers with extra continuous-wave (CW) or pulse-wave (PW) feedback are theoretically analyzed in this work. The CW feedback can not only reduce the gain of the amplifier but can also change the thermal distribution of the gain fiber, while the PW feedback can reduce the leading or trailing edge of the output pulse by 3–4 ns, depending on the direction of the feedback light transmission. The theoretical analysis provides a reference for optimizing the thermal management and the fault diagnosis of a typical fiber amplifier with an output of several tens of watts.

Exploiting the two-dimensional magneto-optical trapping of Hg199 for a mercury optical lattice clock

Two-dimensional magneto-optical trapping (2D-MOT) is an efficient tool for generating a high flux of precooled atoms. A 2D-MOT for mercury (Hg) is so far missing despite the potential of this atomic species in several areas. Here, we present the characterization of a 2D-MOT for Hg enabled by addressing the ${}^{1}{S}_{0}$- ${}^{3}{P}_{1}$ laser cooling transition at 254 nm. The laser source based on an ytterbium-doped fiber amplifier has low-frequency noise and high reliability. Parameters affecting the efficiency of the 2D-MOT are studied, i.e., optical trapping power, push beam power, cooling laser frequency detuning, and magnetic-field gradient. When used with a Hg optical lattice clock, the 2D-MOT increases by a factor of 4.5, the rate of preparation of the atomic samples, yielding an improved clock short term stability of $6.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ at 1 s.

714 W all-fiber supercontinuum generation from an ytterbium-doped fiber amplifier

An all-fiber supercontinuum (SC) source with record average output power of 714 W and spectrum ranging from 690 nm to 2350 nm is demonstrated. The method of SC generation from an ytterbium-doped fiber amplifier is used to achieve the high-power SC output. The source also exhibits a flat spectrum ranging from 1050 nm to 2095 nm at the −10 dB level. The parameters that influence the output power and spectrum of SC, including the pulse width of the seed laser and the passive fiber length in the last stage fiber amplifier, are analyzed in detail. To the best of our knowledge, the output power of SC in this work is the highest power that has been publicly reported. The scheme has the advantage of good robustness, which also has the potential to further increase the SC output power to the kilowatt level.

Study of the reabsorption effect on the ytterbium-doped fiber amplifiers

In this paper, the rate equation of ytterbium (Yb) ion concentration in the upper level and the transmission equations of seed signal, pump, and amplified spontaneous emission (ASE) in the Yb-doped fiber amplifier are solved simultaneously by the explicit Runge–Kutta method. Finally, a full seed signal power spectrum simulation with the range of 1000–1130 nm is achieved. This paper focuses on the amplification of seed signals at different peak wavelengths in different Yb-doped fiber lengths. The main works are as follows: By constructing a 3D data structure of the seed signal, a parallel computing work on the propagation process of Gaussian-lineshape seed spectrum with a peak wavelength of 1000–1100 nm in Yb-doped fiber with a length of 1–30 m has been done, which significantly reduces the calculation time. Furthermore, the accuracy of calculation results has been improved by the iterative method. Finally, the reabsorption effect on the seed signals at different peak wavelengths and the competition between the seed signal and ASE have been analyzed in both single-mode and large-mode-area fibers, and the optimal gain fiber length corresponding to the different peak wavelengths of the seed signal has also been discussed.

Controlled generation of picosecond-pulsed higher-order Poincaré sphere beams from an ytterbium-doped multicore fiber amplifier

Higher-order Poincaré sphere (HOPS) beams with spatially variable polarization and phase distributions are opening up a host of unique applications in areas ranging from optical communication to microscopy. However, the flexible generation of these beams with high peak power from compact laser systems remains a challenge. Here, we demonstrate the controlled generation of HOPS beams based on coherent beam combination from an Yb-doped multicore fiber (MCF) amplifier. Using a spatial light modulator to adaptively adjust the wavefront and polarization of the signals seeded into the individual cores of the MCF various structured beams (including cylindrical vector beams and first- and second-order vortex beams) were generated with peak powers up to 14 kW for ∼ 92 ps pulses.

Review of High Average Power and High Beam Quality LD-Pumped Ytterbium-Doped Fiber Laser Oscillators and Amplifiers

Review of High Average Power and High Beam Quality LD-Pumped Ytterbium-Doped Fiber Laser Oscillators and Amplifiers

FTTH 방송 오버레이용 EYDFA 부품과 핵심 시스템 개발 및 연구

In this study, erbium ytterbium doped fiber amplifier components and core systems for fiber to the home broadcast overlays are developed and evaluated to ensure stable high-power light even during long-distance data transmission in broadcast networks. Consequently , data transmission in the broadcasting network is found to be low in loss, long-distance transmission is deemed possible, and stable optical signals can be amplified using domestic equipment instead of expensive foreign equipment. The tools developed in this study provide an opportunity to reduce dependence on overseas products by allowing domestic technology, which lacks optical amplifier technology, to compete with overseas products at a low price. In the future, these tools are expected to accommodate more members from the optical communication field and be applied to various fields that use high-power light.

The Gain performance of Ytterbium Doped Fiber Amplifier

Ytterbium doping provides high capacity for producing large gain per unit length, and versatility in pump optimization for a given gain length .The paper presents gain characteristic of Ytterbium doped Fiber Amplifier in terms of amplifier length, Yb ion density, pump power and signal power at pump wavelength λp =910 nm and signal wave length λs =975 nm s. A maximum gain of (39, 37 and 33dB) obtained for pump powers (150, 100 and 50 mw). The gain occurs over short length (tenth of centimeters) of the amplifier and increase with increasing Yb ion density. It begins to be moderately saturated when ion concentration exceeds 1.3 e+025. After certain pump power gain values become saturated while it decreases rapidly by increasing signal power. As a result of laboratories unavailability in the region the layout done by using Optisystem 8.0 software simulation (Optical Amplifier and Communication System Design Software)

On the initiation of fiber fuse damage in high-power ytterbium-doped fiber lasers

Fiber fuse effect can occur spontaneously and propagate along optical fibers to cause widespread damage; it threatens all applications involving optical fibers. This paper presents two results. First, it establishes that the initiation of fiber fuse (IFF) in silica fibers is caused by virtual-defect-induced absorption. Critical temperatures and critical optical powers for IFF are simulated for the first time using a 3D solid-state heat transfer model with heat source generated by the virtual-defect-induced absorption. In this method, formation energies of the virtual defects can be uniquely determined, which offers critical information on the chemical reasons for fiber fuse. Second, this paper offers a method to evaluate operating temperatures of fiber lasers. General analytical solutions of the operating temperatures along gain fibers are deduced. Results of 976-nm laser-diode-pumped and 1018-nm tandem-pumped ytterbium-doped fiber (YDF) amplifiers using 10/130-μm YDFs are calculated. Potential limits caused by fiber fuse are discussed.

Effect of the seed power spectral density on spectral broadening in kW-level narrow-linewidth fiber amplifiers

Narrow-linewidth high-power fiber amplifiers are demanded in the spectral beam combining technique for power scaling. This article has experimentally studied the seed power spectral density (PSD) effect on the spectral broadening in all-fiber high-power narrow-linewidth fiber amplifier based on fiber Bragg grating (FBG) structure. It was found that the spectral bandwidth of the amplifier output reduces by increasing the PSD of the seed source. During the experiments, a ytterbium-doped fiber (YDF) amplifier was injected by three seed sources with the PSDs of 1.27 W/pm, 1.5 W/pm and 1.8 W/pm to scale up the seed power. After amplification, the resultant 3-dB spectral bandwidth of the amplifier was measured to be 88 pm, 61 pm, and 41 pm, respectively, at kW-level power. Meanwhile, we developed a 990 W fiber amplifier with a 3-dB spectral bandwidth of 41 pm; the narrowest spectrum achieved using a simple FBG-based master oscillator power amplifier configuration at this power level.

Performance Enhancement of Ytterbium-Doped Fiber Amplifier Employing a Dual-Stage In-Band Asymmetrical Pumping

The performance of doped fiber amplifiers can be enhanced significantly with the help of multi-stage pumping technique provided that various critical parameters of pumps including their optical power and wavelength are optimized. We report the performance enhancement of a ytterbium doped fiber amplifier (YDFA) for a 1.02–1.08 m spectral region with an optimized design based on a novel dual-stage in-band asymmetrical pumping scheme. By accurately adjusting the optical power and wavelength of pumps in both the stages, a record peak gain of around 62.5 dB and output power of 4.5 W are achieved for a signal wavelength of 1.0329 m at an optimized length of Ytterbium-doped silica fiber and optimized doping concentration of Yb. Moreover, a minimum noise figure (NF) of 4 dB is observed for a signal wavelength of 1.0329 m at the optimized parameters. Similarly, the effect of using high and low pump powers at the first and the second stage, respectively, on NF of the amplifier is also investigated at different values of signal powers. It is observed that the value of NF increases significantly by using high pump power at the first stage and low pump power at the second stage.

Thermal management in high‐power Erbium Ytterbium doped fiber amplifiers for optimum efficiency

Cladding pumping is considered to be one of the best amplification approaches in view of the capital and operational expenditure for the development of high-power optical amplifiers. Such schemes use multimode high-power pump lasers as the pumping sources and they give high power output in the range of 3–5 W to use in fiber-to-the-home as well as optical cable television networks. With the requirement for high output power in multichannel cost-efficient telecommunication systems, amplifier devices face some limitations during its operation at maximum operating power level. The major limitations are the thermal effects, damage thresholds, and available pump power. Effective thermal management is a better option to improve the pump power conversion efficiency and power scaling in high-power fiber amplifiers. Analytical and experimental investigation of two approaches for the thermal management of a commercial 3 W amplifier is discussed. The first approach considers a regular Al 6063 heat sink-heat spreader combination with forced air cooling. The structure of the heat sink is optimized and the performance is analyzed with Aluminum and copper material for the heat spreader. The second approach discusses a thermoelectric cooler-heat sink combination and the analysis results showed better thermal management during the high-temperature operation of the amplifier. Two heat sink materials are considered in the analysis and results are discussed in the paper. Considering the cost-effectiveness of the proposed solution, the thermoelectric cooler and Aluminum heat sink assembly are validated.

More than 5 kW counter tandem pumped fiber amplifier with near single-mode beam quality

We report on what we believe is the first demonstration of a monolithic counter tandem pumped ytterbium-doped fiber amplifier based on conventional double-clad fiber. At the maximum power of 5.03 kW, the amplifier delivered a near single-mode beam quality (M2 = 1.54), without stimulated Raman scattering effect or mode instability. In addition, we theoretically and experimentally investigated the impact of the 1080 nm signal laser from the amplifier on the 1018 nm fiber lasers used as pump sources. It revealed that even a small proportion of signal light coupled into a 1018 nm fiber laser cavity could cause a considerable power decline of the pump laser. Possible solutions to reduce the influence of signal light on pump sources were extensively discussed. Moreover, we experimentally confirmed the advantage in nonlinear effects mitigation of counter-pumping compared to co-pumping. This work proves the feasibility and superiority of the all-fiberized counter tandem pumping scheme, which could provide inspiration for future power scalability.

High power, tunable hybrid fiber/bulk laser at 1030 nm and parametric frequency conversion in the near and mid-infrared

We report on a high power, wavelength-agile, hybrid fiber-bulk laser, emitting up to 3.5 mJ 15 ns pulses at 1030 nm at 5 kHz repetition rate. This hybrid laser is composed of a commercial seed single-frequency fiber laser, tunable over several GHz, amplified in a dual-stage single-mode Ytterbium doped fiber amplifier, followed by two Yb:YAG solid crystal amplifiers. To illustrate the potential of such an architecture for future differential absorption lidar emitters, this hybrid source was used to pump an optical parametric amplifier (OPA) seeded by the idler at 3 \(\upmu\)m generated by a fixed nested cavity optical parametric oscillator (NesCOPO). The wavelength agility of the pump is transferred to the OPA signal beam to reach a fine tunability in the 1.5 \(\upmu\)m region. This fine tuning was used to measure the transmission spectrum of an acetylene gas cell.

Narrow Linewidth 49 W All Fiber Linearly Polarized Picosecond Laser Operating at 1016 nm

An all fiber linearly polarized narrow linewidth pulsed fiber laser operating at 1016 nm is demonstrated in a master oscillator power amplification (MOPA) configuration. Core-pumped double cladding ytterbium-doped large mode area fiber amplifiers are proposed as the pre-amplifiers to reduce the nonlinearity and the ASE. The laser exhibits 48.6 W average output power, ∼18 kW peak power, and 0.28 nm linewidth.