Electron Beam Pumping Research Articles

Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System.

Powerful emitters of ultraviolet C (UVC) light in the wavelength range of 230-280 nm are necessary for the development of effective and safe optical disinfection technologies, highly sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The important advantages of these emitters are the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells of AlxGa1-xN/AlyGa1-yN (x = 0-0.5, y = 0.6-1), fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional (2D) quantum disks of GaN/AlN with a monolayer's (1 ML~0.25 nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and high-output UVC-optical powers.

2D-GaN/AlN Multiple Quantum Disks/Quantum Well Heterostructures for High-Power Electron-Beam Pumped UVC Emitters.

This article describes GaN/AlN heterostructures for ultraviolet-C (UVC) emitters with multiple (up to 400 periods) two-dimensional (2D)-quantum disk/quantum well structures with the same GaN nominal thicknesses of 1.5 and 16 ML-thick AlN barrier layers, which were grown by plasma-assisted molecular-beam epitaxy in a wide range of gallium and activated nitrogen flux ratios (Ga/N2*) on c-sapphire substrates. An increase in the Ga/N2* ratio from 1.1 to 2.2 made it possible to change the 2D-topography of the structures due to a transition from the mixed spiral and 2D-nucleation growth to a purely spiral growth. As a result, the emission energy (wavelength) could be varied from 5.21 eV (238 nm) to 4.68 eV (265 nm) owing to the correspondingly increased carrier localization energy. Using electron-beam pumping with a maximum pulse current of 2 A at an electron energy of 12.5 keV, a maximum output optical power of 50 W was achieved for the 265 nm structure, while the structure emitting at 238 nm demonstrated a power of 10 W.

Electron beam pumping improves the conversion efficiency of low-frequency photons radiated by perovskite quantum dots

This research argues that using an electron beam with high kinetic energy to pump perovskite quantum dots can significantly boost the efficiency of the low-frequency photon radiation conversion. Firstly, we measure the random lasing threshold and luminescence threshold of CsPbX 3 films pumped by an electron beam. Then, we simulate the spatial distribution of the electron beams in CsPbX 3 films. Combined with the above data, a low-frequency photon radiation conversion model based on the electron pumped perovskite quantum dots is presented. This could be a way to create a terahertz source with a high-power output or to multiply the terahertz power.

Semiconductor disk laser with a wavelength of 780 nm based on a MOCVD-grown Al x Ga1–x As/Al y Ga1–y As heterostructure with optical and electron beam pumping

A pulsed semiconductor disk laser based on the Al x Ga1 – x As/Al y Ga1 – y As structure with resonantly periodic gain and a built-in Bragg mirror emitting at a wavelength near 780 nm is studied. The laser characteristics are presented both for pumping by an electron beam and for optical pumping by laser diode radiation with a wavelength of 450 nm. Under pumping by an electron beam, a peak power of 4.4 W is achieved with a slope efficiency of over 10 %, while under optical pumping, the power is 0.2 W with a slope efficiency of 2.2 % and approximately the same cavity parameters. Possible reasons for the lower powers and efficiency under optical pumping are discussed.

Large-area far ultraviolet-C emission of Al0.73Ga0.27N/AlN multiple quantum wells using carbon nanotube based cold cathode electron-beam pumping

In this study, we demonstrated a far ultraviolet-C (far-UVC) emitter using Al0.73Ga0.27N/AlN multiple quantum wells (MQWs) by carbon nanotube based cold cathode electron-beam (C-beam) excitation. The Al0.73Ga0.27N/AlN MQW structure was grown on AlN/sapphire by high-temperature metal-organic chemical vapor deposition. The large-area far-UVC emission (276 mm2) was investigated using C-beam, as a function of anode voltage (VA) and anode current (IA), and the near-band-edge emission of Al0.73Ga0.27N/AlN MQWs was observed at a peak wavelength of 233 nm, with a VA of 4 kV, an IA of 0.5 mA. The results suggest that the large-area C-beam pumped far-UVC emitter could be a promising sterilization light source.

Random lasing of CsPbBr3 perovskite thin films pumped by modulated electron beam

Aiming at the application requirements of information optics, this Letter proposed a perovskite quantum dot random lasing pumping method suitable for high-speed modulation. At the same time, the luminescence characteristics of perovskite quantum dot films under electron beam pumping conditions are analyzed, and the random lasing mechanism of electron beam pumping CsPbBr3 quantum dot films is revealed. Finally, it is confirmed that perovskite quantum dots are easy to realize random lasing under electron beam pumping conditions.

Transport model for a transverse electron beam-pumped semiconductor laser

AbstractA transport model for a transverse electron beam-pumped semiconductor laser has been developed. The model incorporates spatial dependencies of the power deposition from the beam as well as a three-dimensional model of the gain medium and the field intensity of the photons produced by stimulated emission in the oscillation cavity. This model accounts for spatial inhomogeneities and has been solved for a variety of pumping strengths. The model was developed so that it can be benchmarked with electron beam pumping. The dominant mechanisms for the production of electron–hole pair production within the semiconductor material is similar to the dominant mechanisms for the production of electron–hole production using ion beams. Thus, the model can be extended to fission fragment ion pumping of semiconductor lasers in order to model a nuclear-pumped laser/reactor system.

Large area deep ultraviolet light of Al0.47Ga0.53N/Al0.56Ga0.44N multi quantum well with carbon nanotube electron beam pumping

Large area deep ultraviolet (DUV) light is generated by carbon nanotube (CNT) cold cathode electron beam (C-beam) irradiation on Al0.47Ga0.53N/Al0.56Ga0.44N multi quantum wells (MQWs) anode. We developed areal electron beam (EB) with CNT cold cathode emitters. The CNT emitters on silicon wafer were deposited with an area of 188 mm2, and these were vertically aligned and had conical structures. We optimized the C-beam irradiation conditions to effectively excite AlGaN MQWs. When AlGaN MQWs were excited using an anode voltage of 3 kV and an anode current of 0.8 mA, DUV with a wavelength of 278.7 nm was generated in a large area of 303 mm2. This DUV area is more than 11 times larger than the light emitting area of conventional EB pumped light sources and UV-LEDs.

Radiative Characteristics of Xe2Cl* Molecules under High-Energy Electron Pumping of Xe–CCl4 and Ar–Xe–CCl4 Gas Mixtures with a Low CCl4 Content

Spontaneous and stimulated emissions of Xe2Cl* triplex molecules upon excitation of Xe–CCl4 gas mixtures with a low CCl4 content by a pulsed high-energy electron beam have been experimentally studied. The electron energy is 150 keV, and the pump current pulse duration and amplitude are 5 ns and 5 A, respectively. Emission of an Xe2Cl excimer molecule in the wavelength range of 430–650 nm is shown to consist of 13 narrow vibrational bands with half-widths Δλ ~ 14 nm peaking at 399, 413, 431, 451, 472, 492, 510.3, 534.9, 540.9, 551.7, 564.4, 581.6, and 603 nm. Under the given pumping conditions, a regime of weakly amplified spontaneous emission is implemented at the energy deposition to the gas of ~200 W/cm3 on the axis of a 50‑mm cell and the electron beam pumping in the wavelength range of 450–550 nm. Spontaneous emission of the 42Г–12Г band of a Xe2Cl* excimer molecule at λmax = 486 nm was amplified by a factor of 60 in a 100‑cm cell under pumping of a dense 3He–Xe–CCl4 gas mixture by the 3He(n, p)3T nuclear reaction products at the energy deposition to the gas of ~5 mJ/cm3 in a cavity with the mirror reflections of ~99.4% (totally reflecting mirror) and 98.5% (output mirror).

Излучательные характеристики молекул Xe-=SUB=-2-=/SUB=-Cl-=SUP=-*-=/SUP=- при накачке пучком быстрых электронов газовых смесей Xe-CCl-=SUB=-4-=/SUB=- и Ar-Xe-CCl-=SUB=-4-=/SUB=- с низким содержанием CCl-=SUB=-4-=/SUB=-

AbstractSpontaneous and stimulated emissions of Xe_2Cl* triplex molecules upon excitation of Xe–CCl_4 gas mixtures with a low CCl_4 content by a pulsed high-energy electron beam have been experimentally studied. The electron energy is 150 keV, and the pump current pulse duration and amplitude are 5 ns and 5 A, respectively. Emission of an Xe_2Cl excimer molecule in the wavelength range of 430–650 nm is shown to consist of 13 narrow vibrational bands with half-widths Δλ ~ 14 nm peaking at 399, 413, 431, 451, 472, 492, 510.3, 534.9, 540.9, 551.7, 564.4, 581.6, and 603 nm. Under the given pumping conditions, a regime of weakly amplified spontaneous emission is implemented at the energy deposition to the gas of ~200 W/cm^3 on the axis of a 50‑mm cell and the electron beam pumping in the wavelength range of 450–550 nm. Spontaneous emission of the 4^2Г–1^2Г band of a Xe_2Cl* excimer molecule at λ_max = 486 nm was amplified by a factor of 60 in a 100‑cm cell under pumping of a dense ^3He–Xe–CCl_4 gas mixture by the ^3He( n , p )^3T nuclear reaction products at the energy deposition to the gas of ~5 mJ/cm^3 in a cavity with the mirror reflections of ~99.4% (totally reflecting mirror) and 98.5% (output mirror).

Optimization of Zn2SiO4 Anode Structure for Deep Ultraviolet Generation With Carbon Nanotube Emitters

Ultraviolet (UV) light is applied to various industrial and medical devices. In particular, deep UV light with short wavelengths could minimize the damage to human cells when it is used to virus and bacterial sterilization. We optimized the Zn2SiO4 anode structure to improve deep UV light generation with a carbon nanotube (CNT) cold cathode based electron beam (C-beam) pumping. Annealing at 1000 °C and 400 mTorr produces anode with the highest deep UV intensity. Using a 100-nm SiOx layer between Zn2SiO4 and quartz substrate, the intensity of deep UV light at a wavelength of 226 nm was increased by 1.8 times.

电子束泵浦XeCl准分子激光器输出特性

电子束泵浦XeCl准分子激光器输出特性

Demonstration of electron beam laser excitation in the UV range using a GaN/AlGaN multiquantum well active layer

This study investigated electron beam laser excitation in the UV region using a GaN/AlGaN multiquantum well (MQW) active layer. Laser emission was observed when the GaN/AlGaN MQW was excited by an electron beam, with a wavelength of approximately 353 nm and a threshold power density of 230 kW/cm2. A comparison of optical pumping and electron beam pumping demonstrated that the rate of generation of electron-hole pairs when using electron beam excitation was approximately one quarter that of light excitation.

Design of Electron Beam Welding Vacuum Chamber for Collar Rings in CFETR Windows

China Fusion Engineering Test Reactor window collar has a very complex three-dimensional structure, because of its large size, in the window and collar welding cannot be completed after the overall processing, therefore, requires that the welding ring has deformation of small, high precision welding, and reliable welding quality. As a kind of high-energy beam welding method, vacuum electron beam welding can ensure the welding quality of the collar of the vacuum chamber. Therefore, a vacuum electron beam welding system will be used to weld the window collar of the vacuum chamber. The vacuum electron beam welding system consists of vacuum chamber, electron beam welding gun, movement system, pumping system and other major components. Because the size of the vacuum chamber is 7200 × 3550 × 2600 mm, its working stability is very important. Therefore, the structure of the vacuum chamber is designed and its working state is simulated and analyzed by ANSYS finite element analysis. The structure of the vacuum chamber is optimized. And the pumping time of this vacuum pumping system is calculated in detail. The design provides a reference.

Pulsed electron-beam-pumped laser based on AlGaN/InGaN/GaN quantum-well heterostructure

The parameters of pulsed blue-violet ( at ) lasers based on an AlGaN/InGaN/GaN structure with five InGaN quantum wells and transverse electron-beam pumping are studied. At room temperature of the active element, the minimum electron energy was and the minimum threshold electron beam current density was at an electron energy of .

E‐beam pumped mid‐UV sources based on MBE‐grown AlGaN MQW

A 60 mW output power has been achieved in mid‐UV (λ = 270 nm) spontaneous sources with electron‐beam pulse‐scanning pumping, fabricated from AlGaN MQW heterostructures grown by PA MBE on c‐Al2O3 substrates. Under the CW pumping at much lower excitation power density the mid‐UV sources demonstrate a 4.7 mW output power. In that regime the power efficiency of the structures is about 0.24%, while their internal quantum efficiency is estimated to be as high as 50%.

Amplification and formation of femtosecond laser single pulses upon the high-current electron beam pumping of Ti:Al2O3 crystals

Features of the high-power nanosecond X-ray and electronic excitation of Ti:Al2O3 crystals are investigated. It is shown that the coefficient for the single-pass amplification of femtosecond laser emission reaches 11 upon the high-current nanosecond electron beam pumping of Ti:Al2O3 crystals, along with the synchronous emission of a femtosecond laser single pulse under the action of the induced accompanying hypersonic wave.

Quantum fluid model of coherent stimulated radiation by a dense relativistic cold electron beam

Using a quantum fluid model, the linear dispersion relation for FEL pumped by a short wavelength laser wiggler is deduced. Subsequently, a new quantum corrected resonance condition is obtained. It is shown that, in the limit of low energy electron beam and low frequency pump, the quantum recoil effect can be neglected, recovering the classical FEL resonance condition, ks=4kwγ2. On the other hand, for short wavelength and high energy electron beam, the quantum recoil effect becomes strong and the resonance condition turns into ks=2kw/ƛcγ3/2, with ƛc being the reduced Compton wavelength. As a result, a set of nonlinear coupled equations, which describes the quantum FEL dynamics as a three-wave interaction, is obtained. Neglecting wave propagation effects, this set of equations is solved numerically and results are presented.

A scanning pulse-periodic laser based on heterostructures containing ZnSe with electron beam pumping

Characteristics of a scanning pulsed green laser based on heterostructures containing ZnSe pumped by an electron beam with 200-ns duration and 8-keV energy are studied. If the active element is at room temperature, the scanning frequency is 20 Hz, and the repetition rate is 3 kHz, the average power of laser radiation is 1.6 mW, provided that the pulsed power is 2.7 W.

Catastrophic degradation of pulsed lasers based on AlGaAs/InGaAs/GaAs heterostructures with electron-beam pumping

Catastrophic degradation of pulsed lasers based on InGaAs/AlGaAs/GaAs structures with different design of the active domain with transverse pumping by the electron beam at T = 300 K is studied. In lasers based on structures with a InGaAs single quantum well and with seven quantum wells, the maximal values of pulsed power are 70–90 and 10–20 W, respectively.