[en] Low specific on-resistance, high packing densities, and large blocking voltage capabilities have all made U-shaped trench-gated metal-oxide-Si field-effect transistor (UMOSFET) the leading candidate in power electronic applications. However, hot carrier and Fowler Nordheim stresses are major reliability concerns for UMOSFETs. In studying the effects of these stresses on device lifetime, charge pumping (CP) has proven to be a versatile transistor characterization technique. For its application 'conventional' CP, however, needs four terminal transistors and features the substrate current as its main output. Often a UMOSFET has only three terminals and no substrate contact is included in the device. We report on an adaptation of the CP technique, which renders it applicable on three-terminal UMOSFETs and other three-terminal transistors. The three-terminal CP is applied to n-channel UMOSFETs, and is used to evaluate the effects of electrical stresses applied to the UMOSFETs

[en] The service life of solitary heterolasers at a temperature of 50⁰C (P = 1W, λ = 0.98 - 0.99 μm) is studied. The maximum service life of heterolasers under such working conditions is 60000 hours for an average pumping current 1.5 A. (lasers and amplifiers)

[en] We report on the direct generation of optical vortex lattice (OVL) modes from a diode-pumped Pr³⁺:LiYF₄ (Pr:YLF) laser achieved by employing off-axis (transverse) and defocused (longitudinal) pumping geometries in the laser medium. OVL modes with more than 40 phase singularities are generated. The experimentally observed OVL modes are well supported by a theoretical analysis based on the superposition of Hermite-Gaussian modes. We also discuss the intracavity frequency doubling of the OVL modes. The proposed OVL mode laser system can be applied to fundamental optical science and advanced material engineering. (paper)

[en] A high-power Er–Yb codoped fiber amplifier (EYDFA) with an Yb-band resonant cavity is investigated. By introducing a linear resonant cavity formed by a pair of high-reflection double-clad fiber Bragg gratings, the Yb-ASE problem of high-power pumped EYDFAs can be resolved and the efficiency of the amplifier can be notably improved. At a pump power of ∼17 W, an output power of 7.25 W was experimentally achieved. The pump conversion efficiency and slope efficiency relative to the applied pump power are ∼42.6% and ∼45.6%, respectively. Moreover, due to the gain-clamping effect of the Yb cavity, the gain flatness of the amplifier is also evidently improved. (letter)

[en] We study theoretically semiconductor optical amplifier (SOA) length effects on gain dynamics when a short saturating pulse (pump) is either co- or counter-propagative with the probe. More specifically, we focus our attention on SOA recovery dynamics and gain overshoot. Analysis is also given when the input probe power and input pump energy are increased for different SOA lengths

[en] In recent years, there have been a significant number of demonstrations of small metallic and plasmonic lasers. The vast majority of these demonstrations have been for optically pumped devices. Electrically pumped devices are advantageous for applications and could demonstrate concepts not amenable for optical pumping. However, there have been relatively few demonstrations of electrically pumped small metal cavity lasers. This lack of results is due to the following reasons: there are limited types of electrically pumped gain media available; there is a significantly greater level of complexity required in the fabrication of electrically pumped devices; finally, the required components for electrical pumping restrict cavity design options and furthermore make it intrinsically more difficult to achieve lasing. This review looks at the motivation for electrically pumped nanolasers, the key issues that need addressing for them to be realized, the results that have been achieved so far including devices where lasing has not been achieved, and potential new directions that could be pursued. (topical review)

[en] The design and operation of a large, repetitively pulsed e-beam laser is described. The laser is capable of 100 Hz operation and has an average power of over 1 kW

[en] We report the first demonstration of an efficient, high power, resonantly (in-band) diode-cladding-pumped Tm-doped fiber laser operating on the ³F₄  ⇒  ³H₆ transition of Tm³⁺ ion. The laser, pumped by a fiber coupled laser diode module at ∼1620 nm, delivered ∼15 W of power at 1930 nm with a slope efficiency of 67% versus the absorbed pump power. This presents, to the best of our knowledge, the highest slope efficiency and the highest output power reported so far for resonantly diode-cladding-pumped 2 µ m fiber lasers based on double-clad Tm-doped silica fibers. These very preliminary results, obtained with commercial double-clad Tm-doped fibers, unoptimized for in-band pumping at the peak of resonant absorption, indicate a very high potential of resonantly diode-cladding-pumped Tm fiber lasers for major power scaling unaffected by photodarkening. Fiber optimization for resonant pumping at the maximum of the Tm^3+   3H₆  ⇒  ³F₄ absorption band in silica (1610–1710 nm) can lead to a new generation of Tm fiber lasers with power and wall-plug efficiency, competing with those of high power tandem-pumped Tm-doped fiber lasers, but potentially with a lighter weight and smaller dimensions. (letter)

[en] A diode-end-pumped passively Q -switched Nd:LuAG laser at 1442.6 nm was demonstrated with a V³⁺:YAG crystal as the saturable absorber. Under continuous-wave (CW) operation, the maximum output power of 1.83 W was obtained with an absorbed pumping power of 11.1 W. The corresponding optical-to-optical conversion efficiency was 16.5%. Under Q -switched operation, the maximum average output power of 424 mW was obtained at the same pumping power. The pulse duration and pulse repetition rate were 72 ns and 17.4 kHz, respectively. (letter)

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