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Electrically tunable interband cascade lasers are demonstrated with a wide tuning range of about 280 cm-1 (34meV in energy or 630 nm in wavelength) near 4.5 μm and about 180 cm-1 (22meV or 900 nm) near 7 μm wavelengths. The laser structures are designed such that the heating and Stark effects act together to enhance the red-shift of the lasing wavelength with current injection to achieve wide tunability. The control and manipulation of the tuning range and rate are discussed. [ABSTRACT FROM AUTHOR]

Effects of laser energy density (LED) on densities and surface roughness of AlSi10Mg samples processed by selective laser melting were studied. The densification behaviors of the SLM manufactured AlSi10Mg samples at different LEDs were characterized by a solid densitometer, an industrial X-ray and CT detection system. A field emission scanning electron microscope, an automatic optical measuring system, and a surface profiler were used for measurements of surface roughness. The results show that relatively high density can be obtained with the point distance of 80–105 μm and the exposure time of 140–160 μs. The LED has an important influence on the surface morphology of the forming part, too high LED may lead to balling effect, while too low LED tends to produce defects, such as porosity and microcrack, and then affect surface roughness and porosities of the parts finally. [ABSTRACT FROM AUTHOR]

Electrophysical approach to estimation of conditions for efficient pumping of active medium of lasers on selfterminating transitions of metal atoms in a gas discharge tube with electrodes in cold buffer zones is used. Existence of processes that enhance the effect of the well-known mechanism of limitation of radiation frequency and energy characteristics caused by the presence of a pre-pulse electron concentration in the discharge circuit of lasers on self-terminating transitions of metal atoms is demonstrated. The mechanism of influence of these processes on frequency and energy characteristics of lasers on self-terminating transitions of metal atoms and the technical methods of neutralization of these processes are considered. It is shown that the practical efficiency of a copper vapor laser can attain ~10% under conditions of neutralization of these processes. [ABSTRACT FROM AUTHOR]

Research on semiconductor nanowires underlies the development of the miniaturization of laser devices with low cost and low energy consumption. In general, nanowire lasers are made of direct band gap semiconductors, e.g., GaN, ZnO and CdS, and their band-edge emissions are used to achieve optically pumped laser emission. In addition to the existing class of nanowire lasers, we here show that air-annealed micrometer-sized MgO cubic crystals with well-defined facets exhibit room-temperature stimulated emission at 394 nm under pulsed laser pumping at ~350 nm. Surface midgap states are assumed to be responsible for the excitation and emission processes. The present findings will not only provide opportunities for the development of miniaturized lasers composed of insulating oxides, but will also open up functionality in various families of cubic crystalline materials. [ABSTRACT FROM AUTHOR]

A low power-consumption distributed feedback quantum cascade laser (DFB-QCL) is developed for gas-sensing in 7 μm wavelength region. The threshold power-consumption was as low as 0.93 W with the sufficient output power of 20 mW at 20°C under continuous-wave condition. In addition, it maintained a single-mode operation between -40 and 50°C without a mode-hopping, leading to a total wavelength shift of 66 nm. This DFB-QCL would be suitable for gas-sensing application. [ABSTRACT FROM AUTHOR]

A hybrid quantum well/quantum dot active region is used to obtain simultaneous three-state lasing at room temperature, via ground state and first excited state transitions of the quantum dots and the lowest energy transition of a single quantum well. The device exhibits a threshold current density of 1125 A/cm2 for achieving simultaneous three-state lasing over ∼160 nm. [ABSTRACT FROM AUTHOR]

Presented are narrow-ridge, singlemode (λ=4.49 µm) quantum cascade lasers with low power consumption in continuous-wave operation. Episide up mounted 3 µm-wide and 1 mm-long devices with high-reflectivity backside coating show an electrical dissipation at laser threshold as low as 840 mW at 20°C. The devices can be tuned singlemode and mode-hop free between -30°C and +50°C and in a range of injected electrical power of 0.7 and 1.3 W with a sidemode suppression ratio better than 27 dB. [ABSTRACT FROM AUTHOR]