Излучательные характеристики мощных полупроводниковых лазеров (1060 нм) с узким мезаполосковым контактом на основе асимметричных гетероструктур AlGaAs/GaAs с широким волноводом

Light characteristics of narrow-stripe lasers (5.5 m) based on asymmetric AlGaAs/GaAs heterostructures are studied. It was shown that the maximum optical power achieved under continuous-wave (CW) operation is limited by thermal heating and reaches 1695 mW at a current of 2350 mA at +25°C, and the maximum efficiency reaches 54.8 %. By reducing the operating temperature to -8°C, we were able to increase the maximum power to 2 W. A peak power of 2930 mW was obtained under pulsed operation (pulse width 240 ns, amplitude 4230 mA). It is shown there is a region of an “optical dip” in the power profile with a low-efficiency lasing of a train of pulses of sub-ns duration under pulsed operation.

Одномодовые лазеры (1050 нм) мезаполосковой конструкции на основе гетероструктуры AlGaAs/GaAs со сверхузким волноводом

The radiation properties of single-mode lasers based on an AlGaAs/GaAs heterostructure with an ultra-narrow waveguide are studied. It is shown that the use of an ultra-narrow waveguide (100 nm) and thin (70 nm) wide-gap barriers at the waveguide/cladding interface improves the vertical divergence. The lateral and vertical divergences were 5 and 18.5 degrees, respectively, for the developed narrow-stripe (5.1 µm) single-mode lasers. An efficient single-mode operation up to a power of 200 mW is demonstrated. A further increase in current leads to the onset of higher-order modes, while the maximum optical power achieved under continuous-wave (CW) operation is limited by overheating and is 550 mW. The transfer to a pulsed operation (pulse width 200 ns) made it possible to raise the maximum peak optical power to 1500 mW.

Qualitative Inheritance of External Fruit Traits in Watermelon

Genes for watermelon [Citrullus lanatus (Thunb.) Matsumura & Nakai] fruit traits have been identified since the 1930s. We conducted a study of fruit traits including fruit stripe width, stripe color, rind color, fruit shape, and blossom end shape (concave vs. convex). Ten watermelon cultivars (inbred lines) were used as parents. Several new genes or alleles were discovered. A series of alleles at the g locus is proposed to explain the inheritance of fruit rind pattern: G (medium or dark solid green), gW (wide stripe), gM (medium stripe), gN (narrow stripe), and g (solid light green or gray). The dominance series is G > gW > gM > gN > g. Another series of alleles at the ob locus is proposed for the fruit shape: allele ObE for elongate fruit, which is the most dominant; allele ObR (not the same as the o gene for round) for the round fruit; and allele ob for oblong fruit, which is the most recessive. Gene csm is proposed for the clear stripe margin in the cultivar Red-N-Sweet and is recessive to the blurred stripe margin (Csm) in ‘Crimson Sweet’, ‘Allsweet’, and ‘Tendersweet Orange Flesh’.

Silver Nanowires Deposited on Grooved Surface as Bendable Resistance Sensor

In this paper, we present a simple bendable resistance sensor with silver nanowires (AgNWs) stripe coated on microgroove surfaces formed on a polyimide (PI) film. We adopted an anisotropic wetting manner to form a narrow stripe in order to improve the sensitivity of the resistance sensor. The ultraviolet (UV)-curable polymer NOA61 is firstly drop-coated on the substrate, and then imprinted by a groove-textured poly (dimethylsiloxane) (PDMS) template. After UV irradiation and de-molding, the surface is further treated with a UV-ozone (UVO) lamp, so that the grooved surface becomes more hydrophilic, which will promote the anisotropic wettability of AgNWs suspension and thereby deposition of AgNWs into uniform multi-layer stripe pattern. Moreover, the conductance with respect to the bending motion is measured. The most variation of conductance ΔG/G0 can reach about 200 % with bending radius of 2 mm.