This paper presents a novel direct-metal-interconnect hybrid integration method for the fabrication of low cost and highefficiency multijunction solar cells without being constrained by lattice matching requirements. It also incorporates the areal current matching technique that is essential in mitigating the adverse effects of current limiting by the Si subcell to achieve maximum possible efficiency. A GaInP/InGaAs/Si triple-junction solar cell has been demonstrated, with a 2-terminal estimated efficiency of 25.5% tested under a filtered Xe arc lamp with the light intensity set to 100 mW/cm 2 . The cell shows promising thermal reliability, as well as potential for operation under concentrated illumination.Index Terms-Current matching, III-V on Si, multijunction (MJ) solar cell, photovoltaic (PV), solar spectrum.

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An AC-driven powder electroluminescent (EL) device has been achieved by constructing a CuO nanowire-Zn GeO :Mn phosphor heterogeneous junction. The CuO nanowires enhance the local electric field, resulting in electroluminescence of an oxide-based phosphor in EL devices owing to field injection at the nanowire tips. The CuO nanowire array was synthesized by an in situ thermal oxidation method at 400 °C in air and employed as an electric field enhancement layer in the EL device. The heterogeneous structures were created through drop coating of a phosphor suspension on the CuO nanowire array. The initial EL device tests show good luminescent performance with very promising brightness maintenance for over 360 h, with a loss of luminescent intensity of under 1 % at over 10 cd m luminance. The fabrication method offers the prospect of simple, low-cost, large-scale EL devices with the potential to solve the limited operational lifetime of sulfide-based AC powder EL devices.

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External cavity semiconductor lasers with a fiber Bragg grating in multimode fiber are studied experimentally. Coupling efficiency of >92% and single longitudinal mode operation with side-mode-suppression ratio of >40 dB are achieved.