We report the fabrication of InGaN/GaN nanorod light-emitting diodes (LEDs) using inductively coupled plasma reactive-ion etching (ICP-RIE) and a photo-enhanced chemical (PEC) wet oxidation process via self-assembled Ni nanomasks. An enhancement by a factor of six times in photoluminescence (PL) intensities of nanorods made with the PEC process was achieved in comparison to that of the as-grown structure. The peak wavelength observed from PL measurement showed a blue shift of 3.8 nm for the nanorods made without the PEC oxidation process and 8.6 nm for the nanorods made with the PEC oxidation process from that of the as-grown LED sample. In addition, we have demonstrated electrically pumped nanorod LEDs with the electroluminescence spectrum showing more efficiency and a 10.5 nm blue-shifted peak with respect to the as-grown LED sample.

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We report efficient generation of cw yellow light by use of single-pass sum-frequency mixing from a diode-pumped Nd:YVO(4) dual-wavelength laser with periodically poled lithium niobate. A diode-pumped Nd:YVO(4) dual-wavelength laser is implemented with a three-mirror cavity, and the optimum oscillation condition is obtained from theoretical analysis. We extracted 78 mW of power at 593 nm from 1.2 W at 1064 nm and from 1.0 W at 1342 nm in a beam with excellent quality. The output power could probably be increased to ~92 mW by antireflection coating of the crystal.

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Characteristics of GaN-based light-emitting diodes ͑LEDs͒ grown on the chemical wet-etched patterned sapphire substrates ͑CWE-PSS͒ with different crystallography-etched facets were investigated. An improvement of 40% on the overall quantum efficiency was achieved by adopting this CWE-PSS scheme. A Monte Carlo ray-tracing method was employed to derive the optimized condition of sapphire etching time, and the calculated result demonstrated the same trend with real device measurement. Adopting the CWE-PSS in LEDs could not only improve the epitaxial quality but also increase the extraction quantum efficiency due to crystallography-etched facets efficiently scattering the guided light to enter the escape cone on the top of device surfaces. Finally, we observed better aging behaviors of CWE-PSS LEDs, which could be due to the reduction of threading dislocations of the epitaxial layers.