Eu 3+ -doped SiO 2 , Al 2 O 3 -SiO 2 , and P 2 O 5 -SiO 2 glasses were prepared by a sol-gel method from metal alkoxides, and their persistent spectral hole burning (PSHB) properties were investigated in relation to the local environment of the Eu 3+ ions in glass. Fluorescence line narrowing spectra indicated that Eu 3+ clustering occurred in SiO 2 glass. The addition of Al 2 O 3 or P 2 O 5 promoted better dispersion of Eu 3+ in the glass matrix, though two sites for Eu 3+ ions seemed to exist in Al 2 O 3 -SiO 2 glass. The holes were burned in the 7 F 0 f 5 D 0 line of the Eu 3+ ions using a Rhodamine 6G dye laser, the hole area of which increased proportionally with the content of hydroxyl groups. The holes that were burned by the photoinduced rearrangement of the OH bonds were thermally refilled and the barrier height of the burnt-state was determined as 0.14, 0.30, and 0.40 eV for P 2 O 5 -SiO 2 , SiO 2 , and Al 2 O 3 -SiO 2 glass, respectively.

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We report on the long-term reliable CW operation of high-power and high-efficiency 915-nm broad-area laser diodes (BA-LDs). An output power of over 20 W and a maximum power-conversion efficiency of over 65% have been marked at a heat-sink temperature of 20 ºC. Stable operations of over 5000 h have also been achieved for the 915-nm and 976-nm BA-LDs with CW output powers of 20 W, respectively. The window structure with a band gap difference of 100 meV provides the reliable operation at the high-output power range.

We report on a GaAs-based high-power-density vertical-cavity surface-emitting laser diode (VCSEL) array with ion-implanted isolated current apertures. A peak output power of 40.6 W has been achieved from the VCSEL array with seven emitters under 100-ns-pulse operation. This is the first demonstration of a ten-watt-class output power for a VCSEL array with ion-implanted isolated current aperture configuration. The corresponding power-density is estimated to be 73.8 kW/cm 2 , which is three times greater than the record power-density of the short-pulseoperated oxide-confined VCSEL. #