Photonic-crystal-based technology is a hot research topic for its ability to enable tiny, controllable circuits, laser sources, and other optoelectronics devices. To that end, opal photonic-crystal structures may facilitate realization of low-threshold, tunable, single-mode lasing, say researchers at Hokkaido University (Kyoto, Japan) and Sanyo Chemical Industries (Kyoto). The group used a frequency-doubled nanosecond Nd:YAG laser emitting at 532 nm and a repetition rate of 10 Hz to intensely pump three-dimensional zirconium dioxide inverse opal photonic-crystal structures infused with various liquid rhodamine dyes. Zirconia inverse opals have a higher refractive index and are more robust than fabricated polystyrene direct opals, and can withstand very high optical pump irradiances.
The group observed emission peaks at 572, 588, and 612 nm, each with a spectral full-width half-maximum of 1 nm or less. The peak wavelengths and spectral widths were independent of pump power, which helped lead to the conclusion of single-mode lasing. The lasing wavelengths fell within the photonic stop band of the opal structure but outside the Bragg wavelength, which indicates tunability may be possible around the Bragg wavelength. Contact Horoaki Misawa at [email protected].