Lasers Benefit Data Storage, Near-Field Optics
According to researchers from Bell Laboratories in Murray Hill, N.J., lasers with a very small aperture promise to advance near-field optics and to enable data storage densities of more than 500 Gb/in.2, or 100 times the current densities. The team demonstrated a 980-nm laser diode with a 250-nm-sq aperture by recording and reading marks with a 7.5-Gb/in.2 density at a 24-Mb/s data rate -- three times the density of a DVD-ROM disk at twice the speed.
Any laser diode can accept the very small aperture design. A focused ion beam simply etches an aperture of the desired size into a metal coating deposited on the front facet of the diode. The researchers have produced the devices with square apertures of 50 to 400 nm on a side.
The lasers display an output 104 times that of tapered, metal-coated optical fiber probes, the most common light source for near-field scanning apertureless microscopy. A higher-power light source may increase the signal-to-noise ratios and data rates of current applications as well as lead to the development of compact near-field microscopes.
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