An extremely low-threshold current of 6 mA in cw mode at 22 °C was achieved in 1.55-μm InGaAsP/InP buried heterostructure distributed feedback lasers with a first-order grating and a normal cavity length of 300 μm. These lasers exhibited an average differential efficiency of 30% total at 4 mW without any coating on the facets, and a T0 (25–70 °C) value of 55 K. A spectral linewidth as low as 8 MHz at cw mode was obtained. The lasers showed high-speed pulse modulation response to 2.4 Gb/s (NRZ).
A new type center aperture detection (CAD) magnetically induced super-resolution (MSR) disk is described. A magneto-static type CAD disk was already reported last year, and it improves readout stability without deteriorating the readout characteristics such as readout resolution by using a gadolinium intermediate layer instead of a non-magnetic layer. Our group studied the intermediate layer further, and realized the exchange coupling type CAD disk that has high-resolution and readout stability simultaneously by using GdFeCo intermediate layer. It has large tolerance to the external magnetic field at readout. The tolerance became about three times larger than the magneto-static coupling type CAD reported before.
Abstract-We designed the magnetic triple-layer disk by investigating the role of the intermediate layer. The maximum external magnetic field for writing and the maximum laser power for reading are examined by changing the composition and thickness of the intermediate layer. As a result, we obtained a magnetic triple layer disk which fits for practical use. Moreover, the capability for higher density recording is confirmed in the optimized triple-layer disk by investigating a bit error rate for a bit length of 0.8 J.l.m with (2,7) R.L.L. mark position recording.
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