We have been developing high-speed write/read techniques for Blu-ray discs. We carried out 1–12× write/read tests on a phase-change Blu-ray write-once disc using an improved tester, an adaptive partial-response maximum-likelihood (PRML) technique, and a new write adjustment method. Sufficiently good limit equalizer jitter values of less than 6.5% were obtained under all write-speed conditions. Good bit error rates of less than 10-6 and fair power margins of more than ±10% were obtained under all write/read speed conditions.

We developed read/write technology for high-density optical data storage of 50 GB/layer at a data transfer rate of 108 Mbps. We demonstrated the writing and reading capabilities of a 50 GB/layer optical disk recording system at 36 Mbps with a sufficient power margin, using a three-beam crosstalk canceller with optical response equalizers, using a phase-change write-once disk. Bit error rates were below 1×10-4 at 108 Mbps. Experimental results showed that the technology realizes writing and reading densities two times higher and data transfer rates three times higher than those of Blu-ray with a simple optical component such as Blu-ray.

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The Mario Schenberg gravitational wave detector has been constructed at its site in the Physics Institute of the University of São Paulo as programmed by the Brazilian Graviton Project, under the full support of FAPESP (the São Paulo State Foundation for Research Support). We are preparing it for a first commissioning run of the spherical antenna at 4.2 K with three parametric transducers and an initial target sensitivity of h ∼ 2 × 10 −21 Hz −1/2 in a 60 Hz bandwidth around 3.2 kHz. Here we present the status of this project.PACS numbers: 04.80.Nn, 95.55.Ym