The long-term performance of two active hydrogen masers developed at the National Measurement Laboratory of the CSIRO is presented. Six years of comparisons between the masers, the United States Naval Observatory (USNO) and the Bureau International des Poids et Mesures (BIPM) are summarized. Operating as independent clocks the masers showed outstanding long-term performance and consistently high weightings in the coordination of major time-keeping centres carried out by the BIPM.

Optical injection locking was experimentally performed using a 38-GHz-band InP-based HEMT MMIC oscillator and a 1.55-m lightwave. Two optical modulation schemes were compared for optical injection locking, and no difference was found except for the optical modulation frequency. With suppressed carrier modulation of the lightwave, phase noise of less than 73.2 dBc/Hz at a 10-kHz frequency offset and a 14-MHz locking range were achieved.

We have already developed and reported the high-definition digital-versatile-disk read-only-memory system of capacity 15 Gbytes using a blue laser and new signal processing technique. On the other hand, a high numerical-aperture system has been reported of numerical-aperture 0.85 and cover layer thickness 0.1 mm. In this paper, we examined the increase in capacity on application of our signal processing technique to the high numerical-aperture system using computer simulation. As a result, we found that a 25 Gbytes read-only-memory disk system had sufficient system margins on applying the limit equalizer and the adaptive tangential equalizer. Furthermore, if the crosstalk canceler is applied, we may achieve a system of capacity larger than 25 Gbytes.

The annealing and etching effects of Pt/Bi 3:15 Nd 0:85 Ti 3 O 12 /Pt ferroelectric capacitors were studied. Bi 3:15 Nd 0:85 Ti 3 O 12 (BNdT) thin films were obtained by a sol-gel method. At an annealing temperature of 650 C, BNdT films crystallized well in nitrogen atmosphere, but remained amorphous in oxygen atmosphere. For capacitor fabrication, Pt top layers were etched by ion beam etch (IBE) to form top electrodes, and the BNdT ferroelectric films were etched by reactive ion etch (RIE) utilizing two different gases: SF 6 and HC 2 ClF 4 . Degradation was discovered after top electrode etching, and could be partly recovered by rapid thermal annealing in oxygen at 650 C. RIE etching damage was not prominent in both groups, though SF 6 etched group was a bit superior to HC 2 ClF 4 group. Nevertheless, HC 2 ClF 4 group became noticeable inferior to SF 6 group after a furnace annealing in nitrogen at 650 C for 40 min. This was attributed to the influence of hydrogen, which was induced by RIE process in HC 2 ClF 4 group. Instead, when oxygen was employed as the atmosphere of furnace annealing, both groups finally possessed similar ferroelectric properties, namely the RIE etching damage in HC 2 ClF 4 group had been recovered.

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