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To better understand the influence of the microstructural characteristics on the mechanical properties of Fe-Cr22-Ni25-Nbxaustenitic stainless steel (ASS-Nbx), the mechanical properties were investigated. Nb addition was conducted with four different amounts: 0, 0.29, 0.58 and 0.86%. With the increasing Nb content, the mean grain size for the Fe-Cr-Ni-based alloys decreased, while the size of Nb precipitate increased. Owing to the different microstructural characteristics, their mechanical properties were altered. The highest tensile strength was obtained for ASS-Nb0.29alloy. However, with the increasing Nb content in ASS-Nb0.29–0.86alloys, the tensile strength decreases despite the grain refinement. The mechanical properties of the ASS-Nb alloys were influenced by the Nb precipitation hardening and the grain boundary cohesive strength, arising from the size of Nb precipitations.

To better understand the influence of the microstructural characteristics on the mechanical properties of Fe-Cr22-Ni25-Nbxaustenitic stainless steel (ASS-Nbx), the mechanical properties were investigated. Nb addition was conducted with four different amounts: 0, 0.29, 0.58 and 0.86%. With the increasing Nb content, the mean grain size for the Fe-Cr-Ni-based alloys decreased, while the size of Nb precipitate increased. Owing to the different microstructural characteristics, their mechanical properties were altered. The highest tensile strength was obtained for ASS-Nb0.29alloy. However, with the increasing Nb content in ASS-Nb0.29–0.86alloys, the tensile strength decreases despite the grain refinement. The mechanical properties of the ASS-Nb alloys were influenced by the Nb precipitation hardening and the grain boundary cohesive strength, arising from the size of Nb precipitations.

The strain induced martensitic transformation (SMT) of the austenite stainless steel (SUS 304) under cyclic loading and static loading was investigated directly using electron backscattered diffraction. Two different SMT characteristics are observed, which are attributed to the differences of plastic and twinning deformation. The maximum cyclic stress has a strong influence on the SMT. The total area fraction of the Fe-a' phase increases significantly when the maximum cyclic load is >80 sUTS. In other words, the SMT is apparently absent when the samples are loaded with less than smax?=?70 sUTS, although such samples are fractured completely. Moreover, there is a clear Rratio effect on the SMT. For example, the loading condition R?=?-1 gives rise to a strong SMT compared to R?=?0·1 due to the more severe strain caused by the compressive stress. In contrast, no clear frequency effect (1 versus 30 Hz) on the SMT is detected, which may be attributed to the same maximum cyclic stress. Like the SMT characteristics under cyclic loading, the proportion of Fe-a' phase shows no clear increase until the sample is loaded statically to a tensile stress <70 sUTS.

To better understand the material properties of lead zirconate titanate (PZT) ceramics, the influence of domain wall characteristics on the electrical and mechanical properties of PZT ceramics has been investigated. To obtain various domain wall characteristics, the poling process was carried out with different patterns with respect to the PZT ceramic. The domain walls were aligned in the PZT ceramic in the direction perpendicular to the poling direction. Such domain wall characteristic produced different crack growth behaviours. The crack growth occurred mainly along the domain walls of {110} for a31(crack growth direction perpendicular to the poling direction) because of the high stress concentration between the domain walls. In contrast, the crack propagated along both domain walls and grain boundaries for a33(crack growth direction parallel to the poling direction), leading to high crack growth resistance and good mechanical properties. The fracture toughness KICvalues for the PZT ceramics in the a31and a33directions were about 0·5 and 2·6 MPa m1/2respectively. It also appeared that the domain walls collapsed when a number of poling processes are conducted along different directions. These PZT ceramics had high mechanical properties due to the low stress concentrations.

To better understand the material damage of lead zirconate titanate (PZT) ceramics, fatigue tests have been carried out using a newly proposed testing system. The material damage was evaluated with the change in sonar intensity from the ceramics, where a sensing control was operated using a condenser microphone system. This testing system produces cyclic loading with a wide range of fatigue frequencies: 1 Hz–72 kHz. The influence of fatigue frequency on the fatigue properties of a PZT ceramic has been investigated, and it appeared that the fatigue strength is not linearly correlated with the fatigue frequency. The reason for this is due to the resonance caused by the oscillation. Thus, the fatigue frequency can change the severity of sample vibration. The extent of sample vibration is associated with the sonar intensity from the ceramic, which is linearly related to the crack growth rate. Details of the resonance fatigue properties have been systematically examined.

A novel optical receiver module using a plastic package, a glass V-groove substrate, an edge-illuminated refracting facet photodiode and a Si bipolar preamplifier IC has been developed. Its signal lines were designed using a three-dimensional electromagnetic field analysis. For a fabricated module, a frequency response of 7.7 4;GHz and a sensitivity of less than −14 4;dBm at 10 4;Gbit/s were achieved.

A 10 Gbit/s optical receiver module using a Si-bipolar IC has been developed. For low power and low cost, a pure Si-bipolar IC is used in place of a GaAs IC, which is commonly used for over 10 Gbit/s. To widen the frequency bandwidth, multifeedback techniques and a two-stage buffer configuration are used in the preamplifier IC. In addition, a differential circuit configuration is used for stable operation at high frequency. The IC was fabricated using 0.25 µm Si-bipolar technology. The module exhibits sensitivity of < –16 dBm for 10 Gbit/s data with an input dynamic range > 15 dB. Small power consumption of 410 mW is achieved with the single power-supply voltage of +5 V.

A gain coefficient of 11.0 dB/mW is obtained using 0.98 μm laser diode pumped erbium-doped fibre amplifiers with a low erbium concentration of 81 ppm and a high relative refractive index difference of 1.88%.

A small fibre amplifier module pumped by a 0.98 μm LD has been fabricated. Using a low erbium content fibre with a 4.9 dB/mW gain coefficient, the module attained 33 dB gain at 1.535 μm with only 80 mA drive current.

High-power GalnAs strained quantum well lasers with an emission wavelength of 0.98μ, suitable for Er3+-doped fibre amplifier pumping, have been fabricated. A threshold current of 15 mA and a peak output power as high as 85 mW have been obtained for the ridge waveguide structure with AR/HR facet coating. Highly efficient pumping for the 1.536 μm signals has been confirmed.

A small-sized, low-cost, uncooled and directly modulated 10 Gbit/s 1.3 µm DFB-LD module has been developed. New designs for both the electrical configuration and the optical coupling system in the module enable the first-ever 10 Gbit/s operation in a 0.5 cc ceramic package. The module meets all specifications of the principal LAN/WAN systems such as SDH/SONET and 10 Gbit Ethernet.

Temperature dependence of the gain at 1.536 μm in Er3+-doped fibre are reported for 0.98 and 1.48 μm pumping. The fibre lengths at which gain is temperature insensitive are found for both pump wavelengths. The temperature insensitive gain characteristics for 0.98 μm and 1.48 μm pumping are demonstrated to fibres tuned to their temperature insensitive lengths.

The authors propose a novel multiplexing technique that employs an optical ASK/FSK signal converter. Successful modulation and demodulation of 622 Mbit/s ASK signals is demonstrated using this technique; no error floor in the bit error rate performance is detected.