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A polarization-insensitive monolithic 40-Gbps semiconductor optical amplifier (SOA)-Mach-Zehnder interferometer wavelength converter has been developed. Based on the photon-electron rate equation, we optimized the dimensions of the waveguide structure to maximize the field confinement in the active layer. An InGaAsP active layer with narrow SOA waveguide effectively enables polarization-insensitive high-speed wavelength conversion. High-precision wafer processing technique enabled the fabrication of submicrometer-wide active waveguides with low current leakage. Input waveguide arrays were fabricated at intervals of 25 mum and mounted in a module with two-lens aspherical lens optics. The 40-Gbps nonreturn-to-zero wavelength conversion experiment demonstrates a clear eye opening over full C-band operation [ABSTRACT FROM PUBLISHER]

A novel all-optical modulation-format conversion from nonreturn-to-zero on-off keying (NRZ-OOK) to return-to-zero binary phase-shift keying (RZ-BPSK) is proposed. A Mach-Zehnder interferometric (MZI) wavelength converter consisting of integrated semiconductor optical amplifiers (SOAs) is utilized to implement the proposed format conversion. Error-free operation at a bit rate of 10.7 Gb/s is experimentally demonstrated in order to show the feasibility of the proposed scheme. The received sensitivity of the converted signal is improved by 2.9 dB compared with a back-to-back NRZ-OOK signal at BER=10 -9. In addition, a reasonable dispersion tolerance of the converted signal up to plusmn500 ps/nm is observed. The numerical simulation based upon the carrier-rate equation verifies the experimental results [ABSTRACT FROM PUBLISHER]

The authors developed an InP photodiode (PD) module integrated with an InP HBT preamplifier IC by using an Au stud bump. Theoretical analysis shows that the deviation of the group delay linearly increases in the inductance between the PD and IC. The flip-chip bonding based on the Au stud bump effectively reduces the inductance without sacrificing the individual device performance and reliability. Experimental results show that this technique is suitable for the receiver modules designed for applications with a bandwidth greater than 40 Gb/s [ABSTRACT FROM PUBLISHER]

Individual adult Perkinsiella saccharicida reared on sugarcane infected with Fiji disease virus (FDV) were confined on healthy plants for 7 days to test for virus transmission and were then sacrificed and assayed for the presence of FDV-specific structures by immunoelectron microscopy. Only 15% of the insects contained FDV antigens and 6% transmitted the virus. FDV-specific antigens were detected in individual planthoppers by immuno-osmophoretic and enzyme-linked immunosorbent assays about as efficiently as by immunoelectron microscopy. The possible reasons for the inefficient acquisition and transmission of FDV by P. saccharida are discussed. [ABSTRACT FROM AUTHOR]

The article is concerned with the isolation and identification of tomato ringspot virus from diseased Pentas lanceolata in South Australia. Virus was transmitted from P. lanceolata showing disease symptoms by mechanical inoculation using leaf extracts prepared in tap water or 0.1 M phosphate buffer, pH 7, to Nicotiana clevelandii A. Gray or cucumber (Cucumis sativus L.). Symptoms on N. clevelandii consisted of local necrotic ringspots on the inoculated leaves and systemic mosaic. On the cucumber seedlings, the virus produced chlorotic lesions on the inoculated cotyledons and a mosaic on systemically infected leaves.

A new virus, subterranean clover mottle virus (SCMoV) was found at several locations m Western Australia in Trifolium subterraneum L. (subterranean clover) with severe disease symptoms. Particles of the virus were shown to share many physical properties with members of the sobemovirus group. However, in addition to the single-stranded RNA of Mr about 1.5 ⊗ 106 which is characteristic of sobemoviruses, SCMoV particles also contained circular and linear viroid-like RNAs of two size classes, one about 400 and the other about 300 nucleotides long. At present it is not clear if the two types of viroid-like RNAs are components of the same SCMoV strain or of closely), related strains of the virus which are able to coinfect subterranean clover. SCMoV was shown to be serologically related to lucerne transient streak virus (LTSV). However, the relationship was remote and whereas most high-titred antisera to LTSV reacted with SCMoV particles, antisera to SCMoV failed to recognize those of LTSV. Neither SCMoV nor LTSV are serologically related to velvet tobacco mottle virus (VTMoV) or Solanum nodiflorum mottle virus (SNMV). However, particles of all four viruses have many physical and chemical properties in common, including RNA complements consisting of both virus-like and viroid-like RNAs. Because of their affinities and unique RNA complements, we suggest that SCMoV, LTSV, VTMoV and SNMV may warrant inclusion in a new taxonomic group. [ABSTRACT FROM AUTHOR]

We report a bit-rate transparent optical burst switching (OBS) router prototype using a fast 5 times 5 PLZT [(Pb,La)(Zr,Ti)O3 ] optical matrix switch. Dynamic switching in a two-wavelength, 2 times 2 OBS switch is demonstrated. Contention resolution using a tunable Mach-Zehnder interferometer wavelength converter for both 40- and 10-Gb/s bursts is demonstrated for the first time. Error-free operation was achieved for both bit rates under the same settings, as required in autonomous networks [ABSTRACT FROM PUBLISHER]