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Aims. The properties of transient horizontal magnetic fields(THMFs) in both plage and quiet Sun regions are obtained and compared.

Aims.We report the discovery of isolated, small-scale emerging magnetic fields in a plage region with the Solar Optical Telescope aboard Hinode.

Aims.Magnetic elements are thought to be described by flux tube models, and are well reproduced by MHD simulations. However, these simulations are only partially constrained by observations. We observationally investigate the relationship between G-band bright points and magnetic structures to clarify conditions, which make magnetic structures bright in G-band.

We measure the twist dependence of the reflected spectrum of a fiber Bragg grating (FBG) inscribed in a perfluorinated graded-index (PFGI) polymer optical fiber (POF). With increasing twist, the strain sensitivity decreases with a coefficient of -34.2 pm/%/turns/m, while the temperature sensitivity increases with a coefficient of 0.39 pm/°C/turns/m. At a twist of 150 turns/m, the temperature sensitivity is 3 times higher than that with no twist. The significance of the controllability of the strain/temperature coefficients is discussed. [ABSTRACT FROM AUTHOR]

A sounding-rocket program called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of 2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567 nm), aiming to detect the linear polarization signal produced by scattering processes and the Hanle effect for the first time. The polarimeter of CLASP consists of a rotating half-waveplate, a beam splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is used for these optical components, because MgF2 exhibits birefringent property and high transparency at ultraviolet wavelength. The development and comprehensive testing program of the optical components of the polarimeter is underway using the synchrotron beamline at the Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first objective is deriving the optical constants of MgF2 by the measurement of the reflectance and transmittance against oblique incident angles for the s-polarized and the p-polarized light. The ordinary refractive index and extinction coefficient along the ordinary and extraordinary axes are derived with a least-square fitting in such a way that the reflectance and transmittance satisfy the Kramers-Krönig relation. The reflection at the Brewster's Angle of MgF2 plate is confirmed to become a good polarization analyzer at Ly-alpha. The second objective is the retardation measurement of a zeroth-order waveplate made of MgF2. The retardation of a waveplate is determined by observing the modulation amplitude that comes out of a waveplate and a polarization analyzer. We tested a waveplate with the thickness difference of 14.57 um. The 14.57 um waveplate worked as a half-waveplate at 121.74 nm. We derived that a waveplate with the thickness difference of 15.71 um will work as a half-waveplate at Ly-alpha wavelength. We developed a prototype of CLASP polarimeter using the MgF2 half-waveplate and polarization analyzers, and succeeded in obtaining the modulation patterns that are consistent with the theoretical prediction. We confirm that the performance of the prototype is optimized for measuring linear polarization signal with the least effect of the crosstalk from the circular polarization.

A multi‐capillary nozzle emitter consisting of one metal plate with capillary nozzles and a ring type counter electrode was used as a multi‐electrospray atomizer. The number of capillary nozzles, flow rate of the liquid and the interval between the capillary nozzles were changed, and the droplet diameter and the voltage required for a steady cone‐jet mode were measured. For the multi‐capillary nozzle emitter, the interaction between the capillary nozzles is the important factor for obtaining fine droplets of uniform size. These fine droplets are obtained when there is only a small interaction between the capillary nozzles, and the equations obtained from the single capillary nozzle case are also applicable for the multi‐capillary nozzle emitter. When the number of capillary nozzles decreases (a situation which is not good for obtaining a large amount of droplets) or the interval between the capillary nozzles increases, the interaction between the capillary nozzles can be reduced. As the number of capillary nozzles increase, a higher voltage is required to obtain a fine droplet of uniform size.

Abstract: The purpose of this study was to assess the extent of genetic erosion of traditional upland germplasm in northern Thailand as a result of gene-flow from distinct strains carrying different genotypes. Even modern variety specific markers have not been developed, there is a comparative population in Laos. Thus, both populations were compared with various characters to evaluate gene-flow from modern variety to landraces. Glutinous and glabrous strains are predominated in Laos. However, such strains were drastically decreased in north–east Thailand. Gene diversity is higher in Thailand, compared to Laos at seven isozyme loci. This was a result of the higher frequencies of Indica strains and heterozygotes in Thailand. Plastid type was also determined by using an INDEL marker. Nearly half of Indica strains carried the Japonica plastid. Heterozygotes also tended to carry Japonica cytoplasm. Such nuclear–cytoplasm substituted strains and heterozygotes were probably generated by natural hybridization. Japonica strains tended to be a maternal donor rather than Indica ones. Or Indica strains would easily release pollens, which grow outside of upland fields.

In Bhutan, weedy rice (Oryza sativa L.) was grown together with cultivated rice on terraced paddy fields lower than 2620 m above sea level. Seeds of cultivars and weedy strains were collected at 22 collection sites located from 1000 to 2620 m above sea level. Cultivars with round seeds were frequently found in fields higher than 2250 m, and those with slender seeds in fields lower than 1630 m. All cultivars and weedy strains were divided into indica or japonica types by isozyme (multi-locus) and morpho-physiological (multicharacter) analyses. Japonica cultivars predominated in highland; Indica cultivars predominated in lowland. Plastid type was confirmed by the length polymorphism for the ORF100 region. The japonica cultivars carried non-deletion type ORF100. The indica cultivars carried deletion type ORF100. In contrast, weedy strains showed discrepancy in the combination of the nuclear and cytoplasm types. An intermediate type was found in weedy strains for isozyme genotypes. A recombinant type, which has indica genotypes for isozyme analysis with japonica cytoplasm, and vice versa, was frequently found in weedy strains. These findings suggested that weedy strains would be generated by natural hybridization between indica and japonica. Further, they might fail to recombine their prior genotypes sets for isozyme and cytoplasm. Morphophysiological characters did not show such a tendency. Morpho-physiological analysis of highland plants, in particular, showed indica cultivars and weedy strains with japonica cytoplasm. Hypervariable nuclear microsatellite analysis was then used to compare cultivars and weedy strains. Identical alleles were shared between indica and japonica, and also between cultivars and weedy strains. This suggested that there was gene-flow resulting from natural hybridization.

There are a large number of labeling methods for asparagine-type oligosaccharides with fluorogenic and chromophoric reagents. We have to choose the most appropriate labeling method based on the purposes such as mass spectrometry, high-performance liquid chromatography and capillary electrophoresis. Asparagine-type glycans are released from core proteins as N-glycosylamine at the initial step of the releasing reaction when glycoamidase F is employed as the enzyme. The N-glycosylamine-type oligosaccharides thus released by the enzyme are subjected to hydrolysis or mutarotation to form free-form oligosaccharides. In the detailed studies on the enzyme reaction, we found a condition in which the released N-glycosylamine-type oligosaccharides were exclusively present at least during the course of enzyme reaction, and developed a method for in situ derivatization of the glycosylamine-type oligosaccharides with 9-fluorenylmethyl chloroformate (Fmoc-Cl). The Fmoc labeled sialo- and asialo- (or high-mannose and hybrid) oligosaccharides were successfully analyzed on an amine-bonded polymer column and amide-silica column, respectively. The present method showed approximately 5 times higher sensitivities than that using 2-aminobenzoic acid (2-AA). The separation profile was similar to that observed using 2-AA method as examined by the analyses of carbohydrate chains derived from several glycoproteins including complex-type, high-mannose type and hybrid type of N-linked oligosaccharides. The labeled oligosaccharides were stable at least for several months when stored at −20 °C. Furthermore, it should be emphasized that the Fmoc-derivatized oligosaccharides could be easily recovered as free reducing oligosaccharides simply by incubation with morpholine in dimethylformamide solution. We obtained a pure triantennary oligosaccharide with 3 sialic acid residues as a free reducing form from fetuin in good yield after isolation of the corresponding Fmoc oligosaccharide followed by removing reaction of the Fmoc group. The proposed method will be useful for preparation of free oligosaccharides as standard samples at pmol−nmol scale from commercially available glycoproteins. Keywords: oligosaccharide mapping • glycoprotein • 9-fluorenylmethyl chloroformate (Fmoc-Cl)

We study interfacial properties of poly(n-hexyl isocyanate) (PHIC) films by surface pressure and interfacial pressure measurements and fluorescence microscopy as a function of the molecular weight of PHIC. The respective surface pressure−area isotherms exhibit a plateau indicative of multilayer formation, the plateau region is narrower, and the plateau surface pressure is higher with an increase in the PHIC molecular weight. PHIC having a contour length less than the persistence length behaves as a rodlike polymer at the air−water, and with an increase in the molecular weight the PHIC chains undergo chain entanglements to give smaller extrapolated area. Such a molecular weight dependence is in good agreement with the fluorescence images at the air−water interface. At the oil−water interface PHIC forms a monolayer and the interfacial pressure is constant below the area of 0.28 nm²/monomer unit of PHIC. The area is in good agreement with an area calculated by assuming that a rodlike cylindrical PHIC molecule lies on the water, irrespective of the molecular weight of PHIC.

We constructed a plasmid vector having a 1.4-kilobase pair insert of myosin light chain kinase (MLCK) cDNA in an antisense direction to express antisense mRNA. The construct was then transfected to SM3, a cell line from vascular smooth muscle cells, producing a few stable transfectants. The down-regulation of MLCK expression in the transfectants was confirmed by both Northern and Western blots. The control SM3 showed chemotaxic motility to platelet-derived growth factor-BB, which was supported by lamellipodia. However, the transfectants showed neither chemotaxic motility nor developed lamellipodia, indicating the essential role of MLCK in the motility. The specificity for the targeting was assessed by a few tests including the rescue experiment. Despite this importance of MLCK, platelet-derived growth factor-BB failed to induce MLC20 phosphorylation in not only the transfectants but also in SM3. The mode in which MLCK was involved in the development of membrane ruffling is discussed with special reference to the novel property of MLCK that stimulates the ATPase activity of smooth muscle myosin without phosphorylating its light chain (Ye, L.-H., Kishi, H., Nakamura, A., Okagaki, T., Tanaka, T., Oiwa, K., and Kohama, K. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 6666-6671).

An allele of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene (Md-ACS1), the transcript and translated product of which have been identified in ripening apples (Malus domestica), was isolated from a genomic library of the apple cultivar, Golden Delicious. The predicted coding region of this allele (ACS1-2) showed that seven nucleotide substitutions in the corresponding region of ACS1-1 resulted in just one amino acid transition. A 162-bp sequence characterized as a short interspersed repetitive element retrotransposon was inserted in the 5'-flanking region of ACS1-2 corresponding to position -781 in ACS1-1. The XhoI site located near the 3' end of the predicted coding region of ACS1-2 was absent from the reverse transcriptase-polymerase chain reaction product, revealing that exclusive transcription from ACS1-1 occurs during ripening of cv Golden Delicious fruit. DNA gel-blot and polymerase chain reaction analyses of genomic DNAs showed clearly that apple cultivars were either heterozygous for ACS1-1 and ACS1-2 or homozygous for each type. RNA gel-blot analysis of the ACS1-2 homozygous Fuji apple, which produces little ethylene and has a long storage life, demonstrated that the level of transcription from ACS1-2 during the ripening stage was very low.

Human fascin is an actin-bundling protein and is thought to play a role in the formation of microfilament bundles of microspikes and stress fibers in cultured cells. To explore the regulation of fascin-actin interaction, we have examined the effects of culture cell caldesmon and tropomyosin (TM) on actin binding activity of human fascin. Caldesmon alone or TM alone has little or no effect on the actin binding of fascin. However, caldesmon together with TM completely inhibits actin binding of human fascin. When calmodulin is added, the inhibition of fascin-actin interaction by caldesmon and TM becomes Ca2+ dependent because Ca2+/calmodulin blocks actin binding of caldesmon. Furthermore, as phosphorylation of caldesmon by cdc2 kinase inhibits actin binding of caldesmon, phosphorylation can also control actin binding of fascin in the presence of TM. As expected by the inhibition of fascin-actin binding, caldesmon coupled with TM also inhibits actin bundling activity of fascin. Whereas smooth muscle caldesmon alone or TM alone shows no effect, caldesmon together with TM completely inhibits actin bundling activity of fascin. This inhibition is again Ca2+ dependent when calmodulin is added to the system. These results suggest important roles for caldesmon and TM in the regulation of the function of human fascin.

A novel approach, "micro-optics", is proposed to realize coupling/branching in fiber-optic communications. The operation is based on the beam transformation in a graded index rod (beam undulation and beam size change), in association with reflection or refraction at a graded index rod facet. Small-size couplers/dividers have been devised by inserting a semitransparent mirror between the facets of two graded index rods with a length of a quarter of the undulation period. Their best features are small size, simple structure, low insertion loss, and wide application areas. An excess insertion loss as low as 0.5 dB has been realized in a 3-dB divider with SELFOC® rods. As further applications of them, wavelength division multiplexers/demultiplexers have been developed by replacing the semitransparent mirror with a dielectric interference filter. An insertion loss of as low as 1.2 dB and isolation of more than 20 dB for wavelength separation of 20 nm have been realized. Results are also shown on the other type of micro-optic couplers/dividers.

The structural polypeptides of the murine coronavirus DVIM (diarrhoea virus of infant mice) have been analysed in comparison with other strains MHV-2, MHV-3, MHV-4 (JHM) and MHV-S by SDS-PAGE. In the presence of 2-mercaptoethanol, three major glycopolypeptides, gp180, gp69, gp25 (as a group of similar species) and one major non-glycosylated polypeptide p58 were detected. The gp69 is a DVIM specific glycopolypeptide, in which the glycosidic moieties are linked to the core polypeptide through N-glycosidic bonds, and hence may be correlated with the short projections of the viral envelope. Further gp140, which appears in the absence of reducing agents, is apparently a dimer of gp69 held together by disulfide linkages. The gp25 family, on the other hand, consists of four polypeptides, two of which are not metabolically inhibited by tunicamycin suggesting that they are O-linked glycopolypeptides. DVIM seems to be serologically closely related to the MHV-S strain as shown by neutralization.

A novel protein with a molecular mass of 55 kDa, as determined by SDS-PAGE, was purified from plasmodia of Physarum polycephalum. The protein bound to actin filaments with a stoichiometry of 0.27 moles per mole of actin with an apparent dissociation constant of 4 × 10−8M. In the presence of ATP, the protein dissociated from actin filaments. Adenosine 5-(γ-thio)triphosphate and adenyl-5′-yl imidodiphosphate also abolished the actin-binding activity of the protein, but GTP did not. Because the cytoplasmic concentration of ATP oscillates in association with the shuttle streaming of the cytoplasm, it is possible that this protein might be involved in the actin-linked regulation of cytoplasmic streaming.

Summary Myosin in pollen tubes ofLilium longiflorum was partially purified, using an in vitro motility assay as a monitor. The main components in the partially purified preparation had molecular masses of 110, 120, and 140 kDa in SDS-PAGE. They became bound to actin filaments in an ATP-dependent manner. Among the components, only that of 120 kDa became bound to ATP and was concluded to be the heavy chain of pollen tube myosin.

Multiple isoforms of tropomyosin (TM) of rat cultured cells show differential effects on actin-severing activity of gelsolin. Flow birefringence measurements have revealed that tropomyosin isoforms with high Mrvalues (high MrTMs) partially protect actin filaments from fragmentation by gelsolin, while tropomyosins with low Mrvalues (low MrTMs) have no significant protection even when the actin filaments have been fully saturated with low MrTMs. We have also examined effect of nonmuscle caldesmon on the severing activity of gelsolin because 83-kDa nonmuscle caldesmon stimulates actin binding of rat cell TMs (Yamashiro-Matsumura, S., and Matsumura, F. (1988) J. Cell Biol.106, 1973–1983). While nonmuscle caldesmon alone or low MrTMs alone show no significant protection against fragmentation by gelsolin, the low MrTMs coupled with 83-kDa protein are able to protect actin filaments. Further, high MrTMs together with 83-kDa protein appear to block the severing activity completely. Electron microscopic analyses of length distribution of actin filaments have confirmed the results. The average length of control actin filaments is measured as 1.46 ± 1.0 µM, and gelsolin shortens the average length to 0.084 ± 0.039 µM. Similar short average lengths are obtained when gelsolin severs actin complexed with low MrTMs (0.080 ± 0.045 µM) or with nonmuscle caldesmon (0.11 ± 0.072 µM) while longer average length (0.22 ± 0.18 µM) is measured in the presence of high MrTMs. The simultaneous addition of nonmuscle caldesmon makes the average length considerably longer, i.e.0.61 ± 0.37 µMin the presence of low MrTMs and 1.57 ± 0.97 µMin the presence of high MrTMs. Furthermore, the actin binding of gelsolin is strongly inhibited by co-addition of high MrTMs and nonmuscle caldesmon. These results suggest that TM and gelsolin share the same binding site on actin molecules and that the differences in the actin affinities between TMs are related to their abilities of protection against gelsolin.

Previous results from our laboratory have shown that 1) cultured rat cells contain two classes of tropomyosin (TM), one (high MrTMs) with higher Mrvalues and greater affinity for actin than the other (low MrTMs); 2) presaturation of F-actin with high MrTMs, but not with low MrTMs, inhibits both actin-severing and actin binding activities of gelsolin; and 3) nonmuscle caldesmon not only enhances the inhibitory effects of high MrTMs but also makes low MrTMs capable of inhibiting the severing activity of gelsolin (Ishikawa, R., Yamashiro, S., and Matsumura, F. (1989) J. Biol. Chem. 264, 7490-7497). These results suggest that gelsolin has much lower affinity for F-actin-TM-caldesmon complexes than for pure F-actin. We have therefore examined whether addition of TM and/or caldesmon to gelsolin-severed actin filaments can make gelsolin dissociate from barbed ends of actin filaments, resulting in annealing of short actin filaments into long ones. Flow birefringence and electron microscopic studies have suggested that high MrTMs slowly and partially anneal gelsolin-severed actin fragments in 3 h, whereas low MrTMs have no effects. Nonmuscle caldesmon greatly potentiates the effects of high MrTMs and accelerates the process to 20 min, whereas nonmuscle caldesmon alone shows no effects. Furthermore, nonmuscle caldesmon makes low Mr TMs capable of reversing gelsolin-severing action. Actin binding assay has shown that gelsolin (or a gelsolin-actin complex) is dissociated from these annealed actin filaments. Smooth muscle TM and smooth muscle caldesmon also appear to anneal gelsolin-severed actin fragments as do high MrTMs and nonmuscle caldesmon. Calmodulin decreases the potentiation effects of caldesmon as calmodulin inhibits actin binding of caldesmon. These results suggest that tropomyosin and caldesmon may regulate both capping and severing activities of gelsolin.

DNA amplification fingerprinting using arbitrary primer(s) was applied to the identification of Malus species. Highly variable DNA fragment patterns were clearly detected by polyacrylamide gel electrophoresis of the amplified extension products, although three sports of Delicious exhibited the same fingerprint as the original cultivar. The fingerprinting of two triploid apple cultivars suggested that the parent contributing the 2n gamete was the female. We applied this fingerprinting to paternity analysis of an apple cultivar of which the pollen parent was unknown. By using 5 arbitrary primers and RFLP analysis of the amplified products, one cultivar was singled out for paternity among six putative candidates.

Nitrogen adsorption isotherms for fluorinated activated carbon fiber (F-ACF) and fluorinated carbon black (F-CB) were measured at 77 K. Surface structures of F-ACF and F-CB were examined by as-plot analysis using the adsorption data on the nonporous carbon black (CB) and F-CB. The surface energy of F-ACF was lower than that of ACF. The micropore structure of ACF was preserved even after fluorination, although the limiting adsorption amount and the micropore width decreased with fluorination.

Somatic hybrid cell lines were constructed by the fusion of protoplasts isolated from cell suspensions of Zea mays L. (maize, 2n = 20) and Triticum sect, trititrigia MacKey (trititrigia, 2n = 35), a perennial hybrid of T. durum Desf. and Elytrigia intermedium (Host) Nevski. Iodoacetamide-inactivated protoplasts of maize were fused with trititrigia protoplasts, which were sensitive to the PEG/DMSO fusion treatment at high pH and high calcium. Based on physiological complementation, approximately 0.002% of the total protoplasts cultured following fusion treatment developed into cell colonies, and 79 lines of them, almost a half, were singled out and subcultured. Among the subcultured lines three were, in comparison with the parents, identified as somatic hybrids by their coupled XbaI restriction patterns of total DNAs probed with the ribosomal DNA of rice. Southern analysis of the digested total DNAs with a mitochondrial gene, atpA., from pea, or a chloroplast gene, trnK, from rice, revealed that all the hybrids carried only the organellar DNAs of trititrigia, which excluded the possibilities of a chimeric callus or any DNA contamination. Cytogenetically, one hybrid was mixoploid with a 2n of 46–67 in which chromosomal endoreduplication, characterized by the appearance of diplochromosomes, was occasionally observed. Its hybridity was reconfirmed by the fact that it bore the satellite chromosomes of both maize and trititrigia, which were distinguishable from each other by size. In contrast, the other two hybrids were aneuploids. The potential of gene transfer between Zea and Triticum species was thus conclusively established.

Lotus comiculatus L. is a widely cultivated, outbreeding, leguminous forage crop. Seventy-one plants, most of which were tetraploid, were regenerated from calli derived from a single protoplast. Their morphological and agronomic traits were evaluated and compared with those of the seed-produced population. The variances of most of the traits in the protoplast-derived (protoclonal) population were smaller than those of the seed-produced population. Mean values of all the traits of the protoclonal population shifted significantly towards lower values. However, new phenotypic variants with higher values than those of the plant initially used for protoplast isolation were also observed. Plants with less hydrocyanic acid (which has a toxic effect on cattle) than the initial plant were obtained in the protoclones. Generally, the pollen fertility of protoclones was significantly low compared with the seed-produced plants. This seems to be partly due to the occurrence of abnormalities in chromosome structure during protoplast and/or callus culture, as suggested by the formation of univalents, lagging, and fragment chromosomes and bridges at metaphase I and anaphase I and II of the regenerants. The changes in chromosome structure, however, did not induce any malformed morphologies.

With the aim of minimizing dioxin formation in industrial‐scale plants, incinerator facilities of the twin interchanging fluidized‐bed type were studied for the major factors influencing the dioxin level. A statistical model was derived based on multiple regression analysis of experimental data. It was found that the toxic equivalency level of dioxins is strongly positively correlated with fly ash copper and moderately with flue gas O2content, and strongly negatively correlated with fly ash chlorine and weakly with carbon content.

A simple and practical polarisation-independent directional coupler switch has been developed. The switch has an 18 V drive voltage, a below -17dB crosstalk and a 2.8 dB insertion loss between single-mode fibres at any incident polarisations with 1.3 μm wavelength.

A ten-port planar star coupler has been developed, utilising multimode waveguides easily formed in a glass substrate by evaporated silver ion diffusion. The waveguides have circular cross-sections with graded-index profile, which matches well to graded-index multimode fibres. Insertion loss of 6 dB and the loss variation of 0.8 dB were attaied.

Practical 4-port and 8-port kaleidoscope micro-optic star couplers for optical-fibre data links have been developed, with the advantages of low insertion losses well balanced among the ports, high reliability, easy fabrication and small size. This coupler utilises image formation by multireflection at the side planes of a cross-sectionally wedge-shaped small rod lens, and is therefore called a kaleidoscope micro-optic star coupler.

The adsorption isotherms of H2O, CH3OH, and C2H5OH on fluorinated activated carbon fiber (F-ACF) and pristine ACF were measured. H2O was not adsorbed by F-ACF, while the H2O adsorption isotherm of ACF was of type V. The adsorption isotherms of CH3OH and C2H5OH by ACF were of type I. On the other hand, their isotherms by F-ACF were of type V. In particular, the uptake in low pressure regions was markedly decreased by fluorination.

An integrated optical frequency modulator has been developed for a fibre-optic gyroscope using the frequency modulation method. A low insertion loss of 14 dB, which enables a 10−6 rad/s sensitivity, was obtained by realising low coupling loss between the single-mode fibre and titanium-diffused LiNbO3 slab waveguide.

A low-insertion-loss automatic optical fibre polarisation control system with low driving voltage and low monitoring power has achieved stabilisation of the receiver sensitivity within the fluctuation range of less than 0.4 dB in an optical FSK heterodyne 280 Mbit/s, 141 km transmission experiment.

Marked low-loss coupling between a laser diode and a single-mode fibre has been realised, utilising a planoconvex, high-numerical-aperture graded-index rod lens with greatly improved small wavefront aberration.

A 20-channel micro-optic grating demultiplexer with a single-mode input fibre has been developed for 1.1–1.6 μm band using a newly developed graded-index (Selfoc) rod lens with a small focusing parameter and an Si-etched reflection grating. Insertion losses were 1.9 to 3.5 dB. Isolation between adjacent channels was less than −20 dB.

The effect of laser-diode frequency chirping on harmonic distortions in multimode fibre analogue transmission with direct intensity modulation was clarified experimentally with results in good agreement with the theory. The results show that the harmonic distortion can be greatly reduced by the reduction of the frequency chirping which accompanies diode-laser intensity modulation.