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Specimens should be examined as much as possible to obtain a precise estimate of the proportion of resistance alleles in agricultural fields. Monitoring traps that use semiochemicals on sticky sheets are helpful in this regard. However, insects captured by such traps are ordinarily left in the field until collection. Owing to DNA degradation, the amount of DNA greatly varies among insects, causing serious problems in obtaining maximum likelihood estimates and confidence intervals of the proportion of the resistance alleles. We propose a statistical procedure that can circumvent this degradation issue. R scripts for the calculation are provided for readers. We also propose the utilization of a Sanger sequencer. We demonstrate these procedures using field samples of diamide-resistant strains of the diamondback moth

Long-term pest insect monitoring in agriculture and forestry has advanced population ecology. However, the discontinuation of research materials such as pheromone lure products jeopardizes data collection continuity, which constrains the utilization of the industrial datasets in ecology. Three pheromone lures against the smaller tea tortrix moth Adoxophyes honmai Yasuda (Lepidoptera; Tortricidae) were available but one was recently discontinued. Hence, a statistical method is required to convert data among records of moths captured with different lures. We developed several generalized additive mixed models (GAMM) separating temporal fluctuation in the background male density during trapping and attenuation of lure attractiveness due to aging or air exposure after settlement. We collected multisite trap data over four moth generations. The lures in each of these were unsealed at different times before trap settlement. We used cross-validation to select the model with the best generalization performance. The preferred GAMM had nonlinear density fluctuation terms and lure attractiveness decreased exponentially after unsealing. The attenuation rates varied among lures. A light trap dataset near the pheromone traps was a candidate for a male density predictor. Nevertheless, there was only a weak correlation between trap yields, suggesting the difficulty of data conversion between the traps differing in attraction mechanisms.

High-levels of etoxazole resistance have not yet been frequently reported in Panonychus citri. Although a highly resistant strain was discovered in 2014, etoxazole resistance has not become a significant problem in areas of citrus production in Japan. A target site mutation in chitin synthase 1 (CHS1), I1017F, is a major etoxazole-resistance factor in Tetranychus urticae. To investigate the mechanisms of etoxazole resistance and the dispersal of resistance genes, we analyzed target-site mutations in a highly resistant strain and their geographical distribution in Japan.High-level etoxazole resistance was completely recessive. The I1017F mutation was detected in CHS1 of the highly resistant strain, and its frequency was correlated with the hatchability of eggs treated with etoxazole. Sequencing and variant frequency analyses of local populations by quantitative polymerase chain reaction revealed that I1017F is restricted to the Ariake Sea area of Kyushu Island. Although a new nonsynonymous substitution, S1016L, accompanied by I1017F was found in CHS1 of the highly resistant strain, CRISPR/Cas9 engineering of flies showed that S1016L had no effect on the etoxazole resistance conferred by I1017F.I1017F is a major target site mutation that confers high-level etoxazole resistance on P. citri. Dispersion of I1017F possibly was suppressed as a result of the completely recessive inheritance of resistance together with low gene flow between local populations. © 2022 Society of Chemical Industry.

Insecticide resistance management has been key for crop protection for over 70 years and is increasingly important because the development of new active ingredients has decreased in recent years. By monitoring the development of resistance in a timely manner, we can effectively prolong insecticide efficacy. Genomic-based diagnosis can reliably predict resistance development if information on resistant mutations against major pesticides is available. Here, we developed a feasibility trial of genomics-based diagnosis of insecticide resistance in diamondback moth (Plutella xylostella) populations in Nagano Prefecture, Japan. Amplicon sequencing analyses using a next-generation sequencer (Illumina MiSeq) for major insecticides, including diamides, pyrethroids, Bacillus thuringiensis (Bt) toxin (Cry1Ac), organophosphates, and spinosyns, were conducted.Mutations related to the resistance of pyrethroids, organophosphates, and diamides (flubendiamide and chlorantraniliprole) prevailed, while those of a diamide (cyantraniliprole), Bt (Cry1Ac), and spinosyns were scanty, suggesting that they are still effective. The results of the genomics-based diagnosis were generally concordant with the results of bioassays. Resistance development tendencies were generally uniform across Nagano.An insecticide-resistance management campaign can be conducted in Nagano Prefecture with a quick genomic-based diagnosis in early spring while bioassay is the only option for monitoring resistances whose mutations are unavailable. Our study is the first step in the future management of insecticide resistance in all significant pests. © 2022 Society of Chemical Industry.

PCR techniques, both quantitative (qPCR) and nonquantitative, have been used to estimate the frequency of a specific allele in a population. However, the labour required to sample numerous individuals and subsequently handle each sample renders the quantification of rare mutations (e.g., pesticide resistance gene mutations at the early stages of resistance development) challenging. Meanwhile, pooling DNA from multiple individuals as a “bulk sample” combined with qPCR may reduce handling costs. The qPCR output for a bulk sample, however, contains uncertainty owing to variations in DNA yields from each individual, in addition to measurement errors. In this study, we have developed a statistical model to estimate the frequency of the specific allele and its confidence interval when the sample allele frequencies are obtained in the form of ΔΔCq in the qPCR analyses on multiple bulk samples collected from a population. We assumed a gamma distribution as the individual DNA yield and developed an R package for parameter estimation, which was verified using real DNA samples from acaricide-resistant spider mites, as well as a numerical simulation. Our model resulted in unbiased point estimates of the allele frequency compared with simple averaging of the ΔΔCq values. The confidence intervals suggest that dividing the bulk samples into more parts will improve precision if the total number of individuals is equal; however, if the cost of PCR analysis is higher than that of sampling, increasing the total number and pooling them into a few bulk samples may also yield comparable precision., 野外の生物集団の遺伝子頻度を効率よく推定する統計モデルを開発 --複数個体を一括して抽出したサンプルにおけるDNA量の個体差に対処する--. 京都大学プレスリリース. 2022-10-12.

In this paper, we evaluated the doping density and spatial distribution of Ce3+ ions in a LiCaAlF6 single crystal. We observed the heterogeneity of Ce3+-doped LiCaAlF6 using Multi-Photon Luminescence Measurement. Further, we employed laser ablation inductively coupled plasma mass spectrometry to perform elementary analysis. We measured the concentration and distribution of Ce, Li, Ca, and Al. The luminescence intensity increased in proportion to the Ce concentration. Therefore, our evaluation method, which measures the multi-photon luminescence intensity, can possibly be employed to analyze the concentration and distribution of a low amount of elements due to luminescence. Additionally, we can evaluate the luminescence materials nondestructively and three-dimensionally by this measurement. This method could be a dominant tool for evaluation of luminescent materials compared with the conventional methods.

The evolution of resistance against pesticides is an important problem of modern agriculture. The high-dose/refuge strategy, which divides the landscape into treated and nontreated (refuge) patches, has proven effective at delaying resistance evolution. However, theoretical understanding is still incomplete, especially for combinations of limited dispersal and partially recessive resistance. We reformulate a two-patch model based on the Comins model and derive a simple quadratic approximation to analyze the effects of limited dispersal, refuge size, and dominance for high efficacy treatments on the rate of evolution. When a small but substantial number of heterozygotes can survive in the treated patch, a larger refuge always reduces the rate of resistance evolution. However, when dominance is small enough, the evolutionary dynamics in the refuge population, which is indirectly driven by migrants from the treated patch, mainly describes the resistance evolution in the landscape. In this case, for small refuges, increasing the refuge size will increase the rate of resistance evolution. Our analysis distils major driving forces from the model, and can provide a framework for understanding directional selection in source-sink environments.

Silicon and GaAs are typical materials used in terahertz components because of their high transparency and low dispersion, but their high refractive indices will cause about 30% reflection loss in power. Fabricating gradient index photonic structures (also known as moth-eye structure) on the surface of components have been examined suitable especially to terahertz system. In order to achieve high performance on anti-reflection in these structures, the gradient profile of refractive index, this is, the shape of tapers is important as well as high aspect ratio (= depth/pitch in tapers). We theoretically calculated anti-reflection characteristics of tapered structures with different refractive index taper profiles of Klopfenstein, linear and exponential, and the results showed that the Klopfenstein taper profile has the best performance on anti-reflection at the THz frequencies. Moreover, Femtosecond laser is reported as a strong method to perform microfabrication on Silicon substrate. However, if femtosecond pulses are continuously irradiated to the same point, the ablated material will absorb the incident pulse again, and reattach to the original point, which hindered the obtaining of high aspect ratio and shape control of the taper. By increasing the scan speed of laser beam, we decreased the pulse number continuously irradiated in unit time to reduce the thermal influence, and obtain a higher aspect ratio and smooth surface of the tapers. We employed femtosecond laser processing to fabricate anti-reflective structures formed by periodic tapers with different pitches. We also evaluated their anti-reflection characteristics experimentally and theoretically at terahertz frequencies (0.1 THz ~ 2 THz). The experimental results showed that the Fresnel reflection is almost decreased to zero at a wider frequency band, and the measured frequency dependence of reflection in the grating structures is good agreement with theoretical ones. These results showed that the laser processing is very useful to fabricate anti-reflection structures with precise dimensions.

Because optical fiber-based optical systems are generally robust against external interference, they can be used as reliable systems in industrial applications in various fields. This paper describes fiber lasers generating femtosecond pulses that use optical fibers as gain media and optical paths. Additionally, the nondestructive paint multilayer thickness measurement of automotive parts using terahertz waves generated and detected by femtosecond fiber laser systems was conducted.

Anti-reflective structures formed by periodic grooves, have been fabricated by femtosecond laser processing. Molten materials due to thermal influence during processing hindered the obtaining of high aspect ratio (=depth/pitch in tapers) and shape control of the taper. These are important to improve the anti-reflective characteristics of these structures. By increasing the scan speed of laser beam, we decreased the effective pulse number to reduce the thermal influence. By controlling the pitch of these tapers, we fabricated tapered structures with different anti-reflective band.

We fabricated nanostructures on molybdenum with a femtosecond laser, and pores and spikes that are smaller than LIPSS were observed. Additionally, we controlled the wettability with micro and nanostructures as well as just nanostructures.

Carbide nanoparticles are used in various applications. However, conventional fabrication methods are tend to be complicated and several steps are needed until fabrication. In this work, we report a simple method to fabricate carbide nanoparticles by femtosecond laser ablation in hexane.

Patterning oxidation was performed by irradiating femtosecond laser pulses to surface of oxygen-free copper substrate. Conglomerations less than 1 μm were observed on irradiated are by SEM. Expansion (about 400 nm) and discoloration of irradiated area were observed by CLSM. By Raman spectroscopy, peaks attributed to copper oxide (CU20: 219 cm-1, CuO: 298 cm-1) were observed. Results of EDX show that oxygen is relatively uniformly distributed on the sample treated at 25 mW, comparing with samples treat at 10 mW and 50 mW. About the results of XRD, peaks attributed to Cu (2 0 0) and Cu (2 2 0) decreased, and the peak attributed to Cu20 (1 1 1) and CuO (−1 1 3) were observed.

Although theoretical studies have shown that the mixture strategy, which uses multiple toxins simultaneously, can effectively delay the evolution of insecticide resistance, whether it is the optimal management strategy under different insect life histories and insecticide types remains unknown. To test the robustness of this management strategy over different life histories, we developed a series of simulation models that cover almost all the diploid insect types and have the same basic structure describing pest population dynamics and resistance evolution with discrete time steps. For each of two insecticidal toxins, independent one‐locus two‐allele autosomal inheritance of resistance was assumed. The simulations demonstrated the optimality of the mixture strategy either when insecticide efficacy was incomplete or when some part of the population disperses between patches before mating. The rotation strategy, which uses one insecticide on one pest generation and a different one on the next, did not differ from sequential usage in the time to resistance, except when dominance was low. It was the optimal strategy when insecticide efficacy was high and premating selection and dispersal occur.

Reproductive success and population growth of an herbivorous mite are limited by activities of phytoseiid predators. However, occurrences on upper versus lower leaf surfaces are sometimes mismatched between these prey and predators. The mismatch potentially mitigates predation risk for the prey species. We assessed factors that affect mite distributions on leaf surfaces, testing whether the presence of the phytoseiid mite Phytoseius nipponicus alters the leaf-surface distribution and reproductive success of the herbivorous false spider mite Brevipalpus obovatus. The host plant was Viburnum erosum var. punctatum (Adoxaceae). Leaves were set in natural (TRUE) and reversed (upside down; INVERTED) orientations using experimental devices. Both surfaces were accessible to mites. We detected lower and abaxial leaf-surface preferences in P. nipponicus. In contrast, upper and adaxial surfaces were preferred by B. obovatus. Thus, prey and predatory mites accumulated on different sides of leaves. Presence of the predator also indirectly decreased egg production in B. obovatus. Brevipalpus obovatus females actively avoided leaf surfaces with elevated predator numbers; these females shifted their distributions and changed oviposition sites to leaf surfaces with fewer predators. In consequence, B. obovatus eggs on the upper sides of leaves were less frequently preyed upon than were those on lower sides. We suggest that upper leaf-surface exploitation in this particular herbivorous mite species mitigates predation risk from phytoseiid mites, which prefer lower leaf surfaces.

Solar ultraviolet-B (UVB) radiation has deleterious effects on plant-dwelling mites. We assessed the biological effects of UVB radiation on the eggs of the twospotted spider mite, Tetranychus urticae Koch, under both near ambient (UV+) and UV-attenuated (UV−) conditions from spring to autumn and compared them to the effects of temperature and humidity. The ambient daily UVB irradiance increased from January to August and then decreased rapidly until December, whereas egg hatchability under UV+ was lowest in April (10.7%) and increased almost linearly until October (74.9–92.3%). In contrast, hatchability under UV− was consistently high (96.2–99.8%) through all seasons. For UV+, the stepwise multiple linear regression analysis supported the negative correlation of hatchability with cumulative UVB irradiance during egg periods (cumulative dose), but did not support that with the mean daily UVB irradiance (dose rate), suggesting that UVB-induced mortality in T. urticae eggs is cumulative dose dependent rather than dose rate dependent. The high mortality in April may have reflected the slower development caused by the relatively lower temperature and higher UVB radiation, increasing the cumulative dose, while the low mortality in October may have reflected the faster development caused by the relatively higher temperature and lower UVB radiation, decreasing the cumulative dose.

We demonstrate high baud-rate DQPSK modulation with full-ETDM technique using a novel high-speed optical IQ modulator consisting of a ridge-type optical waveguide structure on a thin LiNbO3 substrate. Our fabrication technique achieves a drastic extension of the modulator's bandwidth and a reduction of half-wave voltage. Demonstration of 90-Gbaud NRZ-DP-DQPSK signal generation with the modulator successfully achieved a bit rate of 360-Gb/s under full-ETDM configuration.

We propose a polarization-multiplexing QPSK modulator for synthesis of a 16 QAM signal. The generation mechanism of 16 QAM is based on an electro-optic vector digital-to-analog converter, which can generate optical multilevel signals from binary electric data sequences. A quad-parallel Mach-Zehnder modulator (QPMZM) used in our previous research requires precise control of electric signals or fabrication of a variable optical attenuator, which significantly raises the degree of difficulty to control electric signals or device fabrication. To overcome this difficulty, we developed the polarization-multiplexing QPSK modulator, which improved the method of superposition of QPSK signals. In the polarization-multiplexing QPSK modulator, two QPSK signals are output with orthogonal polarization and superposed through a polarizer. The amplitude ratio between the two QPSK signals can be precisely controlled by rotating the polarizer to arrange the 16 symbols equally. Generation of 16 QAM with 40Gb/s and a bit error rate of 5.69×10-5 was successfully demonstrated using the polarization-multiplexing QPSK modulator. This modulator has simpler configuration than the previous one, utilized a dual-polarization MZM, alleviating complicated control of electric signals.

Fine leaf structures, such as leaf domatia or trichomes, are considered to affect the population abundance and diversity of foliar mites on forest trees and shrubs; however, the effect of such structures on seasonal fluctuations in foliar mite populations in forest ecosystems remains unknown. The authors conducted a 2-year survey on the outskirts of Kyoto on the mite assemblage found on Viburnum erosum var. punctatum (VEP), a deciduous shrub bearing domatia and stellate hairs, and on its seasonal fluctuations. A census was also conducted on the acarofauna on 14 sympatric tree or shrub species; these communities were then compared with those found on VEP. On VEP, fungivorous mites, Winter-schmidtiidae and Tydeoidea, showed continuous occurrence from late March to November, and phytoseiid mites were recorded from May to November. Eriophyioid mites were only found in spring and autumn. Total mite density was significantly higher on plant species with fine structures, and the acarofauna on such plants showed high similarity among seasons. Our data suggest that leaf-surface structures play important roles in structuring foliar mite communities throughout the seasons.

We have fabricated Eu2+:LiCaAlF6 (Eu:LiCAF) nanoparticles via a dry pulsed laser ablation process using femtosecond laser pulses. The particle size was controlled by adjusting the laser fluence. The crystallographic orientation and chemical composition were preserved in all particles. The typical luminescence peak of Eu:LiCAF crystals at approximately 370 nm was observed in both the PL and X-ray induced luminescence (XL) spectra. The temporal PL profiles of all deposited particles exhibited fast-decay components in addition to the slow-decay components observed in the profile of the bulk crystal. Smaller particles had shorter decay times than larger particles. The fast-decay component of particles with a mean diameter of less than 0.36 μm (∼40 ns) was at least one order of magnitude shorter than the decay time of the bulk crystal (∼1700 ns). Even in the temporal XL profile, all deposited particles showed shorter decay times than the bulk decay time. We attribute these fast-decay components to defects on t...

We demonstrate 75-km single-mode fiber transmission of a 40-Gb/s optical 16-level quadrature amplitude modulation (16QAM) signal generated by a quad-parallel Mach-Zehnder optical modulator (QPMZM), where four Mach-Zehnder structures are embedded in parallel monolithically on a lithium niobate substrate. Owing to the optical 16QAM signal generation method based on the coherent superposition in the QPMZM and improved coherent receiver utilizing digital filters, improvement of receiver sensitivity has been achieved as well. The experimentally obtained receiver sensitivity for near the forward-error correction limit and power penalty due to transmission are experimentally evaluated as 16.3 dB and about 2-3 dB, respectively.

The eggs of the herbivorous false spider mite Brevipalpus obovatus Donnadieu have a longer incubation period than those of spider mites and are not protected by webs. Brevipalpus obovatus often lays its eggs in the gaps among the hairs on host leaves. We examined the effects of stellate hairs of Viburnum erosum var. punctatum (VEP) leaves on the survival of B. obovatus eggs. Adult B. obovatus and Phytoseius nipponicus Ehara, a generalist predator, were introduced to VEP leaf disks; each B. obovatus egg was inspected daily until hatching. More eggs (63 vs. 42 %) survived on the abaxial surfaces of VEP leaves, where the stellate hairs are more complicated, than on the adaxial surfaces. Predation hazard decreased rapidly with increasing egg age and a substantial portion of the eggs hatched. Phytoseius nipponicus preyed on eggs regardless of egg age when mixed-age eggs were provided. Manipulative experiments with bent stellate hairs showed that the normal hairs reduced the predation risk of B. obovatus eggs by P. nipponicus. Therefore, the predation hazard was considered to decrease since the stellate hairs hindered the search for B. obovatus eggs by the phytoseiid mite.

Plant-dwelling mites are potentially exposed to solar ultraviolet-B (UVB) radiation that causes deleterious and often lethal effects, leading most mites to inhabit the lower (underside) leaf surfaces. However, in species of spider mite belonging to the Genus Panonychus, a substantial portion of individuals occur on upper leaf surfaces. We investigated whether the upper leaf surfaces of citrus trees are favorable for P. citri, and to what extent they are tolerant to UVB radiation. If eggs are not adequately protected from UVB damage, females may avoid ovipositing on the upper surfaces of sunny leaves. To test this, we conducted laboratory experiments using a UVB lamp, and semioutdoor manipulative experiments. As a result, P. citri eggs are tolerant to UVB. Field studies revealed that the ratio of eggs and adult females on upper leaf surfaces were larger for shaded than for sunny leaves. However, 64-89% of eggs hatched successfully even on sunny upper leaf surfaces. Nutritional evaluation revealed that whether on sunny or shaded leaves, in fecundity and juvenile development P. citri reaped the fitness benefits of upper leaf surfaces. Consequently, P. citri is tolerant to UVB damage, and inhabiting the upper surfaces of shaded leaves is advantageous to this mite.

We demonstrate generation of 80 Gb/s polarization division multiplexed (PDM) 16QAM signals. 16QAM signals were generated by a polarization-multiplexing QPSK modulator with polarization angular superposition, and PDM-16QAM signals were transmitted over 20 km single-mode fibers.

The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west-central Japan. We compared adaxial-abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat.

We propose a polarization-multiplexing QPSK modulator for 16 QAM generation. 16 QAM is synthesized from two QPSK signals with orthogonal polarization by a polarizer. Generation of 40 Gb/s 16 QAM with the BER of 8.13×10−6 was demonstrated.

We demonstrated 95-Gb/s NRZ-DPSK modulation by using high-speed modulator and full-ETDM technique. The BER performance under a back-to-back condition is achieved to be 7.1 × 10−4 at 95 Gb/s.

We experimentally demonstrate an optical 16-QAM transmitter using a monolithically integrated quad-Mach-Zehnder in-phase/quadrature (QMZ-IQ) modulator with binary driving electronics.

We propose and fabricate a monolithically integrated quad Mach-Zehnder in-phase quadrature (QMZ-IQ) modulator, where four sub-Mach-Zehnder (sub-MZ) modulators are arranged in an IQ super-structure and integrated in a single LINbO3 substrate. By feeding different electronics and operating at different bias conditions, it has been deployed to synthesize several different advanced optical modulation formats, like 20- and 80-Gb/s minimum phase-shift keying (MSK), 40-Gb/s quadrature phase-shift keying (QPSK), and 40-Gb/s quadrature amplitude modulation (QAM).

The modulation of a 166-Gb/s PDM-NRZ-DPSK signal is demonstrated using a thin-LiNbO 3 -substrate modulator. The use of a 0.1-mm-thick substrate and a ridge-type waveguide improves the optical response and brings about a reduction in Vπ.

160-Gb/s NRZ-DQPSK modulation is demonstrated with a thin-LiNbO 3 -substrate modulator. Using this substrate with a ridge-type waveguide structure can help realize an extension of a bandwidth and a decrease of a half-wave voltage of the modulator.

We experimentally demonstrate a 16-QAM transmitter using a monolithically-integrated quad Mach-Zehnder in-phase/quadrature (QMZ-IQ) modulator with binary driving electronics.

In this paper, we demonstrate a new sensor for simultaneous measurement of temperature and strain using a fiber grating written in a PANDA fiber. Because this grating sensor has a probe size as small as few millimeters, it is promising as a local sensing device for various applications.

We conducted point censuses in Yakushima island to estimate the density of Japanese macaque (Macaca fuscata yakui) males ranging alone, focusing on its vegetational, seasonal, and regional variation. In highland areas, the detection frequency of males ranging alone did not differ among different types of vegetation, despite the latter's effect on overall population density. The detection frequency of males ranging alone in the mating season was a third of that in the non-mating season. In the mating season, males exhibit strong cohesiveness with a group, probably in search of resident estrous females. Outside of the mating season, we detected 25% fewer males ranging alone in lowland areas, which have high population densities and strong inter-group competition, than in highland areas. The absolute density of males ranging alone was estimated to be 1.2–5.7 individuals/km2. Meanwhile, the group and population densities were 1.25/km2 and 19.3/km2, respectively. A considerable number of males theref...

A monolithically-integrated quad-parallel Mach-Zehnder optical modulator has been fabricated. 3 and 6 dB electro-optical bandwidths of Mach-Zehnder structures embedded in the modulator were evaluated as 22 and 36 GHz, respectively. By using the monolithic optical modulator, a 10 Gbaud 16-level quadrature amplitude modulation (QAM) signal was successfully obtained.