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We report novel high-bandwidth InP-based Mach–Zehnder modulator and in-phase/quadrature (IQ) modulators that we realized by combining an n-i-p-n heterostructure and a capacitively loaded traveling wave electrode. The extremely low electrical and optical loss structure enhances the 3-dB electro-optic bandwidth of over 67 GHz without degrading other properties such as driving voltage and optical loss. The modulator also exhibits a static extinction ratio of over 24 dB with a V π of less than 1.5 V for the entire C-band. Furthermore, we demonstrate the first 120-Gbaud rate IQ modulation without optical pre equalization, and 100-Gb/s non-return-to-zero on-off keying modulation with a dynamic extinction ratio of over 10 dB.

We developed ultra-low power ( 44 GHz) coherent modulator modules with a CMOS driver IC and an InP modulator. Dual polarization 64-Gbaud 16-QAM modulation was successfully demonstrated.

We present recently developed ultra-high bandwidth and low V„ InP-based in-phase/quadrature (IQ) modulators that we realized by combining an n-i-p-n heterostructure and a capacitively loaded traveling wave electrode. The extremely low electrical and optical loss structure enhances the 3-dB electro-optic bandwidth of over 67 GHz without degrading other properties such as driving voltage and optical loss. The IQ modulator itself exhibits up to 120-Gbaud rate IQ modulations without optical pre equalization. Furthermore, we examined a low-power dissipation IQ modulator co-assembled with a 495-mW/2ch CMOS differential driver IC, and successfully demonstrated a 64-Gbaud/16QAM operation.

100-Gb/s-class high-speed transmission technologies are essential to realize future 100 G Ethernet transmission over wide area networks. Optical OFDM (Orthogonal Frequency Division Multiplexing) is promising for high-speed transmission because of its narrow bandwidth and superior tolerance to chromatic dispersion and polarization mode dispersion. In this paper, we show numerically that the nonlinear tolerance of optical OFDM increases as the subcarriers is decreased and describe novel electro-optic subcarrier multiplexing scheme to generate an over 100 Gb/s high speed optical OFDM signal with a small number of subcarriers. We successfully generate a 100 G-class optical OFDM signal and demonstrate transmission over 80-km of ITU-T G.652 single-mode fiber without dispersion compensation.

We dev eloped a compact InP -based DP -IQ modulator for small -form -factor pluggable coherent transceiver s. The modul ator achieves 112 -Gb/s DP -QPSK modulation with a driving voltage of 6 V pp d . In addition, it provides 86 -Gb/s DP -16 QAM signal generation and 240 -km t ransmission with negligible degradation of BER performance . The half -wavelength voltage of our recent device is 1.9 V , and a high median extinction ratio of over 32 dB was achieved for more than 1,400 child MZ modulators . W e have also propose d an athermal InP -based twin IQ modulator that enables us to use a modulator in a TEC -free operation. It contributes to lowering the power consumption of transceivers. Under a constant driving condition, there is l ittle change in 56 -Gb/s x 2 QPSK modulation characterist ics in the range of 20 to 80 °C . Keywords: Optical IQ modulator , InP , Digital coherent technology, High -order modulation formats 1. INTRODUCTION Digital coherent technology with advanced modulation formats is a key technology for increas ing the transmission ca pacity of optical fiber communication s networks. 100 -Gb/s dual -polarization quadrature phase shift keying (DP -QPSK) systems ha ve already been put into commercial service from long -haul transmission networks . The first - generation form factor of the coheren t transceiver was 5x7 ´ MSA, which employed a LiNbO

効果的な麻酔前投薬方法を評価するため、猫の臨床例30頭に対して中用量メデトミジン（MED）500 μg/m2-低用量ブトルファノール（BTR）0.2 mg/kgおよび低用量MED250 μg/m2-高用量BTR 0.4 mg/kg 併用と高用量MED1,500 μg/m2単独とを比較検討した。すべての猫は、上記いずれかの前投薬後、麻酔マスクによるイソフルラン吸入麻酔下で不妊または去勢手術を施された。高用量MED単独および中用量MED-低用量BTR併用では心拍数減少、体温下降、覚醒時間の延長が認められたが、低用量MED-高用量BTR併用では、これらの反応は認められなかった。副作用として高用量MED単独では数例の猫で嘔吐がみられたが、MED-BTR併用では、一例も認められなかった。また、これらの前投薬により、すべての猫で臨床的に有用な鎮静効果が認められた。高用量MED単独では、覚醒時および覚醒後にやや興奮する症例がみられたが、MED-BTR併用ではほとんど認められなかった。猫におけるMED-BTR併用筋肉内投与は十分な鎮静効果、MEDによる嘔吐の防止、円滑な麻酔からの覚醒など麻酔前投薬として有用な効果を持つことが示唆された。

We investigated an optical frequency comb generated by an InP-based semiconductor Mach-Zehnder (MZ) modulator by using a numerical model that takes into account the nonlinear change of a refractive index and an optical absorption induced by an applied voltage in the modulator. Such nonlinearities are negligible for conventional LiNbO3-based MZ modulators but not negligible for semiconductor MZ modulators. The numerical model quantitatively reproduced our experimental data reported previously. We found that the nonlinearities play an important role to obtain the flat 9-channel optical frequency comb block with an intensity deviation of less than 1 dB, when a moderate RF drive voltage of < 5 V was used. This result was sustained regardless of an RF drive voltage ratio between two arms in the MZ modulator.

A technique that can expand the number of wavelengths while keeping the spacing of the wavelengths constant is in great demand for wavelength-division-multiplexing (WDM) optical communications. We have developed such a technique by employing a fibre loop that contains a pulsed serrodyne modulator (i.e., a serrodyne phase modulator for pulsed light). The modulator shifts the envelope of the discrete spectrum while maintaining the mode positions of the spectrum, and the loop combines the shifted spectra into a broad spectrum. Using that technique, we have experimentally generated ~100 wavelengths with an equal spacing of 0.1?nm (or 12.5?GHz) from ~3 input wavelengths. In this article, we numerically simulate the broadening of the spectrum and confirm that it agrees well in shape and size with that in the experiment, which indicates that our theoretical model is suitable for understanding the experimental results. Employing the same model, we find that the number of wavelengths is increased markedly when the compensation of the fibre dispersion is achieved appropriately.

Dinotefuran ((RS)-1-methyl-2-nitro-3-(tetrahydro-3-furylmethyl)guanidine) is a new neonicotinoid which has a characteristic (±)-tetrahydro-3-furylmethyl moiety instead of the pyridine-like moiety of other neonicotinoids. A series of dinotefuran derivatives were synthesized and tested against hemiptera. SAR (structure-activity relationships) of the nitroguanidine part of dinotefuran are summarized as follows: (1) the mono-methyl group as a N-substituent gave the best activity for the acyclic nitroimino and nitromethylene compounds, (2) the acyclic compounds showed the same activity as the cyclic compounds against Nephotettix cincticeps and were superior to them against Laodelphax striatellus, (3) N-acylation of this series scarcely changed the level of activity. On the basis of these results, we selected dinotefuran for development. © Pesticide Science Society of Japan

The stability of the extinction characteristics of an InP-based Mach-Zehnder modulator is clarified in detail. The changes in the half-wavelength voltage (Vπ) and null point voltage (Vnull) are investigated under long-term high-temperature aging tests. The time correlations with the change in Vπ and Vnull are different from each other. By using a statistical treatment of the Weibull distribution, the degradation modes of the changes in Vπ and Vnull are clarified as a wear-out failure and an early failure, respectively.

We generated 100-1000 channel optical carriers from a single supercontinuum source and confirmed that these optical carriers have a sufficient SNR to achieve Q-factors of more than 18 dB. The channel spacing is strictly determined by the microwave mode-locking frequency with accuracy in kilohertz. The generated optical carriers can be applied to DWDM systems and optical frequency standards.

We report an athermal InP (110) optical modulator with a simple planar n-SI-n heterostructure. A symmetrical push-pull operation provides a high-extinction ratio of >25 dB over the entire C-band and zero-chirp modulation. A Mach-Zehnder optical modulator (MZM) exhibits a 3 dB-EO bandwidth of 30 GHz and 40-Gb/s NRZ high-speed modulation with wavelength and temperature insensitive operation. We also successfully demonstrate an MZM integrated twin-IQ modulator that exhibits 56-Gb/s × 2 athermal QPSK modulation at constant drive and bias voltages.

Recent progress on time-division multiplexed (TDM) and wavelength-division multiplexed (WDM) soliton transmission is described, in which dispersion management plays an important role in increasing the power margin and the dispersion tolerance. The characteristics of the dispersion-managed soliton are compared with those of return to zero and nonreturn to zero pulses. With a small dispersion swing, the system can still be described as an average soliton using the nonlinear Schrodinger equation, while with a large dispersion swing, the solitonlike steady-state pulse becomes a chirped Gaussian pulse, in which the governing equation is closer to a linear Schrodinger equation with a parabolic potential well. We describe an in-line modulation scheme for up to 80 Gbit/s per channel and its two channel WDM transmission over 10 000 km. Finally, we describe 640 Gbit/s (40 Gbit/sx16 channels) WDM soliton transmission over 1000 km with a dispersion-managed single-mode fiber. (c) 2000 American Institute of Physics.

Recent progress on time-division multiplexed (TDM) and wavelength-division multiplexed (WDM) soliton transmission is described, in which dispersion management (DM) plays an important role in increasing the power margin and the dispersion tolerance. The characteristics of the DM soliton are compared with those of return-to-zero (RZ) and nonreturn-to-zero (NRZ) pulses. With a small dispersion swing, the system can still be described as an average soliton with a nonlinear Schrodinger equation (NLSE), whereas with a large dispersion swing, the soliton-like steady-state pulse becomes a chirped Gaussian pulse, in which the master equation is closer to a linear Schrodinger equation (LSE) with a parabolic potential well. An in-line modulation scheme up to 80 Gb/s per channel and its two-channel WDM transmission over 10000 km are described. A 640-Gb/s (40 Gb/s/spl times/16 channels) WDM soliton transmission over 1000 km is also reported with a DM single-mode fiber, without the use of in-line modulation. Finally, dark soliton transmission at 10 Gb/s over 1000 km is described as a different nonlinear pulse application.

We present a traveling-wave-electrode InP-based differential quadrature phase-shift keying modulator with a novel n-p-i-n waveguide structure. The structure features low electrical and optical propagation losses, which allow the modulator to operate at a high bit rate together with a low driving voltage and a low insertion loss. We successfully demonstrate 80-Gb/s modulation with a driving voltage of only 3 Vpp in a push-pull configuration. The chip size is just 7.5 mm times 1.3 mm.

In order to realize ultrafast optical communication in the future, it is necessary to develop a stable short pulse optical source that can be operated in the GHz frequency band. This paper reports the oscillation characteristic of a stable, harmonically and regeneratively mode-locked, fiber laser. This laser can produce stable pulses with a repetition rate of 10 GHz, a pulse width of 1.0 to 3.0 ps and a wavelength of 1.55 μm. Using this laser and a dispersion decreasing erbidium (Er)-doped fiber amplifier, femtosecond pulses with a wavelength of 1.55 μm, a pulse width of 170 to 250 fs and a repetition rate of 10 GHz were generated. Using an optical fiber amplifier with a much higher output power, the average optical output of 0.53 W was obtained, where the peak power of the femtosecond optical pulse was as high as 190 W. Using the 10 GHz femtosecond pulses with high power, pulses with eight wavelengths were generated where wavelengths were between 1.552 and 1.559 μm, and the pulse width and repetition rate were 16 to 17 ps and 80 GHz, respectively. This light source is expected to play an important role in multi-wavelength optical communication. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 80(7): 56–63, 1997

A MZ optical modulator (MZM) with a novel planar structure was proposed. A single-RF drive push-pull MZM with a simple coplanar waveguide (CPW) was fabricated by utilizing a (110)-oriented InP substrate in terms of the crystallographic orientation dependence of the electro-optic Pockels effect. The device exhibits a 3 dB-EO bandwidth of 30 GHz and 40 Gb/s NRZ high speed modulation.

A nine-channel optical frequency comb block with a low intensity deviation is generated successfully by adopting an asymmetric push-pull drive method for a symmetric dual drive Mach-Zehnder modulator. The flat-top optical frequency comb block with an intensity deviation of less than 1 dB is realized for the first time by using a compact and low-drive voltage InP-based Mach-Zehnder modulator.

A new extracapsular technique for repair of canine cranial cruciate ligament rupture using an ethylene tetrafluoroethylene (ETFE) tie was presented. Eighteen dogs (body weight: 6.0-46 kg) with this problem were used for this study. The advantages of this method were 1) the operation was easily performed. 2) Joint could be stabilized by proper fixation with microadjustment during operation. 3) This method presented less surgical invasion than the intracapsular one, since wide incision was not conducted over peripheral tissue of the stifle joint.

We propose a new scheme based on pulsed serrodyne modulation in an optical ring circuit designed to increase the number of wavelengths of optical pulses from a pulse-type multiwavelength light source. As the optical pulses circulate around the ring, the shift in the pulse wavelength increases as a result of the pulsed serrodyne modulation in the ring. By combining the shifted wavelengths of pulses with different round trips in the ring, we can produce a multiple wavelength output with a broad bandwidth. We calculated the spectral characteristics of the multiple wavelengths and confirmed the performance of the scheme experimentally.

We present a traveling-wave-electrode InP-based Mach-Zehnder (MZ) modulator that employs an n-p-i-n waveguide structure. The structure provides low electrical and optical propagation losses, which enables the modulator to operate at a high baud rate with a low driving voltage and a low optical insertion loss. We developed a compact 40-Gb/s differential phase shift keying (DPSK) tunable wavelength transmitter module, which incorporates a full C-band tunable laser and the MZ modulator in one package. The RF driving voltage for the MZ modulator is 3 Vpp in a push-pull drive configuration. Using the same design for the MZ modulator, we also developed a differential quadrature phase shift keying (DQPSK) modulator or optical IQ modulator, and acheived 80-Gb/s DQPSK modulation. Furthermore, we fabricated a compact dual-polarization (DP) QPSK modulator by using the hybrid integration of an InP twin-IQ modulator and a planar lightwave circuit (PLC) polarization multiplexing circuit (PMC). We successfully demonstrated 112-Gbit/s DP-QPSK signal generation.

We propose an optical quaternary minimum shift keying technology with direct modulation for the first time. Error-free operation is obtained by using a digital coherent demodulator employing 1-bit delay detection and an adaptive FIR filter.

We clarified the degradation modes of an InP-based semiconductor optical Mach-Zehnder modulator (MZM) using high-power light-injected accelerated aging tests. Degradation clearly occurred at the light injected side of the edge on the electric field applied region. We found that the degradation threshold depends strongly on temperature, wavelength and bias voltage. By correlating these parameters, we propose a degradation model based on the concentration of the optical absorption current, which depends on the optical absorption coefficient. By employing the degradation model, we obtained the degradation activation energy for a semiconductor MZM for the first time, and the value was 0.45 eV. These results indicate that a semiconductor MZM is sufficiently reliable for use in actual optical communication systems.

We realized high-speed and low driving voltage InP-based Mach Zehnder modulators with an npin high-mesa waveguide structure and traveling-wave electrodes. A full C-band 40-Gbit/s DPSK signal was successfully generated using a compact tunable wavelength transmitter module, which incorporated a tunable DFB laser array as a wavelength tunable laser and an InP MZM in one package. The MZM had a low driving voltage of 3 V pp in a push-pull driving configuration. We have demonstrated 112 Gbit/s RZ-DP-QPSK modulation using two InP MZM modules. One modulator was used as a pulse carver in a push-pull configuration, and the other was used as an IQ modulator in a dual-drive configuration. Since we used an RZ pulse carver to remove the transient region, we obtained clear eye openings without any amplitude ripple. We also demonstrated 50 Gbit/s (12.5 GSymbol/s x 4) 16QAM signal generation employing a novel dual-drive modulation method consisting of a single MZM. We utilized the electro-absorption characteristics of an InP semiconductor to adjust the QPSK amplitude. We confirmed that a single MZM operated as a DPSK, a QPSK, and a 16QAM modulator with the same device. We believe these modulators to be suitable for next generation optical transmission systems.

We fabricated an ultra-compact InP-based DP-QPSK modulator by the hybrid integration of an InP twin-IQ modulator and a PLC polarization multiplexing circuit for the first time. 112-Gb/s DP-QPSK modulation is successfully demonstrated.

Ultra-high speed optical soliton transmissions over 1000 km achieved through the use of lumped erbium-doped fiber amplifiers are described in detail. In a 10 Gbit/s experiment, a bit error rate (BER) of below 1 × 10−13 was obtained with 220−1 pseudorandom patterns and the power penalty was less than 0.1 dB. In a 20 Gbit/s experiment optical multiplexing and demultiplexing techniques were used and a BER of below 1 × 10−12 was obtained with 223−1 pseudorandom patterns under a penalty-free condition. A new technique for sending soliton pulses over ultralong distances is presented, which incorporates synchronous shaping and retiming using a high-speed optical modulator. Some experimental results for a transmission over 1 million km at 7.2 ∼ 10 Gbit/s are described. This technique enables us to overcome the Gordon-Haus limit, the accumulation of amplified spontaneous emission (ASE), and the effect of interaction forces between adjacent solitons. It is also shown by computer runs and a simple analysis ...

We propose a novel 16QAM signal generation method using a single Mach-Zehnder modulator. We successfully demonstrate 50 Gbit/s 16QAM signal generation with a dual-drive npin InP Mach-Zehnder modulator using amplitude control by electro-absorption.

Since the storage of the amplified spontaneous emission (ASE) noise of an amplifier is a cause for the degradation of the transmission characteristics in a long distance soliton transmission using an optical amplifier, the reduction of the ASE is a key issue to be solved for a soliton transmission. A new method to remove the ASE noise using the threshold characteristics (self switching) of a nonlinear amplification loop mirror (NALM) which utilizes the difference in intensity between the soliton signal and the ASE noise is presented in this paper and its application to a transmission experiment is discussed. First, the transmission characteristics of the NALM for a pulse signal are examined. It is demonstrated that the ASE noise can be successfully removed from the pulse signal of high level. The present method is applied to a soliton signal transmitted over 500 km at 10 Gbit/s. The ratio in intensity between the soliton signal and the ASE noise is improved when the NALM is used as compared to the case without it. Finally, it is shown that the switching of pulse close to the transform limit is possible when the phase difference of a pulse peak propagating in a nonlinear loop with a high gain optical amplifier is less than 0.3 π.

単純X線像において, 肝臓内に大小不同のX線不透過性陰影を認めた狆種3例のうち, 2例について剖検を行ったところ, このX線陰影は胆管結石であった。分析の結果, その結石の主成分はヒトでもまれな炭酸カルシウムであった。これらの症例では, 食餌その他の栄養学的共通点がないことから, この犬種における特有の因子が存在する可能性も示唆された。

単独ではべシクルを形成する分子,L-α-ジパルミトィルホスファチジルコリン(DPPC)とミセルを形成する分子,α-[p-(1,1,3,3-テトラメチルブチル)フェニル]-ω-ヒドロキシポリ(オキシエチレン)(Tritan X100)を混合したハイブリッド型分子集合体は組成や温度を変えることにより,活性トリペプチド(N-ベンジルナキシカルボニル-L-フェニルアラニルーレヒスチジル-L-ロイシン)触媒による長鎖アミノ酸エステル基質(N-ドデカノイル-D(L)-フェニルアラニン=p-ニトロフェニルエステル)のL体優位の不斉加水分解を制御できることが明確になった。これらリン脂質型ハイブリッド分子集合体を用いることにより,相転移に非常に近い温度で特異的に高い不斉選択性が発現できた。この事はハイブリッド型分子集合体の直径や疎水性領域の流動性などの種々の物理的特性が相転移温度付近で鋭く変化することと関連していると考えられる。

We have successfully demonstrated 112Gbit/s DP-QPSK modulation using a wavelength tunable pulse carver module, in which a wavelength tunable DFB laser array (TLA) and an InP n-p-i-n Mach-Zehnder modulator are co-packaged, and a dual-drive InP Mach-Zehnder IQ modulator module.

Two platelet activating factors (PAF) were conveniently prepared from optically active epichlorohydrin via 5 steps in 15–16% total yield. Four analogues containing oleoyl, propyl, p-trifluoromethylphenoxy, and N,N-dimethyldithiocarbamoyl groups were also prepared.

A 40-Gbaud tunable transmitter module was developed for the first time by the hybrid integration of a full C-band tunable laser and an InP Mach-Zehnder modulator. Wavelength-tunable chirpless 40-Gbit/s DPSK modulation was successfully demonstrated.

Geographic comparisons of 25 skull and four external characters of the Japanese hare ( Lepus brachyurus ) revealed that hares from Nishinoshima and Dogo of the Oki Islands and hares from Shimane Prefecture on mainland Honshu are distinct. The Oki Islands hares are larger in overall body size, but have shorter ears and hind feet than mainland hares; Oki Islands hares also are smaller in overall size of skull, but the postorbital width and the length of frontal bone are larger. Skull shape is different between Nishinoshima and Dogo, and length of head and body and length of ear are smaller in Nishinoshima than in Dogo. Interisland variation likely was caused by random changes due to genetic drift, bottleneck effects, or founder effects.

Two platelet activating factors (PAF) were conveniently prepared from optically active epichlorohydrin via 5 steps in 15–16% total yield. Four analogues containing oleoyl, propyl, p-trifluoromethylphenoxy, and N,N-dimethyldithiocarbamoyl groups were also prepared.

A 52-year-old woman who was a pet trimmer by occupation and had four cats, presented with cold-like symptoms. Her chest radiograph and CT scan on admission showed a tumor about 4cm in size with spicula and ground-glass opacity in the right middle lobe. We performed fiberoptic bronchoscopy and CT-guided percutaneous needle lung biopsy on the suspicion of lung cancer, but the tissue consisted largely of granulation tissue with eosinophilic infiltration and no findings of malignancy. The cold-like symptoms subsided and C-reactive protein became within the normal range. Because of the histological findings, her occupation and her pets, we suspected pulmonary dirofilariasis. We asked the National Institute for Infectious Diseases for specific IgG antibody assays to various parasite antigens, which showed positive finding for pulmonary dirofilariasis. We therefore diagnosed pulmonary dirofilariasis and did not perform an operation.

Recently, drop test reliability has become a major concern for mobile electronic products . Especially, system-in-package (SIP) like stacked-die-package and package-on-package may lead to increased stress in solder joints during drop impacts due to their complicate structures. In this study, the evaluation of drop test reliability was performed for SIPs using modeling and drop test. 3D-dynamic nonlinear finite element analyses were performed for drop test modeling. After the correlation was observed between modeling and drop test, the optimization of material properties was studied for these packages.

We have demonstrated a 100-Gb/s single channel transmission over the longest distance of 6,000 km ever reported using 2-subcarrier no-guard-interval PDM CO-OFDM. The unique DSP technology enabled to compensate for CD up to 109,200 ps/nm.

The optimum composition (32 mol% DPPC/68 mol% Triton X-100) hybrid-assemblies presented the highest enantioselectivity and the markedly enhanced enantioselectivity was observed at the phase transition of liposomes composed of 65 mol% DPPC and 35 mol% Triton X-100.