摘要:

AbstractTo overcome various problems in cesium beam resonators using polarized magnetic fields, researches on cesium beam resonators with optical pumping are being carried out. In these optically pumped cesium beam resonators, the frequency fluctuations of the laser diode (LD) used to excite the cesium beam affects the frequency stability of the resonator.This paper proposes a method in which the frequency fluctuations of the laser light are reduced to the noise induced on the control loop of the resonator. In this method, the absorption line of the cesium beam is used as the light standard frequency and the frequency fluctuations of the stabilized LD is determined. Further, such frequency‐stabilized LD is used in an optically pumped cesium beam resonator and its short‐term frequency stability is analyzed. As a result, it is shown that high‐frequency stability s̀yo(γ)<10−13/τ is achievable while the cesium beam intensity and absorption linewidth remain the same as those of present small

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe problems of reflection and transmission of a plane wave incident at an arbitrary angle on a silicon slab containing optically induced plasma are analyzed by a step‐approximation method under the assumption that the plasma is distributed inhomogeneously in the direction of the slab thickness. It is found that the TM incidence is influenced more than the TE incidence by the plasma in the reflection coefficient vs. the incident angle. Especially, the effect near the Brewster angle is significant. On the other hand, a plasma is generated in a high‐resistivity silicon slab by means of light‐emitting diodes. A millimeter‐wave at 35 GHz is incident at an arbitrary angle on the slab. The experiments on the reflection and transmission are carried out and the results are compared with the theoretical results. It is found that the reflection characteristics of the millimeter‐wave can be controlled at a modulation rate of about 1 percent and the response speed of the plasma

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper describes the NRD guide (nonradiative dielectric waveguide) proposed as a new type of dielectric transmission line for millimeter‐wave integrated circuits. After the operation principle and the modes of the NRD guide are explained briefly, the nonradiative and low‐loss nature of practical importance are confirmed experimentally. Next, the behavior of the transmitted wave in a bend is studied. Configurations and characteristics of typical NRD guide circuit elements, such as a matched terminator, a directional coupler, a circulator, a beam lead diode mount and a Gunn diode oscillator also are discussed. Using these circuit elements, a transmitter and a receiver are fabricated at 35 GHz and their performances are evaluated. The dimensions of the transmitter and the receiver are as compact as 68 mm × 66 mm and 85 mm × 75 mm in area, respectively. The output power of the transmitter is 10 mW and the temperature coefficient of the frequency is 0.57 ppm/°C. The temperature coefficient of the receiver also is as small as −0.76 ppm/°C. The noise figure is measured to be 10.6 dB. This value is obtained by using Si diodes in the mixer. Finally, as particular applications of the NRD guide, a filter, a power divider, and a leaky‐wave antenna ar

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractWavelength tunable lasers are considered to be used for a wide range of applications such as local oscillator lasers for coherent communication, lasers for wavelength multiplexed communication, and improvement is expected by wavelength matching. So far, various wavelength tunable lasers have been reported. In particular, since diffraction grating integrated lasers such as DBR and DFB lasers can provide wavelength tuning operation by current injection, they have actively been researched and developed. This paper discusses the wavelength tuning principle, structures, and characteristics for these monolithic wavelength tunable lasers.The widest range of wavelength tuning, approximately 10 nm of tunable range, has been obtained by a three‐region DBR laser with a phase control region, but it has a complex structure and there are problems of low light output power and linewidth broadening associated with wavelength tuning. Although any DFB type tunable laser exhibits a small continuous tunable range of at most 2 to 3 nm compared to DBR type, it can provide a narrow linewidth and has an advantage of simple structure. Here, we show that these tuning ranges are theoretical limits, and further improvement in the wavelength tuning range requires the development of new technolog

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractSemiconductor lasers which oscillate at a single frequency have been developed. DFB lasers represent such lasers. Since coherent optical communication has many merits, e.g., longer distance between repeaters, many applications of such lasers have been investigated.In this study, the frequency characteristics of these lasers have been evaluated. In a conventional DFB laser, the frequency characteristic degrades when frequency modulation is carried out around several Megahertz.To solve this problem, a method to control the spatial hole‐burning phenomenon was investigated using a multielectrode DFB laser with a long cavity. As a result, a flat frequency modulation characteristic at frequencies from 100 kHz to 15 GHz was obtained and it was confirmed that this DFB laser was suitable for coherent optical communication system

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractIn large‐capacity, high‐speed and long‐distance optical communication systems, an optical isolator is one of the key devices for stable laser diode operation.This paper discusses first the required characteristics of an optical isolator, and then features of its various types based on connection with surrounding optical circuit are described. Next, the stage of the art of the magnetooptical materials required for optical isolators and the magnetic circuit design are reviewed; and, finally, recent developments of optical isolator devices are rep

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe conventional finite‐element method for the analysis of electromagnetic fields excited by the electric current is based on the potentials. However, as the potential is an indirect quantity, the numerical accuracy obtained by those methods is not so high and the fixation of the gauge condition is troublesome.This paper proposes a finite‐element analysis method based on the electric or magnetic field intensity to determine the electromagnetic fields excited by electric current. As the electric or magnetic field intensity is a direct field quantity, the numerical accuracy of this method is better and the problem of the gauge condition does not arise. Moreover, it is shown that this method can be applied not only to the dynamic electromagnetic fields # 0 but also to the static electromagnetic fields ω

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe 0.98‐μm InGaAs strained quantum well (QW) lasers have been fabricated. In these lasers, improvement in laser performances such as low threshold characteristic and applicability as a pumping source of Er‐doped fiber optical amplifiers are expected. The measured transparency current density and differential gain coefficient of the strained QW lasers show that they have a higher potential for low‐threshold current operation than conventional lattice‐matched GaAs QW lasers. A threshold current of 3.3 mA has been achieved in a ridge waveguide structure with high‐reflective facet coatings. A maximum output power of 85 mW and an external differential quantum efficiency of 62 percent have also been obtained by anti‐reflective and high‐reflective

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe magneto‐optical properties of various transparent plastic materials have been measured. It has been clarified that the Verdet constants of polystyrene derivatives are larger than those of NaCl crystal and the light flint glass, and that the value of the figure of merit reaches a maximum at the short wavelength region below 500 nm.An optical isolator using poly‐α‐methylstyrene gives an isolation ratio of 20 dB at 488 nm, showing, for the first time, a possibility of a low‐cost plastic optical isolator. The magneto‐optical properties of these plastics also enable the optical measurement of high magnetic field or hi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractIt has been reported that when polycrystalline silicon is used for the active layer in an MOS transistor, the breakdown voltage in the drain junction is low and the junction leakage current is high.In this paper, the behavior of the drain junction was analyzed and the optimum design was carried out. It was found that in the drain junction, the current generated at the Si‐SiO2interface predominates when the electric field is low and the tunnel current predominates when the field exceeds 2 × 105V/cm.To improve the junction characteristic without degradation of the transistor driving efficiency, a high‐resistance drain was used. As a result, it was found that the optimum resistance was 5 to 100 kohm/sq. To control this resistance, it is important to minimize the local state density. To achieve this goal, the polycrystalline silicon should be 10 to 50 nm thick. The solid‐phase growth technique is effective in improving the crystallinity.This paper will show that it is possible to design a polycrystalline silicon transistor with high breakdown voltage, low leakage current, and high mutual condu

ISSN:8756-663X    

DOI:10.1002/ecjb.4420740210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY