摘要:

AbstractTo date, frequency stabilization methods for semiconductor lasers mainly use the absorption line of an atom or molecule to modulate the frequency of laser light slightly so as to obtain a control signal. As a result, an oscillation bandwidth broadening will appear and the stabilization point will be restrained at the center frequency of the absorption line. This paper reports a frequency stabilization method using a magneto‐optical effect, the Faraday effect of an atomic absorption line, instead of direct modulation of the oscillation frequency. This stabilization method made it possible to control the stabilization point frequency by changing the dc magnetic field. With an Rb absorption line as the frequency reference, the controlled frequency range was about 1.5 GHz, which is wider than the Doppler width of the Rb absorption line at room temperature. The experimental results were consistent with the theoretical analysi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760501

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

年代:1993

数据来源: WILEY

摘要:

AbstractA method for feature extraction and an optical neural network model which can easily be implemented in optics have been proposed. In the method, the vector feature which denotes direction, existing position, and length of the line segments included in the pattern is extracted without any negative synaptic weights. It has been shown analytically that the vector feature is superior to the conventional mesh feature for handwritten character recognition.The model using the method is featured as follows: (1) high recognition ability to recognize handwritten characters by extracting vector feature; (2) fast learning convergence; and (3) possibility of all‐optical implementation. By applying a newly developed feature‐extracting optical neuron device to the model, an optical neural network for handwritten character recognition has been constructed. It has also been confirmed that the feature‐extracting optical neuron device can extract four kinds of line segment in parallel processing. Due to the optical parallelism, the device is substantially useful for implementation of massive sy

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760502

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

年代:1993

数据来源: WILEY

摘要:

AbstractAs materials for a polarizer with a large aperture and short length, stretched gold island films with large optical anisotropy have been fabricated and their optical properties have been investigated experimentally. By embedding an island film into a glass medium and stretching the embedded film with large tension, large optical anisotropy can be achieved. When a 90‐Å thick gold island film deposited on a soda‐glass substrate and embedded in a 0.35‐μm thick pyrex glass was stretched five times with a tension of 0.23 kg/mm2at 650°C, the resonance wavelength of the film changed from 0.54 to 0.95 μm in light polarized in the stretching direction.In light polarized in the direction perpendicular to the stretching direction, the resonance wavelength showed almost no change and was 0.53 μm. The multilayer consisting of the anisotropic island films can be used for a thin optical polarizer with a larg

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760503

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

年代:1993

数据来源: WILEY

摘要:

AbstractResonance and loss characteristics of whispering gallery modes in a dielectric disk resonator are discussed three‐dimensionally by using an approximate variable separation method. A radius of the disk is sufficiently large compared to a wavelength. A cylindrical function with a complex order and argument whose absolute values are much larger than unity is included in an eigenvalue equation.In this paper, the eigenvalue equation is solved analytically by using a newly developed calculation method of the cylindrical function. As a result, resonance and loss characteristics of the dielectric disk resonator in a wide frequency ranging from a microwave to optical wave are understood. The present method can be applied to a whispering gallery mode resonator made of lossy dielectric materials. Therefore, one can obtain a radiation loss separately from a dielectric loss based on a loss tangent of the material

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760504

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

年代:1993

数据来源: WILEY

摘要:

AbstractOptical 1 × 3 power dividers composed of coupled waveguides are analyzed using the implicit finite‐difference method and the low‐loss configuration with reduced size is investigated. First, to check the accuracy of the method, the mismatching loss of the eigenmode of a straight waveguide is evaluated and it is verified that the error does not accumulate with the propagation distance.Next, the characteristics of 1 × 3 power dividers using coupled waveguides inclined with respect to each other are investigated and the range of the tilt angle and the effects of the angular error upon power distribution are clarified. To widen the tilt angle, which results in reduced‐size dividers, the corner bends with modified refractive‐index distribution are introduced. As a result, the loss of a 3‐degree tilt angle divider is found to be reduced by more than 1.5 dB due to the introduction of the corner bend with modified refractive‐index

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760505

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe split‐ring resonator made of an open‐ended ring‐shaped stripline connected at its ends with a lumped element capacitance has already been used in practice as a resonator element for an oscillator. If this lumped element capacitance is replaced with a distributed capacitance, the structure can be modified to a hairpin‐shaped resonator with a distributed coupling circuit.This paper studies such fundamental characteristics as the resonant condition of this resonator. In addition, by using its characteristics, applications are proposed for multiple‐stage filters and push‐push oscillators. The design data are organized and a trial fabrication is carried out for verification. The experiment is carried out in the L band. From the results, it is found that the resonator of this configuration is small in size and has high degrees of freedom. The structure can be applied to MIC or MMIC at much higher

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760506

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

年代:1993

数据来源: WILEY

摘要:

AbstractAs a method for guided mode analysis of a planar electron waveguide with an arbitrarily shaped potential profile and an arbitrary effective mass profile, an analysis method based on the finite element method is proposed. The methods for computation are presented for the phase constant, mode confinement factor, and group velocity of the guided mode. Specifically, the present method is applied to rectangular and parabolic electron waveguides so that the validity and effectiveness of the method are presented.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760507

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

年代:1993

数据来源: WILEY

摘要:

AbstractAs a first step toward establishing a methodology for a quantum effect device design, the resonant characteristics in a symmetrical double‐barrier structure were studied and its synthesis problem was investigated. It was found that the resonance levels are not always dependent on the barrier width and the well width. Some are dependent on only one of them or on neither of them. By deriving an equation explicitly expressing each resonance level or its upper and lower bounds, the profile was found. In the synthesis problem, with the barrier width and the well width as variable parameters, the realization of one level given arbitrarily was discussed and the methodology was presented. It was shown that higher‐order resonances of second and third orders can be realized. A synthesis method is presen

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760508

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe FM and digital recording performance of a stretched disk system with a good interface between a perpendicular magnetic recording medium and an MIG‐type ring head has been examined. Little evidence of the low‐frequency enhancement and high‐frequency suppression effect has been found in a short wavelength FM recording. No reversal noise was detected at a carrier wavelength of 0.3 μm in a short wavelength static image recording. However, a harmonics distortion and a cross‐modulation distortion were found to be significant and are believed to be due to a sharp transition of the magnetization direction of the medium, which is not suitable for two‐signal multiplex recording.On the other hand, the error rate of digital recording is found to depend on signal‐to‐noise ratio (SNR) for a longer wavelength and a peak shift pattern for a short wavelength recording. The error rate better than 10−4was obtained by using PRIV coding at 0.88 μm2/bit (Tw= 5 μm, λ = 0.35 μm). This result demonstrates the applicability to a high‐density recording. By improving a frequency response of a head and medium and by optimizing further pulse slimming, the wavelength limitation for error rate due to a peak pattern shif

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760509

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

年代:1993

数据来源: WILEY

摘要:

AbstractConventional high‐density digital recording using a rotary head requires a high‐accuracy servo system with a high precision in mechanics. By combining double‐track scanning and data rearrangement, a nontracking method by which all data can be reproduced in order has been developed. By using this method, it is shown that a tracking accuracy of ± 100 μm for a track pitch of 9.8 μm is obtained compared to a conventional value of ±5 μm. A stamp‐sized cassette and a compact digital audio tape recorder are developed using this nontracking method and evaporated

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760510

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

年代:1993

数据来源: WILEY