摘要:

AbstractA new optical wavemeter using a quartz azimuth rotator for direct reading of wavelength is described. When linearly polarized light having a certain wavelength enters the quartz rotator the plane of polarization rotates, the angle of rotation depending on the thickness of the quartz and the wavelength. Since the thickness of the quartz in the wavemeter is kept constant, the wavelength can be read from the angle of rotation of the polarized input light. This angle is obtained from the ratio of two polarized light beams which are divided from the input light by using an optical analyzer. The quartz thickness at which the error in measurement of wavelength is minimum is found. The relationship between the dividing ratio of the beams and the wavelength is also found. An azimuth quartz rotator with optimum thickness is fabricated. It is confirmed that the calculated and measured characteristics of the dividing ratio versus wavelength are in good agreement. The wavemeter has a wavelength range of 0.6‐1.6 μm and measurement accuracy better than 1 nm at input power of ‐35 dBm. To increase the utility of the wavemeter, a device to measure its input power with high sensitivity is added to the apparatus, the resulting accuracy being better than 0.1 dB at an input level of ‐

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700201

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

年代:1987

数据来源: WILEY

摘要:

AbstractFerrite, a ferromagnetic material in the form of sintered ferrite and rubber ferrite, is used for electromagnetic‐wave absorbers. However, there is a certain limit to reducing the thickness of the electromagnetic wave absorber using ferrite. For obtaining thin rubber‐ferrite electromagnetic‐wave absorbers, carbon is added to them and their electromagnetic‐wave absorbing characteristics are examined. The results show that the thickness can be reduced to about 30 percent by adding the order of 1 to 10 percent (volume ratio) of carbon to ferrite. The reduction of the thickness of the absorber also reduces its weight. The mixing of carbon is highly effective in reducing the weight of the absorber, since the specific gravity of carbon is smaller than ferrite. This paper presents the electromagnetic‐wave absorption characteristics of carbon‐added rub

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700202

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

年代:1987

数据来源: WILEY

摘要:

AbstractA gate driving method is proposed for a pnpn switch with noise protection capability. In relation to adv/dtprotection circuit, on‐and‐off tests of the switch have been carried out so that the operative and inoperative regions due to switch potentials are determined. If the circuit of the driving current source is of a series‐control type, there is an inoperative (nonfiring) region of about 1 V in terms of cathode potential. In a parallel control‐type circuit, driving is possible in all regions because the currents overlap at the time of switching each gate. On the other hand, in the on‐and‐off switch experiment, it is confirmed that only the combination of a parallel control driving‐type circuit and of adv/dtprotection method by a diode can operate correctly regardless of the swi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700203

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe electromagnetic fields at the facets of optical fibers were analyzed by using a three‐dimensional model, unlike a conventional slab waveguide which is a two‐dimensional model. A closed‐type waveguide model of an optical fiber was analyzed by using the eigenmode expansion method, since the radiation mode in an open‐type waveguide (such as an optical fiber) is difficult to treat and compute numerically. The radiation pattern at the facet was obtained by applying the stationary‐phase method to the electromagnetic field. The radiation pattern of the electromagnetic field of a dielectric rod antenna was also analyzed via the same method, since this is a pattern at the facet of a dielectric cylindrical waveguide. Numerical examples of the reflected and transmitted powers in various cases w

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700204

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

年代:1987

数据来源: WILEY

摘要:

AbstractTo understand the small‐signal gain, signal‐gain saturation and noise characteristics of 1.5 μm InGaAsP Fabry‐Perot cavity‐type laser amplifiers, two types of laser amplifiers having different thickness of the active layers were tested. It was found that the larger the gain coefficient (i.e., the larger the injected carrier density), the higher the gain and saturation output of the amplifiers, and the lower the noise level. Stern's gain calculation method was applied to materials for the 1.5‐μm region. It was found theoretically that these characteristics are due to the dependence of the carrier lifetime on the injected carrier density and the dependence of the saturation intensity and the population inversion parameter of the gain coefficient, by using the material parameters taking account of the Auger effect and the structure parameters of the device. The feature of the 1.5‐μm amplifiers is that the reduction of the carrier lifetime with the increase of the carrier density becomes more significant due to the Auger recombination process. It is important for improving the saturation output by positively utilizing this phenomenon to design the amplifier structure so that the amplifiers can be operated in a hi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700205

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper describes a method of cancelling the periodic noise induced from the power‐line during measurement, using the LMS algorithm and the adaptive periodic noise canceller synchronized to the power‐line frequency. To simplify the analysis, a modelling is made whereby the signal is a random variable and the noise is periodic, containing fundamental and a large number of harmonic components with the power‐line frequency as the fundamental component. A parameter for evaluating the noise cancelling performance of the adaptive periodic noise canceller is derived analytically. It is shown that the processing can be performed without multiplication, without degrading the performance. Then a fast algorithm is proposed for adaptive periodic noise cancellation, which can reduce drastically the computational complexity, thereby degrading the performance little. By applying the algorithm, the realtime processing by a microprocessor is realized with a sampling rate of several kilohertz. Finally, a discussion is made of the effect of digital implementation on the performance, and it is shown that the cancellation of the power‐line interference by the fast algorithm is practically

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700206

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn the CR single‐tuned amplifier in general, it is difficult to realize high selectivity and high amplification when a high tuning frequency is specified. We succeeded in reducing the body effect by using a high‐frequency, field‐effect transistor as the reactance transistor and grounding the CR tuned circuit which is a load to the driving circuit. When a double‐tuned amplifier is constructed by cascading such a circuit in two stages, the frequency bandwidth can be enlarged. A stable amplifier was realized with the center frequency of 455 kHz and voltage gain of approximately 80 dB. This paper analyzes the frequency characteristics of such a CR double‐tuned amplifier circuit, deriving the formula for realizing the required double‐hump characteristics. When a single‐hump characteristic is composed by aligning the double‐tuned amplifier to the same tuning frequency, the selectivity is increased by approximately 55 percent compared with the characteristics of the singletuned amplifier, together with a considerable improvement in the roll‐off characteristics. An experimental circuit was constructed. The measurement of the frequency characteristics agreed well with the result of calculation. The double‐tuned amplifier circuit can be applied to the IF amplif

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700207

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper describes an all‐digital linearity error correction (LECS) method for A/D and D/A converters, and presents the design and performance of single‐chip CMOS LSI converters utilizing this new technique.In general, the deterioration of converter accuracy is caused by discontinuity changes (jumps) of the converter characteristics due to component tolerances in the weighting network. The proposed correction method is based on a design ensuring that only negative jumps occur which are then eliminated digitally by a shifting of digital output (input) codes. Since this method does not require analog circuits, the number of noise sources is minimum and high reliability is achieved by eliminating physical trimming.Experimental CMOS converters have been realized utilizing the proposed method; the D/A converter provides an S/N of 92 dB at 150 ksps, and 87 dB is achieved by the A/D at 78 ksps. Thus, the possibility of realizing high‐quality audio converters by MOS process technology has been demonst

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700208

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

年代:1987

数据来源: WILEY

摘要:

AbstractThere are numerous reports on the numerical analysis of variational expressions for a waveguide with an arbitrary cross section and structure by means of a finite element method. In conventional methods, cumbersome procedures or special programming techniques are required to discriminate the true solution of the guided mode from the spurious solutions. In this paper, a new variational expression for the β propagation constant is derived in which the transverse electromagnetic field componentse.tandhtare used as the testing functions. A method is presented for numerical analysis of this new variational expression by means of the finite element method. It is pointed out that the guided mode and the spurious mode can easily and completely be discriminated by only the realistic condition that the propagation constant of the guided mode is real, without resorting to cumbersome procedures or special programming techniques. The new variational expression is well suited for a finite element analysis and resolves difficulties and ambiguities associated with the finite element methods based on the conventional variational expressions

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700209

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper describes the proposal, design and fabrication, as well as the experimental results of an optical disk pickup constructed with integrated‐optics using thin‐film waveguides. This integrated‐optic device is constructed with a focusing grating coupler, a guided‐wave beam splitter and a photodiode array on an Si substrate which is coupled to a semiconductor laser. The focusing grating coupler and the guided‐wave beam splitter were fabricated by the electron beam direct writing method. The focus spot width of the fabricated device was measured to be close to the diffraction limited value, and the reflected light was detected as photocurrents of the photodiodes. It was confirmed that the device has a capability of detecting focusing/tracki

ISSN:8756-663X    

DOI:10.1002/ecjb.4420700210

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

年代:1987

数据来源: WILEY