摘要:

AbstractThis paper describes a monolithically integrated light source module of a high‐speed/low‐driving voltage multiquantum well (MQW) optical modulator and DFB laser for 1.55‐μm applications. This paper investigates: (1) device structure suitable for growing high‐quality crystal, (2) efficient performance due to adoption of a strained InGaAsP MQW, (3) reduction of device capacitance using polyimide at the electrodes of the optical modulator, and (4) realization of a monolithically integrated module using lens coupling.In the test device, the oscillation threshold current was below 15 mA, the extinction ratio was over 20 dB when the bias voltage was −2 V, the frequency band was 15 GHz (−3 dB), and the optical power coupled to an optical fiber was 2.5 mW. Optical modulation at 15 Gb/s was carried out at a driving voltage of 1 Vp‐p. When this device was used under 2 Gb/s high‐speed modulation using a driving voltage of 2 Vp‐pfor 100‐km transmission, the minimum optical power sensitivity was −23 dBm and the power penalty was 1 dB. This result indicates that this monolithically integrated optical source is suitable for large‐capacity/long‐dist

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780101

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper proposes a method to realize a highspeed processing of image data utilizing the analog memory function of the optical neurochip. The result of experiment also is presented. The features of the proposed method are that the image data can directly be processed in the two‐dimensional form and a large‐scale problem can be processed with a high speed by utilizing the spatial parallelism of the light.In this paper, it is shown first that the variable sensitivity photodetector, which is the basic element of the system, can function as the optical analog memory, where the value proportional to the product of the input light intensity and the control voltage is stored hi the element as the light detection sensitivity and the stored value can be read by the optical signal. Then the application of the optical analog memory function to the image processing is considered. The optical neurochip is constructed by integrating the variable sensitivity photo‐detector in a two‐dimensional array, and it is shown that the difference of two input images can be calculated. The function is realized by selecting the polarity of the control voltage in inputting the pattern.Lastly, the image difference function is applied in the experiment for the selective detection of the moving object where the dynamic image is used as the input. In other words, the light irradiated from the moving object is used as the input pattern; and it is shown experimentally that the trajectory of the moving object is detected but the signal is not detected when the object i

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780102

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

年代:1995

数据来源: WILEY

摘要:

AbstractVertical photonics is the technique of direct integration of optical functional devices or their integration into optical fibers. In optical fiber systems, it is usually very difficult to match the modes of optical fibers to those of minute devices or to adjust their positions accurately. To solve such connection problems, the expanded core fibers are used, the aperture of the device is enlarged, and the optical path is shortened. In this paper, the concept of vertical photonics is discussed and the present status of the basic components (wavelength filters, polarizers, polarization splitters, etc.) and optical devices (isolators, optical switches, wavelength tunable filters, amplifiers, etc.) is reviewed.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780103

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

年代:1995

数据来源: WILEY

摘要:

AbstractFor optical communication technology, which has been pushing for higher speed and larger capacity in the transmission trunk lines, the urgent tasks are not only improvements in performance but also the expansion of applicable areas by introducing new functions and moving into new phases.For optical fibers to be applicable in access net, subscriber loop, intrastation transmission systems, and interprocessor connections, the realization of optical links that are easy to use, easy to fabricate; and inexpensive, is strongly demanded. Also, the appearance of optical nodes everywhere in the broad bandwidth network that will be the backbone of the multimedia society would not be too far off. Research on integrated optical devices and circuits that have new structures for waveguide‐type devices, array components, or two‐dimensional devices, is continuing to progress to meet these demands.To mount these devices and circuits compactly and inexpensively into packages and modules, innovative packaging techniques have to be developed correspondingly. From this viewpoint, this paper reviews optical packaging technology, which holds the key to the realization of integrated photon

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780104

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

年代:1995

数据来源: WILEY

摘要:

AbstractAs monolithic integration of the microwave circuits progresses, the microstrip line used as a fundamental transmission medium becomes extremely small in size. As the transmission line is miniaturized, it becomes necessary to consider the effect of the shape of the edges of the strip conductor in addition to the thickness. In this paper, an integral equation is derived for the charge density distribution on the strip conductor surface as the unknown. The transmission line characteristics are obtained by discretizing the integration range. Further, the effect of the trapezoidal cross section of the strip conductor formed by etching and plating on the characteristic parameters is specifically studied.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780105

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn this paper, a method for computing aQvalue is proposed, which is believed useful for a highQcavity. In this method, theQvalue is derived from the input excitation energy and the stored energy in the process of increasing amplitude of the electromagnetic field in the cavity. This method is applied to a rectangular cavity without an aperture and theQvalue obtained has an error of only approximately 1 percent.In this paper, a cylindrical cavity without an aperture is used as an example and the surface processing is investigated by means of the electromagnetic field distribution in the cavity and the wall loss. In the stair‐stepped approximation of the cylindrical wall surface, the electromagnetic field is disturbed significantly near the wall in the case of the TM010and TM011modes which have magnetic fields in the azimuthal direction. In addition, theQvalue is higher by 21 × 32 percent and the computed wall loss is too small. Using CP method analysis, in which the integration path is modified to fit the boundary for wall processing, both the electromagnetic field and the wall loss are computed accurate

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780106

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

年代:1995

数据来源: WILEY

摘要:

AbstractA numerical approach based on the vector finite‐element method using hybrid edge/nodal elements and full components of electric or magnetic field is proposed for analysis of three‐dimensional chirowaveguides. Chiral‐loaded circular waveguides and buried circular chirowaveguides are analyzed using the present method, and then the validity and usefulness of the method are discussed based on the detailed numerical accuracy ana

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780107

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe beam propagation method (BPM), used widely for analyzing optical waveguides and optical circuits, is also being applied to devices that include nonlinear materials. However, in the analysis of nonlinear optical devices using the conventional BPM, in many cases it is assumed that the field intensity distribution does not change within the step length in propagation direction. Therefore, for accurate calculation, the step size in the propagation direction must be extremely small, which results in long calculation times.Therefore, this paper proposes and formulates a numerical method where the solution is forced to converge by the iterative calculation of a difference equation over each propagation step of the Crank‐Nicolson BPM method. Using this method, first, we analyzed the case where the fundamental TE mode propagates in the dielectric slab waveguide that has a Kerr‐like nonlinear cladding. By calculating the emission angle of the optical beam into the cladding, the present method is compared with the conventional method. After it is demonstrated that this present method is effective, the dependency of the optical beam emission angle for the incident power is shown. Furthermore, the effect of the beamwidth on the excitation is analyzed in the case where a nonlinear stationary wave is excited by a Gaussian beam and the interesting results are pro

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780108

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

年代:1995

数据来源: WILEY

摘要:

AbstractAn LiNbO3single crystal has large electromechanical coupling efficiency, and its elastic loss is small. Using the elastic energy trapping phenomenon of an LiNbO3single crystal, a piezoelectric transformer can be formed using a width‐shear mode. To reduce the internal loss, a high‐order mode of width vibration is used and multiple pairs of interdigital electrodes formed on the top and bottom surfaces of a piezoelectric substrate are used for both input and output.To analyze the performance of a piezoelectric transformer with interdigital electrodes, Mason's equivalent circuit is used. Finally, the relationship between the designed parameter by the new equivalent circuit and the characteristic of a piezoelectric transformer is investigated to compare the theoretical and experimental results. In particular, it is proved that the ratio of input voltage to output voltage is determined by the load to the transformer and the number of interdigital electrode pairs for the input and out

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780109

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper reports an active integrated antenna which combines the antenna function with the millimeter‐wave MMIC technology. TJI addition to a high carrier frequency, the compactness of the circuit is extremely useful for applications to automobile radar and wireless LAN.To realize low‐cost millimeter‐wave subsystems, this paper describes an active integrated antenna making use of the slot antenna and the second harmonic of the FET oscillator. The input impedance of the slot antenna is included in the design of a strongly coupled active integrated antenna array. The oscillation frequency of the array was evaluated by a large signal analysis.In the case of a two‐element active integrated antenna using a harmonic, the second harmonic operating frequency of 39.3 GHz was obtained. The phase of the radiation of the fundamental mode was adjusted so that different radiation patterns for different modes were obtained. Also, in the uniplanar‐type four‐element array, a large signal analysis was carried out including the discontinuities in the coplanar waveguide. Through the present trial fabrication, the fundamental data for fabrication of millimeter‐wave monolithic active integrated antennas

ISSN:8756-663X    

DOI:10.1002/ecjb.4420780110

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

年代:1995

数据来源: WILEY