摘要:

AbstractSurface‐emitting lasers which emit laser beams in the direction normal to the substrate are attractive devices in applications for two‐dimensional laser arrays and parallel optical communications.Recently, horizontal cavity and bent cavity devices have been investigated. Among such devices, the microvertical cavity surface‐emitting laser, which has a cavity normal to the substrate, has a cavity only several times longer than the wavelength. The length of the cavity in the lateral direction also can be reduced to a size several times longer than the wavelength. Therefore, by using this type of laser, superior longitudinal mode selection, low‐noise operation and low threshold current are expected.Furthermore, a high‐density two‐dimensional array can easily be manufactured with this device and its application to parallel optical communication is expected. This paper will describe our vertical‐cavity,surface‐emitting laser, as well as our view of surface‐emitting lasers now

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730401

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe design method for the polarization‐maintaining optical fiber with two hollow circular pits across the core‐clad interface was investigated under the following two conditions: (1) the total dispersion for one of nondegenerated HE11modes is zero simultaneously at the two wavelengths of 1.30 μm and 1.55 μm (the zero dispersion condition); and (2) the modal birefringence (=B) is maximum. The polarization‐maintaining optical fibers with hollow circular pits across the coreclad interface are the structure which can maximize the modal birefringence in angularly nonuniform refractive index profiles in the case where no dispersion is considered. To satisfy the conditions for (1) and (2), the relative index difference of the core and the clad Δ1, the normalized minimum distance between the core center and the pit peripheryD[Δ(R0‐a3)/a1;R0; the distance between the core center and the pit center,a1: the core radius,a3: the pit radius], and the normalized pit radius (=a3/a1) are used as parameters. The principal results obtained in this paper are as follows. (1) IfDis decreased,Balso reduces sincea3/a1must also be decreased for the zero dispersion condition. (2)Bcan be maximized if two hollow pits are in contact with the core periphery (D= 1.0). (3) When Δ1is 0.5 to 1.5 percent, the attained maximum value ofBis 0.75 × 10−

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730402

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper investigates the radiation and propagation of electromagnetic fields in a uniformly bent section of a rib waveguide connected with the straight section when guided modes are incident from the straight section. The analysis is based on a method in which fields in uniformly bent sections are expressed in terms of a spectral integral of eigenmodes with continuous eigenvalues. Fields propagated along a uniformly curved slab waveguide with finite‐length also are analyzed in detail using the same method for a full numerical investigation of mode transmission and mode conversion characteristics for the slab waveguide structure where two straight waveguides are connected via one finite‐length, uniformly curved sect

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730403

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe propagation constant and the field distribution of the guided modes in a diffused slab waveguide with an inhomogeneous refractive index profile are analyzed by means of the uniform asymptotic series. We used the Airy differential equation as the reference equation to which the Langer transform and the Liouville transform are used repeatedly to construct a uniform asymptotic series solution. If this recursive algorithm is used, an asymptotic solution of an arbitrary approximate degree can be obtained. This uniform asymptotic series solution can be represented analytically by the expansion coefficients of the polynomial approximating the refractive index profile.The propagation characteristics of the guided modes in a diffused waveguide with an index of refraction expressed in terms of an exponential function or an error function are studied and convergence and accuracy of the uniform asymptotic series solution are investigated. The numerical results confirm that the uniform asymptotic series solution agrees well with the rigorous solution or the numerical solution. The propagation characteristics of the guided modes in a diffused waveguide with an exponential refractive index profile have been found with high accuracy. The determination of the propagating modal index is discussed.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730404

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper proposes an analysis method based on the finite‐element method that can be applied to such rotationally symmetric structures as circular cylindrical resonators.In general, the main drawback associated with the finite‐element methods for electromagnetic eigenvalue problems is the mixing of the nonphysical or spurious solutions with the physical solutions. However, in the method proposed in this paper, all the spurious solutions have zero eigenvalues and can easily be separated from the physical solutions, thereby eliminating the problem of spurious solutions. Moreover, the computation can be treated as two‐dimensional, thus a large saving in computer time and storage is obtained compared to three‐dimensional computations.Theoretical equations are derived and by using a numerical example the rightness of this method is demon

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730405

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

年代:1990

数据来源: WILEY

摘要:

AbstractThere are several compound magnetic semiconductors, but they are not very practical because their Curie temperature is below room temperature. The magnetic semiconductor ferrite (MSF) has a ferromagneticity at room temperature as well as a semiconducting resistance and permittivity. The magnetic characteristics of the MSF depend on temperature but not on humidity and gas concentration. Also, the permittivity depends on the temperature, humidity and combustible gas concentration.As an application of these characteristics, a multisensor module is constructed which contains temperature, humidity and gas sensors. In the conventional method, a number of sensors corresponding to the kinds of quantities measured are required. However, in the present system, only one MSF can detect temperature, humidity and combustible gas concentration. Therefore, the number of sensors needed is small and the equipment is simplified. In addition, since these quantities measured can be converted to RF, the system is suited for digital measurement.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730406

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

年代:1990

数据来源: WILEY

摘要:

AbstractAs the degree of integration and speed of VLSI are advanced, the multilayered interconnection techniques become increasingly important. At the moment when the VLSI technology is advanced to 0.5 μm technology represented by 16 MDRAMs, electromigration by the high‐current density of Al interconnections and the stress migration by the stress from the interlayer insulating films are important in reliability of Al‐interconnections. Although the latter can be rectified by low‐temperature formation of the insulating films, the prevention of the former is still in a development stage. Since the spacing between the interconnections and the aspect ratio of the connecting hole increase, good planarization of the interlayer insulating films and buried planarization of the connecting holes are required.These problems can be resolved by directive deposition of the insulation films and selective CVD of W. Further, as the miniaturization and the number of interconnection layers are increased, the crosstalk noise of the device due to the interconnection capacitances becomes significant. It is necessary to reduce the film thickness of the insulating layer and the interconnection so that the interconnection capacitance is reduced. In this paper, first the present status of the fine multilevel interconnections, the problems and solutions are presented. Next, the necessity of reduction of the interconnection capacitance and the prospect of the multilevel interconnection in the future after the 0.5 μm generation are de

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730407

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

年代:1990

数据来源: WILEY

摘要:

AbstractAn optically coupled three‐dimensional common memory has been proposed for more functional and faster parallel processing of information with several CPUs. A detailed design of the memory cell was carried out. First, the effect of stray light which is a significant problem in the design of the optically coupled three‐dimensional common memory was studied quantitatively by deriving the optical coupling efficiency between the light‐emitting and detecting devices. Next, by means of the static analysis taking into account the fluctuations of the device dimensions, alignment error between the layers and the variation of the power supply voltage, the safe operating region of the memory cell was evaluated. As a result, an optimum condition was found on the transverse pitch between the light‐emitting and detecting devices and the supply current to the emitting device for a stable operation of the memory without being affected by the stray light. Further, with this optimum condition, a dynamic analysis was carried out for the memory cell circuit to which the bit‐line peripheral circuit is attached. In the analysis, the reduction of the load resistance of the memory cell by the optical writing was described with an equivalent circuit consisting of resistors and MOSFETs. The analysis was carried out with the driving circuit for the light‐emitting device characteristic to the optically coupled three‐dimensional common memory taken into account. It was confirmed that the memory cell designed by means of this dynamic analysis opera

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730408

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

年代:1990

数据来源: WILEY

摘要:

AbstractThin‐film SOI MOSFETs made in completely depleted SOI films were fabricated by electron‐beam annealing and their electrical properties were compared with those of conventional SOI MOSFETs. The threshold voltage agreed with the calculated value. With complete depletion of the SOI film, the threshold voltage decreased toward the value determined by the work function difference between the gate material and SOI film as the film thickness decreased. The low field mobility increased with the depletion of the SOI film.When the SOI film was 500 Å thick, the mobility exceeded that of a bulk MOS device fabricated with the same doping concentration. The current overshoot during switching in the thin‐film SOI device was too small to o

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730409

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper studies an Nb/AlOxNb junction, and the cross‐sectional shape of the junction interface and the surface state are observed. It is found that the AlOxfilm used as the tunnel barrier layer is locally nonuniform and is dependent on the shape of the Nb film forming the lower electrode. This dependence is a factor causing junction characteristic variations. Further, the fabrication method of the Nb electrode film is discussed. It is important to form a flat and dense Nb film with few particle boundary trenches when fabricating the lower electrode film. A high‐quality Nb/AlOx/Nb film can be fabricated withRj/Rnn>20 and a fluctuation ofImoof ±6%. Also, the Nb/AlOx/Nb junction of 1.5 μm2with improved junction characteristics is applied to a 3 k logic gate array. The delay time of the 826‐stage OR gate is found to be 10.5

ISSN:8756-663X    

DOI:10.1002/ecjb.4420730410

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

年代:1990

数据来源: WILEY