Pub Date : 1973-07-08DOI: 10.1002/J.1538-7305.1973.TB01995.X
W. Schlosser
The properties of modes in a slab structure with gain in the center region and loss in the surrounding medium are investigated. The propagation constant and field distribution of the lowest-order modes are determined. The cutoff frequencies and propagation constants of the next-higher mode are given. Furthermore, the effect of a refractive index depression or increase in the center region is determined. The depression does not destroy the mode, as may be expected, but causes it to have a cutoff frequency. Comparison of these results to the experimental data shows that gain-induced modes play an important part in the lateral confinement in stripe-geometry GaAs lasers.
{"title":"Gain-induced modes in planar structures","authors":"W. Schlosser","doi":"10.1002/J.1538-7305.1973.TB01995.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01995.X","url":null,"abstract":"The properties of modes in a slab structure with gain in the center region and loss in the surrounding medium are investigated. The propagation constant and field distribution of the lowest-order modes are determined. The cutoff frequencies and propagation constants of the next-higher mode are given. Furthermore, the effect of a refractive index depression or increase in the center region is determined. The depression does not destroy the mode, as may be expected, but causes it to have a cutoff frequency. Comparison of these results to the experimental data shows that gain-induced modes play an important part in the lateral confinement in stripe-geometry GaAs lasers.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"1 1","pages":"887-905"},"PeriodicalIF":0.0,"publicationDate":"1973-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90562225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-07-08DOI: 10.1002/J.1538-7305.1973.TB01999.X
R. S. Krupp, L. Tomko
An array of shift registers that may operate in two orthogonal directions can be called a planar shifting array. This article shows how two basic building blocks, fashioned from planar shifting arrays, may be interconnected to form a time-division switching network of arbitrary size. The characteristics of magnetic bubble and charge-coupled devices are compatible with the concept of planar arrays, and it is in these emerging technologies that switching networks of planar shifting arrays may become practical.
{"title":"Switching networks of planar shifting arrays","authors":"R. S. Krupp, L. Tomko","doi":"10.1002/J.1538-7305.1973.TB01999.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01999.X","url":null,"abstract":"An array of shift registers that may operate in two orthogonal directions can be called a planar shifting array. This article shows how two basic building blocks, fashioned from planar shifting arrays, may be interconnected to form a time-division switching network of arbitrary size. The characteristics of magnetic bubble and charge-coupled devices are compatible with the concept of planar arrays, and it is in these emerging technologies that switching networks of planar shifting arrays may become practical.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"1 1","pages":"991-1007"},"PeriodicalIF":0.0,"publicationDate":"1973-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76704570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-07-08DOI: 10.1002/J.1538-7305.1973.TB01992.X
D. Marcuse
This paper presents a comprehensive theory of mode coupling in optical fibers with imperfections. The paper begins with the derivation of a general coupled wave theory based on the modes of the ideal fiber. The general theory is applied to a simplified description of guided and radiation modes of the fiber that is valid for small core-cladding index differences. The simplified theory results in expressions for the coupling coefficients that are nearly as simple as those of the slab waveguide. As an example, the theory is applied to the calculation of radiation losses caused by pure core diameter changes and by elliptical deformations of the fiber core.
{"title":"Coupled mode theory of round optical fibers","authors":"D. Marcuse","doi":"10.1002/J.1538-7305.1973.TB01992.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01992.X","url":null,"abstract":"This paper presents a comprehensive theory of mode coupling in optical fibers with imperfections. The paper begins with the derivation of a general coupled wave theory based on the modes of the ideal fiber. The general theory is applied to a simplified description of guided and radiation modes of the fiber that is valid for small core-cladding index differences. The simplified theory results in expressions for the coupling coefficients that are nearly as simple as those of the slab waveguide. As an example, the theory is applied to the calculation of radiation losses caused by pure core diameter changes and by elliptical deformations of the fiber core.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"451 1","pages":"817-842"},"PeriodicalIF":0.0,"publicationDate":"1973-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77043981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-07-08DOI: 10.1002/J.1538-7305.1973.TB02003.X
P. Henry
{"title":"Attenuation through the clear atmosphere at 30, 19, and 13 GHz for low elevation angles","authors":"P. Henry","doi":"10.1002/J.1538-7305.1973.TB02003.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02003.X","url":null,"abstract":"","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"52 1","pages":"1031-1035"},"PeriodicalIF":0.0,"publicationDate":"1973-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82039964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01984.X
J. McKenna, N. Schryer
A two-dimensional analysis of the potential in charge coupled devices is presented. It is assumed that there are no mobile minority carriers, that the plate separation is zero, and that the plate voltage does not vary with time. The depletion layer approximation is used to linearize the equations, which are then solved exactly with the use of Fourier series. Both surface and buried channel devices are analyzed. These solutions can typically be evaluated on a computer in less than a tenth of the time it takes to obtain a solution by the method of finite differences. The solutions obtained here provide an important tool for the designer of charge coupled devices. In addition to describing the method of obtaining the solutions, we evaluate them to show the effects of a number of different design parameters, and compare the cost of these solutions with the cost of obtaining finite difference solutions.
{"title":"The potential in a charge coupled device with no mobile minority carriers and zero plate separation","authors":"J. McKenna, N. Schryer","doi":"10.1002/J.1538-7305.1973.TB01984.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01984.X","url":null,"abstract":"A two-dimensional analysis of the potential in charge coupled devices is presented. It is assumed that there are no mobile minority carriers, that the plate separation is zero, and that the plate voltage does not vary with time. The depletion layer approximation is used to linearize the equations, which are then solved exactly with the use of Fourier series. Both surface and buried channel devices are analyzed. These solutions can typically be evaluated on a computer in less than a tenth of the time it takes to obtain a solution by the method of finite differences. The solutions obtained here provide an important tool for the designer of charge coupled devices. In addition to describing the method of obtaining the solutions, we evaluate them to show the effects of a number of different design parameters, and compare the cost of these solutions with the cost of obtaining finite difference solutions.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"34 1","pages":"669-696"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81619695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01986.X
S. Rice
Definite integrals of analytic functions can often be evaluated efficiently by the trapezoidal rule after a suitable transformation. Here the work of Moran1 and Schwartz2 along this line is extended. First the dependence of the error on the spacing is discussed, and then several types of transformations are described and applied to integrals of technical interest.
{"title":"Efficient evaluation of integrals of analytic functions by the trapezoidal rule","authors":"S. Rice","doi":"10.1002/J.1538-7305.1973.TB01986.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01986.X","url":null,"abstract":"Definite integrals of analytic functions can often be evaluated efficiently by the trapezoidal rule after a suitable transformation. Here the work of Moran1 and Schwartz2 along this line is extended. First the dependence of the error on the spacing is discussed, and then several types of transformations are described and applied to integrals of technical interest.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"41 1","pages":"707-722"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80369485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01985.X
V. Benes
A connecting network is called strictly nonblocking if no call is blocked in any state; it is nonblocking in the wide sense if there exists a rule for routing calls through the network so as to avoid all states in which calls are blocked, and yet still satisfy all demands for connection as they arise, without disturbing calls already present. Characterizations of both senses of nonblocking have been given in previous work, using simple metric and closure topologies defined on the set of states. We give new characterizations based on the natural map γ (·) that carries each state into the assignment it satisfies. This map is a semilattice homomorphism, such that γ (x) ∩ γ(y) ≧ γ (x ∩ y). It turns out that the case of equality in this inequality is very relevant to nonblocking performance. In particular, let a subset X of states be said to have the intersection property if for every x in X and every assignment a there exists y in X such that y realizes a (i.e., γ (y) = a) and γ(x ∩ y) = γ (x) ∩ γ (y). Then a network is nonblocking in the wide sense if and only if some subset of its states has the intersection property, and it is strictly nonblocking if and only if the entire set of states has the intersection property.
{"title":"Semilattice characterization of nonblocking networks","authors":"V. Benes","doi":"10.1002/J.1538-7305.1973.TB01985.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01985.X","url":null,"abstract":"A connecting network is called strictly nonblocking if no call is blocked in any state; it is nonblocking in the wide sense if there exists a rule for routing calls through the network so as to avoid all states in which calls are blocked, and yet still satisfy all demands for connection as they arise, without disturbing calls already present. Characterizations of both senses of nonblocking have been given in previous work, using simple metric and closure topologies defined on the set of states. We give new characterizations based on the natural map γ (·) that carries each state into the assignment it satisfies. This map is a semilattice homomorphism, such that γ (x) ∩ γ(y) ≧ γ (x ∩ y). It turns out that the case of equality in this inequality is very relevant to nonblocking performance. In particular, let a subset X of states be said to have the intersection property if for every x in X and every assignment a there exists y in X such that y realizes a (i.e., γ (y) = a) and γ(x ∩ y) = γ (x) ∩ γ (y). Then a network is nonblocking in the wide sense if and only if some subset of its states has the intersection property, and it is strictly nonblocking if and only if the entire set of states has the intersection property.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"59 1","pages":"697-706"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74218669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01982.X
A. J. Rainal
This paper describes a method for computing baseband distortion in analog FM communication systems; the method is based on recent theoretical work available in the literature. The input baseband signal is taken to be a zero-mean, stationary Gaussian process having an arbitrary power spectral density. A variety of graphical results are presented in order to demonstrate the utility of this method of computing FM distortion. It is shown that the often-used noise loading test does not necessarily represent a worst-case test.
{"title":"Computing distortion in analog FM communication systems","authors":"A. J. Rainal","doi":"10.1002/J.1538-7305.1973.TB01982.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01982.X","url":null,"abstract":"This paper describes a method for computing baseband distortion in analog FM communication systems; the method is based on recent theoretical work available in the literature. The input baseband signal is taken to be a zero-mean, stationary Gaussian process having an arbitrary power spectral density. A variety of graphical results are presented in order to demonstrate the utility of this method of computing FM distortion. It is shown that the often-used noise loading test does not necessarily represent a worst-case test.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"28 1","pages":"627-648"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88447055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01987.X
K. Mueller
A new approach to time-domain pulse shaping in digital sampled systems is described. The proposed method allows time-limited impulse responses with optimum specified energy distribution in the frequency domain to be generated. Additional constraints to guarantee zero intersymbol interference are easily taken into account. Nyquist-type pulses which have the maximum possible amount of their total energy concentrated below some given frequency are one particularly important application. An example of such an impulse response with only 6 percent excess bandwidth is presented which shows that 99.96 percent of the energy can be concentrated in the desired bandwidth with a pulse 16 baud intervals long that can be generated using a read-only memory (ROM) with only 256 bits of storage. This new class of signals can be used advantageously for waveform generation and processing in digital data systems.
{"title":"A new approach to optimum pulse shaping in sampled systems using time-domain filtering","authors":"K. Mueller","doi":"10.1002/J.1538-7305.1973.TB01987.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01987.X","url":null,"abstract":"A new approach to time-domain pulse shaping in digital sampled systems is described. The proposed method allows time-limited impulse responses with optimum specified energy distribution in the frequency domain to be generated. Additional constraints to guarantee zero intersymbol interference are easily taken into account. Nyquist-type pulses which have the maximum possible amount of their total energy concentrated below some given frequency are one particularly important application. An example of such an impulse response with only 6 percent excess bandwidth is presented which shows that 99.96 percent of the energy can be concentrated in the desired bandwidth with a pulse 16 baud intervals long that can be generated using a read-only memory (ROM) with only 256 bits of storage. This new class of signals can be used advantageously for waveform generation and processing in digital data systems.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"17 1","pages":"723-729"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79104260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01988.X
W. Hubbard
Recent advances in solid-state optical-frequency sources and detectors and low-loss optical fibers make feasible the consideration of optical communication systems for low- and moderate-bandwidth channels (a few kHz to, say, 100 MHz). This paper explores the use of optical-frequency carrier systems for transmission over such channels. Analog intensity modulation, pulse position modulation, delta modulation, and pulse code modulation are considered. This paper is intended to be tutorial in nature.
{"title":"Utilization of optical-frequency carriers for low- and moderate-bandwidth channels","authors":"W. Hubbard","doi":"10.1002/J.1538-7305.1973.TB01988.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01988.X","url":null,"abstract":"Recent advances in solid-state optical-frequency sources and detectors and low-loss optical fibers make feasible the consideration of optical communication systems for low- and moderate-bandwidth channels (a few kHz to, say, 100 MHz). This paper explores the use of optical-frequency carrier systems for transmission over such channels. Analog intensity modulation, pulse position modulation, delta modulation, and pulse code modulation are considered. This paper is intended to be tutorial in nature.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"32 1","pages":"731-765"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73583304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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