The present invention includes a memory subsystem comprising at least two semiconductor devices (15, 16 , 17), including at least one memory device (15, 16 or 17), connected to a bus (18), where the bus includes a plurality of bus lines for carrying substantially all address, data and control information needed by said memory devices (15, 16 or 17), where the control information includes device-select information and the bus (18) has substantially fewer bus lines than the number of bits in a single address, and the bus (18) carries device-select information without the need for separated device-select lines connected directly to individual devices. The present invention also includes a protocol for master and slave devices to communicate on the bus (18) and for registers in each device to differentiate each device and allow bus requests to be directed to a single or to all devices (15, 16, 17). The present invention includes modifications to prior-art devices to allow them to implement the new features of this invention. In a preferred implementation, 8 bus data lines and an Address Valid bus line carry address, data and control information for memory addresses up to 40 bits wide.

Integrated circuit I/O using a high performance bus interface

A fiber for optical transmission composed of a core having a substantially parabolic distribution of refractive index, a first cladding layer formed around the core having a refractive index equal to that of the periphery of the core and a thickness of 1/100 to 1/20 the diameter of the core, a second cladding layer formed around the first cladding layer having a refractive index smaller than that of the first cladding layer, and a third cladding layer formed around the second cladding layer having a refractive index greater than that of the second cladding layer. The fiber for optical transmission having such a structure has a broad bandwidth of transmitted light.

Fiber for optical transmission

This paper presents a theoretical investigation on the dispersion in graded-index silica glass fibers under overfilled launching with equal excitation of modes. This theory incorporates both chromatic effect and modal contribution which takes not only the modal delay into account but also the distributed loss and mode-coupling. Random microbends are considered to be the most dominant source of coupling. All index perturbations and intrinsic core diameter variations are assumed to be negligible, but they could readily be included without changing the basic structure of the model. The 3-dB bandwidth is analyzed through the study of the fiber transfer function which introduces the wavelength and modal effects as two separate filter functions. The formal derivation of the chromatic transfer function is analytical. On the other hand, the modal transfer function is obtained by numerically solving the power flow equation in the frequency domain using Crank-Nicholson method. As an application, the results are illustrated showing, in particular, the influence of the fiber core/outside diameters, for the first time.

/pdf/comprehensive-theory-of-dispersion-in-graded-index-optical-15ic5vlwey.pdf

Comprehensive theory of dispersion in graded-index optical fibers

Over the past two decades, fiber laser technologies have matured to such an extent that they have captured a large portion of the commercial laser marketplace. Yet, there still is a seemingly unquenchable thirst for ever greater optical power to levels where certain deleterious light-matter interactions that limit continued power scaling become significant. In the past decade or so, the industry has focused mainly on waveguide engineering to overcome many of these hurdles. However, there is an emerging body of work emphasizing the enabling role of the material. In an effort to underpin these developments, this paper reviews the relevance of the material in high power fiber laser technologies. As the durable material-of-choice for the application, the discussion will mainly be limited to silicate host glasses. The discussion presented herein follows an outward path, starting with the trivalent rare earth ions and their spectroscopic properties. The ion then is placed into a host, whose impact on the spectroscopy is reviewed. Finally, adverse interactions between the laser lightwave and the host are discussed, and novel composition glass fiber design and fabrication methodologies are presented. With deference to the symbiosis required between material and waveguide engineering in active fiber development, this review will emphasize the former. Specifically, where appropriate, materials-based paths to the enhancement of laser performance will be underscored.

/pdf/materials-for-optical-fiber-lasers-a-review-2n45z3gaeq.pdf

Materials for optical fiber lasers: A review

Disclosed is an optical waveguide fiber having a core surrounded by a layer of cladding material The core is characterized in that it includes a region of depressed refractive index The inner radius a i of this region is greater than zero, and the outer radius a o thereof is less than the core radius By appropriately selecting the core index depression characteristics such as radial location, width, depth and shape, a fiber having the desired waveguide dispersion characteristics can be designed Dispersion minimization over a wide wavelength range can be achieved, without adverse effect on system loss

Low dispersion, low-loss single-mode optical waveguide

A high-speed ring LAN capable of accommodating at least one public network having a signal transmission rate of 15557 MHz, and at least one sub-LAN having a signal transmission rate of 100 MHz The high-speed LAN has a signal transmission rate of 15552 Mbps ×n (n is an even number) SONET (Synchronous Optical NETwork) subframes each comprising a 9 bytes ×9 section overhead area and a 261 bytes ×9 virtual container 4 (VC-4) area flow in a time-divisional n-multiplexed format The respective node devices inserted in the transmission path have one or more ports to accommodate sub-LANs or public networks Information is exchanged in units of a fixed-length packet between a received SONET subframe and an asynchronous port whereas information is exchanged in units of a byte between the SONET subframe and a synchronous port

High-speed ring lan system

An optical coupling system between a semiconductor laser and an optical fiber is disclosed. The system is characterized in that a medium having a refractive index greater than 1 but smaller than the refractive index of the semiconductor laser material is packed between the end surface of a distributed feedback type or distributed Bragg reflector type semiconductor laser and the end surface of an optical fiber.

Optical coupling system with intermediate coupling medium

The microbending of optical fibers causes some additional transmission losses. In this paper, the theoretical and experimental results on the microbending characteristics for doubly clad (W-type) fibers are described. A simple approximation in which W-type fibers are considered as equivalent singly clad fibers is employed to calculate the additional losses due to microbending. It is shown that the additional losses of W-type fibers depend on the optical wavelength. Further, it is shown that the structural imperfections of the guide can be also considered a kind of microbending which affects the spectral loss characteristics of W-type fibers.

Microbending losses of doubly clad (W-type) optical fibers.

The steady-state characteristics of multimode W-type fibers are investigated by solving the coupled-power equation numerically. It is shown that the steady-state power distributions depend on both the intermediate layer width and the coupling strength. Unlike singly clad fibers, the steady-state loss (coupling-induced loss) in W-type fibers is not proportional to the coupling strength. The loss in W-type fibers varies between the value for two types of singly clad reference fibers as the coupling strength changes.

Steady-state characteristics of multimode W-type fibers

Transmission characteristics of multimode step-index W-type optical fibers are theoretically investigated by numerically solving the complex power flow equations. Spatial transients of power distribution and power level, as well as transmission length dependence of transmission bandwidth, are calculated for the mode-coupling condition from guided to lossy leaky modes, a characteristic of W-type fibers. The transmission characteristics of W-type fibers change from those of two singly clad reference fibers when the width of the intermediate layer is changed. The trade-off relation between the bandwidth and steady-state loss is also discussed.

Toshiki P. Tanaka

Papers

High-speed ring lan system

Optical coupling system with intermediate coupling medium

Microbending losses of doubly clad (W-type) optical fibers.

Steady-state characteristics of multimode W-type fibers

Numerical solution of power flow in multimode W-type optical fibers.