Telcordia Technologies

About: Telcordia Technologies is a based out in . It is known for research contribution in the topics: Network packet & Node (networking). The organization has 3097 authors who have published 4737 publications receiving 237882 citations.

Linking system and method for accessing directory information about an object in one context when information in another context is known

Abstract: Our linking method is implemented in our linking system which includes an interconnection network, which employs a standard directory protocol, such as X.500, and linking components. The interconnection network includes interfaces for interconnection users and local directories. The linking components include linking directories and linking applications which are connected to the interconnection network via interfaces. Linking directories contain entries, and each entry comprises linking references pointing to entities, which include local directories and linking applications and have access to information about the object in different contexts. In the linking directory, there is an entry for each object, and this entry is accessible using a linking identifier unique the object. The linking application coordinates a response to the user's request and sends queries to the linking directory, local directories, and other linking application to fulfill user's requests. A user can access requested information by inputting known information about an object in one context along with a request for information about the object in another context. The known information is used by the linking application to query a local directory in the network for the linking identifier corresponding to the object. The linking application then uses the linking identifier to query the linking directory for linking references pointing entities having further access to information about the object in the specified context. The linking application uses the linking reference to locate the entities pointed to and the linking identifier as a key to retrieve the requested information. This retrieved information is formatted by the linking application and forwarded to the user in response to the request.

Wideband digital equalizers for subscriber loops

Abstract: A digital decision feedback equalizer is disclosed in which compensation for the post-cursors of the impulse response of the transmission channel is divided up into two regions. A first region encompasses the initial rapidly changing unpredictable transient response, possibly oscillatory, of the transmission channel. A fast acting, close-tracking linear filter is used to compensate for this largely unpredictable initial transient. The second region of the impulse response is the slowly changing, easily predictable asymptotic tail of the impulse response. This second region can be compensated for by a relatively slowacting, simple pole-zero filter. Together, the two equalizer sections provide anoverall equalizer design far less complicated and less expensive than an equalizer based on a single linear compensating filter. A finite impulse response (FIR) filter is used to compensate for the unpredictable, rapidly changing initial transient portion of the impulse response, while an infinite impulse response (IIR) filter is used to compensate for the slower acting tail portion of the impulse response.

Mode locking of semiconductor diode lasers using saturable excitonic nonlinearities

Abstract: Multiple-quantum-well (MQW) structures of GaAs and GaAlAs have been used for passive mode locking of commercial GaAs semiconductor diode lasers. We present an extended discussion of this application of the sensitive room-temperature excitonic absorption saturation in MQW material. We review the criteria for passive mode locking and discuss two methods—carrier diffusion and proton bombardment—for reducing the aborption recovery time without destroying the excitonic nonlinearity. A simple probabilistic theory is derived for the effect of bombardment on the excitonic effects that is in order-of-magnitude agreement with experiment. We have performed experiments using MQW material to mode lock a GaAs laser. A continuous train of pulses as narrow as 1.6 psec has been obtained with a pulse-repetition rate of 2 GHz.

Efficient power coupling from a 980-nm, broad-area laser to a single-mode fiber using a wedge-shaped fiber endface

Abstract: A theoretical and experimental study of an efficient technique for coupling a broad-area laser to a single-mode fiber without the use of bulk optical components was carried out. The technique uses a wedge-shaped fiber endface to approximate a cylindrical lens action to correct for the phase mismatch between the curved laser beam wavefront and the planar fiber beam. A theoretical formula for the coupling efficiency in the absence of both angular and transverse misalignments is derived. By optimizing the wedge angle and the axial separation between the laser facet and the fiber endface, a maximum coupling efficiency of 47%, compared to 20% for the square endface, achieved, resulting in 15.2 mW of power in the single-mode fiber. The fabrication process consists of a simple polishing procedure requiring a wedge-shaped polishing tool and is highly reproducible. >

A class of self-healing ring architectures for SONET network applications

Abstract: Synchronous optical network (SONET) technology has made high-speed self-healing ring (SHR) architectures practical and economical. The SHR architectures can be divided into two basic classes: bidirectional SHR (B-SHR) and unidirectional SHR (U-SHR). The cost and capacity tradeoffs between B-SHRs and U-SHRs depend strongly on the application, the network size, and the demand pattern. B-SHRs with four fibers can be operated under today's operations environment without a significant change. However, U-SHRs using a path protection switching method may ease intervendor compatibility problems and can be implemented on a timely basis without changing the well-defined SONET APS protocol. The selection of appropriate SONET SHR architectures will depend on the operating telephone companies' economic analysis, emphasis on a multivendor environment, SHR implementation time frame, and standards progress on making change to support a bidirectional ring architecture. >