KEYWORDS: Advanced distributed simulations, Internet, Telecommunications, Databases, Televisions, Mobile communications, Global Positioning System, General packet radio service, Phase modulation, Lithium
As advertisements are time and location sensitive, a challenge for wireless marketing is to have advertisements delivered when and where they are most convenient. In this paper we introduce a two-stage auction model for location-based wireless targeted advertising. This system extends the notion of location-based service by using location information to target advertising, and does so specifically by enabling advertisers to specify their preferences and bid for advertisement delivery, where those preferences are then used in a subsequent automated auction of actual deliveries to wireless data users. The automated auction in the second stage is especially effective because it can use information about the individual user profile data, including customer relationship management system contents as well as location from the wireless system's location management service, including potentially location history such as current trajectory from recent history and longer-term historical trip records for that user. Through two-stage auction, real-time bidding by advertisers and matching ads contents to mobile users help advertising information reach maximal value.
High power single-mode AlGaAs semiconductor lasers operating between 820 nm and 860 nm (SDL-5400 series diodes) have been successfully qualified for deployment in many free-space inter-satellite communication link programs. Traditionally these high power devices did not have sufficient bandwidth for direct high speed modulation because of large device and package parasitics. We have improved the device parasitics of the SDL-5430 laser diode, i.e. reduced the RC product, from 240 ps to about 40 ps. The initial measurements indicate that this device (SDL-5480) is suitable for high power optical inter-satellite link (OISL) applications at data rates greater than 1 Gbit/s. The preliminary life test indicates that the new device has better a reliability than the previous design.
High power multi-mode semiconductor lasers operating between 1 Watt and 2 Watts are widely used for pumping solid-state lasers, active fibers and direct materials processing. In this paper, we present the high power and high temperature performance characteristics of 100 micrometer aperture broad area lasers. In addition, we will present lifetest data that supports mean lifetimes in excess of 500,000 hours for this class of lasers. 1
High power diode lasers are important for a variety of applications including diode-pumped (DP) solid state lasers, DP fiber lasers/amplifiers and a variety of printing and medical applications. Recently, there have been significant advances in the maximum cw powers achieved from both multimode and singlemode lasers in both AlGaAs-based and InGaAsP- based materials. The highest powers from broad area lasers have been achieved with high quality AlGaAs-based materials. For example, cw powers of 11.3 and 16.5 W have been demonstrated at 870 nm from 100 and 200 micrometers wide apertures, respectively. These power levels correspond to a facet loading of 80-110 mW/micrometers and facet power densities of 27 MW/cm2 which are approximately 2-fold higher than previously reported results. In this paper we report on the performance, reliability and degradation characteristics of AlGaAs- based lasers.
We present a 10 channel parallel fiber optic link consisting of a transmitter based on an edge emitting laser diode array operating at 980 nm and a complementary receiver based on an InGaAs pin photodetector array. We demonstrate link performance up to data rates of 1 Gbit/s with measurement time limited bit errors rates lower than 10-11 over 100 m of multi-mode fiber ribbon cable.
We review data on the high temperature operation of a high speed data link operating at 1 micrometer wavelength. The single mode fiber packaged transmitter consists of an 'uncooled' high speed laser diode packaged with a commercial laser driver chip and operates at data rates up to 1.2 Gbit/s. The single mode fiber packaged receiver consists of a high speed photodiode packaged with a combination of a commercial transimpedance amplifier and a limiting amplifier. The link operates with high stability and very low error rates without an optical isolator. The maximum data rate and the minimum link sensitivity are currently limited by the electronic component design.
We present data on the wide temperature operation of a high speed data link operating at nominally 1 micrometer wavelength. The single mode fiber packaged transmitter running at 1.2 GBit/s consists of a high speed laser diode packaged with a commercial laser driver chip. The laser is not cooled in any manner over the temperature range of operation and the link operates with low error rates without an optical isolator. The single mode fiber packaged receiver consists of a high speed photodiode packaged with a combination of a commercial transimpedance amplifier and a limiting amplifier.
The SDL-5400 series commercial AlGaAs laser diode was characterized and screened for potential use as communication laser in the SILEX program. The lasers were initially tested through environmental extremes and for vacuum reliability to obtain preliminary indications that the laser was suitable to the requirement. Potential flight lasers were then built and screened for use. Endurance testing of samples from the potential flight lot has been completed.
Long duration life tests of approximately 6,000 hours on AlGaAs single-mode lasers operating at 200 mW and 50 degree(s)C indicate that high reliability can be obtained under these conditions. The projected median life is 140,000 hr and MTBF is 100,000 hr. These results compare favorably with data from other material systems.
The reliability of continuously operating (cw) high power laser arrays is a critical factor for the acceptance of these devices in a wide range of applications. Extensive investigation into the reliability of semiconductor lasers has led to an improved understanding of failure mechanisms such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure. Furthermore, as a result of material quality improvements, laser arrays exhibit very low gradual degradation for high power operation up to 2 Watts cw. Long term lifetest data shows that the projected medium life at room temperature of such devices exceed 100,000 hours at 2 W cw.
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