Long wavelength quantum well lasers: Synopsis of the RACE “AQUA” project: MOVPE/MBE/GSMBE for InGaAsP/InP and InGaAlAs/InP high speed MQW DFB lasers

The technological limits for ultra high speed devices are now rapidly expanding due to the use of quantum well (QW) materials. This new class of materials gives the opportunity of tailoring materials parameters by controlling geometries on an atomic scale. They look very promising as materials for lasers, detectors and transistors suitable even above 10 Gb/s. It will be demonstrated that state of the art MQW structures can be realized in both material systems, InGaAsP/InP and InGaAlAs/InP. Parallel lateral laser structures (e.g. SIBH, BRS and TBH) have been designed to take full benefit of QW technology. Ultimate reduction of parasitics, whilst using potential low cost fabrication technologies is the basis for achieving high bitrate (10 Gb/s) MQW lasers, even with the stronger damping in QW material. Using the DFB-SIBH laser structure 10 Gb/s large signal experiments are successfully performed with bulk, MQW and SLMQW lasers. Extremely low fall times of 44 ps are achieved. Additional MQW based improvements are observed such as: −3 times higher differential gain, increased output power (>110 mW), 2.5 times lower chirp (Δλ_−20dB = 0.40 nm at 10 Gb/s modulation), and 2 dB gain in power budget at 10 Gb/s digital transmission.     

IPDI在聚氨酯反应中对选择性温度、催化过程和反应对象的影响

在一项针对异佛尔酮二异氰酸酯（IPDI）于氨基甲酸酯反应中的选择性之模型研究中，提示了催化剂类型和温度的影响，同时通过选择伯丁醇和仲丁醇作为反应对象，介绍了羟基类型的影响。需特别指出的是，催化剂的选择对最终产品的组成有着极重大的影响。模型研究的最重要续集在NCO预聚物的合成中得到了肯定。     

Bemessung von Grundbauwerken aus Stahlbeton nach DIN 1054 (01.03)

Design of Foundation Construction made of Reinforced Concrete according to DIN 1054 (01.03) Other than the idea given in DIN 1054 (draft november 1976) the scope of the revised draft of january 2003 clearly also refers to the stability as well as the serviceability of construction and structural members concerning ground and foundation work. However, the design concepts proposed in this contribution, do not completely correspond to other regulations of the new “Generation of Standards”, in particular to the rules for the design of concrete structural members (DIN 1045‐1, part 1‐4, DIN 1055‐100, DIN Fachberichte 100‐104). This leads to interpretation possibilities for the interface between both standards. In the following the main features and differences of both standards are introduced and application rules are proposed. Furthermore, the application of the new “Generation of Standards” is presented within the example of a tunnel structure in mining construction. These results are compared to the results according to the standards which have been valid so far (DIN 1045 (07.88), DIN 1054 (11.76), ZTV‐Tunnel part I).     

Einsatz von GFK‐Bewehrung bei der Ausführung des U‐Bahnhofs Brandenburger Tor

Using FRP reinforcement in construction of the metroline station Brandenburger Tor. At present the metroline station Brandenburger Tor in Berlin is under construction. The station is to be one of the three stations for the provisional shuttle service between Lehrter Bahnhof, Reichstag and Brandenburger Tor. The shuttle service will be in service in the year 2007. As a first step of construction an excavation pit using diaphragm walls is erected where the platform area will be built using conventional mining excavation with ground freezing. In order to establish the ground freezing 30 microtunnels with a diameter of 1.60m have to be driven which will be supplied with frozen lines. For the first time in Germany glass fiber reinforced polymers (FRP) are employed for the extremely stressed diaphragm walls which form the micro tunnels. Because of the low transverse strength the FRP can separated easily.