Abstract:The principle and structure of Er/Yb doped glass integrated optical waveguide amplifiers are presented, along with the fabrication process. Recent progress and future development are also described.

Abstract:Aerial images cover wide areas and include huge information. By knowing the fators affecting the quality of images, then evaluating the image quality aimly, the redundant information can be reduced and the processing speed can be optimized. Furthermore, there are no references for many aerial images and it is feasible to evaluate image quality only by knowing the cause of degrading image quality. Main factors affecting image quality are analyzed and concluded, and the way to evaluate aerial image quality is provided.

Abstract:在室温下测量了GaAs／Al0.28Ga0.72As超晶格的光致发光，发现在波长λ=764nm处存在一较强的发光峰。理论分析表明，此峰是量子阱阱口附近能级上的电子与受主杂质上的空穴复合发光。实验还观测到在λ=824nm和829nm处分别存在一发光峰。分析表明，λ=829nm和λ=824mn处的发光峰分别为激子发光和量子阱中基态电子与基态重空穴的复合发光；理论计算值与实验结果符合得很好。

Abstract:Because of the features of low cost and low power consumption, infrared wireless local area networks which use infrared ray as the transmission medium for short range indoor wireless communication have been used widely. In this paper, the infrared medium access control layer protocol and some problems concerned are analyzed. The formulas for calculating the normalized throughput of infrared wireless local area networks are deduced and the content window size and its adjustment method are studied. On the basis of above work, the performance of the medium access control is optimized and a new infrared adaptive medium access algorithm which can overcome the shortcomings of existing IrWLANs is proposed. The optimized infrared adaptive access performance is verified by using the OPNET Modeler package.

Abstract:The laser detection of underwater acoustic signals exploited a laser receiving technique. It uses light wave in air and uses acoustic wave under water. Because two best channels are combined together, it is an ideal method for remotely detecting underwater acoustic signals. The underwater acoustic signal can cause surface wave motion at waterair interface and modulate the magnitude of the laser beam falling on tile water surface. The modulated underwater laser signal can be detected by using a direct light intensity detecting method. In this paper, the feasibility of the laser detection of underwater acoustic signals is verified experimentally on the basis of theoretical analysis and some problems to be solved are discussed.