In this letter,a theoretical model of radiation-balanced double clad fiber laser is presented.The characteristic of the laser with Yb doped double clad fiber is analyzed numerically.It is concluded that high output la...In this letter,a theoretical model of radiation-balanced double clad fiber laser is presented.The characteristic of the laser with Yb doped double clad fiber is analyzed numerically.It is concluded that high output laser power can be obtained by selecting output coupling mirror with lower reflectivity,improving Yb doped concentration and choosing fiber length. This result can help us to design radiation balanced fiber laser.展开更多
It is predicted theoretically that a one-dimensional photonic crystal(PC)with a defect layer has an incident-angle dependent transmittance.Growing a multilayer of this PC structure on a BK7 glass substrate by means of...It is predicted theoretically that a one-dimensional photonic crystal(PC)with a defect layer has an incident-angle dependent transmittance.Growing a multilayer of this PC structure on a BK7 glass substrate by means of thermal vacuum evaporation,we have experimentally measured its transmittance at near-infrared wavelength.The measured transmittance are in good agreement with the theoretical prediction if the influence of random errors in the layer thicknesses resulting from the deposition process is excluded.This work suggests that a one-dimensional PC with a defect layer can be fabricated as a two-dimensional near-field low-pass spatial filter.展开更多
For representation based image classification methods, it is very important to well represent the target image. As pixels at same positions of training samples and test samples of an object usually have different inte...For representation based image classification methods, it is very important to well represent the target image. As pixels at same positions of training samples and test samples of an object usually have different intensities, it brings difficulty in correctly classifying the object. In this paper, we proposed a novel method to reduce the effects of this issue for image classification. Our method first produces a new representation （i.e. virtual image） of original image, which can enhance the importance of moderate pixel intensities and reduce the effects of larger or smaller pixel intensities. Then virtual images and corresponding original images are respectively used to represent a test sample and obtain two rep- resentation results. Finally, this method fuses these two results to classify the test sample. The integration of original image and its virtual image is able to improve the accuracy of image classification. The experiments of image classification show that the proposed method can obtain a higher accuracy than the conventional classification methods.展开更多
基金This project was supported by Foundation of China Academy ofEngineering Physics under Grant NO.2004R0205 .
文摘In this letter,a theoretical model of radiation-balanced double clad fiber laser is presented.The characteristic of the laser with Yb doped double clad fiber is analyzed numerically.It is concluded that high output laser power can be obtained by selecting output coupling mirror with lower reflectivity,improving Yb doped concentration and choosing fiber length. This result can help us to design radiation balanced fiber laser.
基金the National Basic Research Program of China under Grant No 2012CB315701the National Natural Science Foundation of China under Grant Nos 61025024 and 11076011the Natural Science Foundation of Hunan Province under Grant No 12JJ7005.
文摘It is predicted theoretically that a one-dimensional photonic crystal(PC)with a defect layer has an incident-angle dependent transmittance.Growing a multilayer of this PC structure on a BK7 glass substrate by means of thermal vacuum evaporation,we have experimentally measured its transmittance at near-infrared wavelength.The measured transmittance are in good agreement with the theoretical prediction if the influence of random errors in the layer thicknesses resulting from the deposition process is excluded.This work suggests that a one-dimensional PC with a defect layer can be fabricated as a two-dimensional near-field low-pass spatial filter.
文摘For representation based image classification methods, it is very important to well represent the target image. As pixels at same positions of training samples and test samples of an object usually have different intensities, it brings difficulty in correctly classifying the object. In this paper, we proposed a novel method to reduce the effects of this issue for image classification. Our method first produces a new representation （i.e. virtual image） of original image, which can enhance the importance of moderate pixel intensities and reduce the effects of larger or smaller pixel intensities. Then virtual images and corresponding original images are respectively used to represent a test sample and obtain two rep- resentation results. Finally, this method fuses these two results to classify the test sample. The integration of original image and its virtual image is able to improve the accuracy of image classification. The experiments of image classification show that the proposed method can obtain a higher accuracy than the conventional classification methods.
