A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained....A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained. Then, a single-mode DBR fiber laser of 7.9cm long with master oscillator power amplifier (MOPA) configuration is designed and constructed to operate in the single-mode domain. The fiber laser is pumped by a semiconductor laser at 975.5nm. The master oscillator operates at 1556.91 nm with a cw output power of 1.43mW for a pump power of 55.35 mW. Its slope efficiency is 2.7% and the spectral linewidth is less than 1.2MHz (instrument resolution limited). With the MOPA configuration the laser output power and slope efficiency are increased to 7.8mW and 16.9%, respectively.展开更多
We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber grat...We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber gratings can be controlled by simply varying the tension applied. Both the theory and experimental results are presented.展开更多
An electrically tunable optical fibre Macli-Zehnder interferometer is reported,based on the magnetostrictive effect.The period and peak wavelength of the interference spectrum can be electrically tuned to match the In...An electrically tunable optical fibre Macli-Zehnder interferometer is reported,based on the magnetostrictive effect.The period and peak wavelength of the interference spectrum can be electrically tuned to match the International Telecommunication Union standard wavelength grid and so it is promising to be used in dense wavelength division multiplexing technology.展开更多
Hydrogen loading provides highly enhanced photosensitivity in Ge-doped fiber. But the Bragg wavelength of UV-written fiber grating will shift from its initial value as the remaining hydrogen diffuses out of such fiber...Hydrogen loading provides highly enhanced photosensitivity in Ge-doped fiber. But the Bragg wavelength of UV-written fiber grating will shift from its initial value as the remaining hydrogen diffuses out of such fiber. A simple model to calculate the index change of hydrogenated fibers is presented. The theoretical model is in good agreement with experimental results and it can well predict the final wavelength position of UV-written weak fiber grating.展开更多
Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommu-nication fiber and photosensitive fiber.The index changes due to ultraviolet exposure were found to be closel...Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommu-nication fiber and photosensitive fiber.The index changes due to ultraviolet exposure were found to be closely related with the OH formation in both types of fibers.A direct photolyticd model is proposed to explain the effect of hydrogen loading on the enhancement of the photosensitivity in silica fibers.展开更多
The increase of absorption loss in photosensitivity enhanced optical fiber via H_(2) loading induced in the making process of fiber grating was measured.From the results it can be seen that hydroxyl induced by exposin...The increase of absorption loss in photosensitivity enhanced optical fiber via H_(2) loading induced in the making process of fiber grating was measured.From the results it can be seen that hydroxyl induced by exposing the H_(2) loaded GeO_(2)-doped optical fiber to 248nm light causes large absorption loss at 1.4μm.A reaction model is postulated to describe the process that leads to the loss increase and photosensitivity enhancement in GeO_(2)-doped optical fiber.展开更多
Thais luteostoma has been utilized as a crude drug whose shell and soft tissue have been widely used for the treatment of heat syndrome in China for thousands of years. The present study was designed to investigate th...Thais luteostoma has been utilized as a crude drug whose shell and soft tissue have been widely used for the treatment of heat syndrome in China for thousands of years. The present study was designed to investigate the antipyretic and anti-inflammatory activities of T. luteostoma. T. luteostoma was divided into shell （TLSH） and soft tissue （TLST） samples in the present study. The rat model of yeast-induced fever was used to investigate their antipyretic effects; and the rat model of hind paw edema induced by carrageenan was utilized to study their anti-inflammatory activities, and at the same time, the concentration variations of the central neurotransmitter [prostaglandin E2 （PGE2） and cyclic adenosine monophosphate （cAMP）], inflammatory mediators [tumor necrosis factor （TNFα）, interleukin-1β （IL-1）, interleukin-2 （IL-2） and interleukin-6 （IL-6）] and ion （Na^＋ and Ca^2＋） were also tested. The results showed that TLSH and TLST extracts significantly inhibited yeast-induced pyrexia in rats （P 〈 0.05）, and exhibited more lasting effects as compared to aspirin, and TLSH had the better antipyretic activity than TLST, and that TLSH and TLST could significantly prevent against carrageenan induced paw edema in rats （P 〈 0.05）; and markedly reduced levels of PGE2, cAMP, TNFα, IL-1β, IL-2, IL-6, and Na^＋/Ca^2＋. In fever model, TLST could significantly reduce the levels of PGE2 （P 〈 0.01） in rats＇ homogenate and TNF a （P 〈 0.05）, IL-113 （P 〈 0.01） in the plasma than TLSH, whereas TLSH could reduce the content of IL-2 （P 〈 0.01） and IL-6 （P 〈 0.01） in plasma and increase the content of Ca2＋ （P 〈 0.01） in plasma and homogenate more significantly than TLST. In conclusion, T. luteostoma extract has antipyretie and anti-inflammatory activities, which may be mediated through the suppression of production of PGE2, cAMP, Na^＋/Ca^2＋ , TNF a, IL-1β, IL-2, and IL-6.展开更多
基金Supported by Doctoral Program Foundation of Institution of Higher Education under Grant No.9600106the NationalNatural Science Foundation of China under Grant No.69637050.
文摘A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained. Then, a single-mode DBR fiber laser of 7.9cm long with master oscillator power amplifier (MOPA) configuration is designed and constructed to operate in the single-mode domain. The fiber laser is pumped by a semiconductor laser at 975.5nm. The master oscillator operates at 1556.91 nm with a cw output power of 1.43mW for a pump power of 55.35 mW. Its slope efficiency is 2.7% and the spectral linewidth is less than 1.2MHz (instrument resolution limited). With the MOPA configuration the laser output power and slope efficiency are increased to 7.8mW and 16.9%, respectively.
基金the National Natural Science Foundation of China under Grant Nos.69777008 and 69637050.
文摘We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber gratings can be controlled by simply varying the tension applied. Both the theory and experimental results are presented.
基金Supported by the National Natural Science Foundation of China under Grant Nos.69777008 and 69637050.
文摘An electrically tunable optical fibre Macli-Zehnder interferometer is reported,based on the magnetostrictive effect.The period and peak wavelength of the interference spectrum can be electrically tuned to match the International Telecommunication Union standard wavelength grid and so it is promising to be used in dense wavelength division multiplexing technology.
基金Supported by the National Natural Science Foundation of China under Grant Nos.69777008 and 69637050.
文摘Hydrogen loading provides highly enhanced photosensitivity in Ge-doped fiber. But the Bragg wavelength of UV-written fiber grating will shift from its initial value as the remaining hydrogen diffuses out of such fiber. A simple model to calculate the index change of hydrogenated fibers is presented. The theoretical model is in good agreement with experimental results and it can well predict the final wavelength position of UV-written weak fiber grating.
基金Supported by the National Natural Science Foundation of China under Grant No.69637050。
文摘Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommu-nication fiber and photosensitive fiber.The index changes due to ultraviolet exposure were found to be closely related with the OH formation in both types of fibers.A direct photolyticd model is proposed to explain the effect of hydrogen loading on the enhancement of the photosensitivity in silica fibers.
基金Supported by the National Natural Science Foundation of China under Grant No.69377012.
文摘The increase of absorption loss in photosensitivity enhanced optical fiber via H_(2) loading induced in the making process of fiber grating was measured.From the results it can be seen that hydroxyl induced by exposing the H_(2) loaded GeO_(2)-doped optical fiber to 248nm light causes large absorption loss at 1.4μm.A reaction model is postulated to describe the process that leads to the loss increase and photosensitivity enhancement in GeO_(2)-doped optical fiber.
基金supported by Marine Industry Research Special Funds for Public Welfare Projects(201205024–1)The Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(ysxk-2010)
文摘Thais luteostoma has been utilized as a crude drug whose shell and soft tissue have been widely used for the treatment of heat syndrome in China for thousands of years. The present study was designed to investigate the antipyretic and anti-inflammatory activities of T. luteostoma. T. luteostoma was divided into shell （TLSH） and soft tissue （TLST） samples in the present study. The rat model of yeast-induced fever was used to investigate their antipyretic effects; and the rat model of hind paw edema induced by carrageenan was utilized to study their anti-inflammatory activities, and at the same time, the concentration variations of the central neurotransmitter [prostaglandin E2 （PGE2） and cyclic adenosine monophosphate （cAMP）], inflammatory mediators [tumor necrosis factor （TNFα）, interleukin-1β （IL-1）, interleukin-2 （IL-2） and interleukin-6 （IL-6）] and ion （Na^＋ and Ca^2＋） were also tested. The results showed that TLSH and TLST extracts significantly inhibited yeast-induced pyrexia in rats （P 〈 0.05）, and exhibited more lasting effects as compared to aspirin, and TLSH had the better antipyretic activity than TLST, and that TLSH and TLST could significantly prevent against carrageenan induced paw edema in rats （P 〈 0.05）; and markedly reduced levels of PGE2, cAMP, TNFα, IL-1β, IL-2, IL-6, and Na^＋/Ca^2＋. In fever model, TLST could significantly reduce the levels of PGE2 （P 〈 0.01） in rats＇ homogenate and TNF a （P 〈 0.05）, IL-113 （P 〈 0.01） in the plasma than TLSH, whereas TLSH could reduce the content of IL-2 （P 〈 0.01） and IL-6 （P 〈 0.01） in plasma and increase the content of Ca2＋ （P 〈 0.01） in plasma and homogenate more significantly than TLST. In conclusion, T. luteostoma extract has antipyretie and anti-inflammatory activities, which may be mediated through the suppression of production of PGE2, cAMP, Na^＋/Ca^2＋ , TNF a, IL-1β, IL-2, and IL-6.
