In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction effi...In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.展开更多
The steady-state gain distribution in cladding pumped thulium-doped fiber laser(TDFL) is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With ...The steady-state gain distribution in cladding pumped thulium-doped fiber laser(TDFL) is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With the gain curve, a problem, which is named optical feedback inhibition(OFI) and always occurs in tandem TDFL-Ho:YAG laser system, is analyzed quantitatively. The actual characteristics of output spectra and power basically prove the conclusion of theoretical analysis. Then a simple mirror-deflected L-shaped cavity is employed to restrain the external feedback and simplify the structure of fiber-bulk Ho:YAG laser. Finally, 25 W of 2097-nm laser power and 51.2% of optical-to-optical conversion efficiency are obtained, and the beam quality factor is less than 1.43 obtained by knife-edge method.展开更多
Fluoride-based thulium-doped visible light fiber amplifier(TmVLFA), which can be used to amplify the blue light signal for a visible light communication(VLC) system,is theoretically demonstrated for the first time acc...Fluoride-based thulium-doped visible light fiber amplifier(TmVLFA), which can be used to amplify the blue light signal for a visible light communication(VLC) system,is theoretically demonstrated for the first time according to the best of our knowledge. The transition rate equations and power propagation equations are solved to predict the dependence of the gain and noise figure on fiber parameters. The numerical results show that with the pump wavelength 1150 nm and pump power 800 mW, 2.75 m long thulium-doped fiber can amplify blue light(480 nm) signal up to 33.3 dB, and the noise figure is in the range from 3.0 to 3.5 dB. The model and numerical results encourage the use of fiber amplifier in VLC system for blue light amplification to extend the range of VLC.展开更多
A comprehensive numerical model based on solving rate equations of a thulium-doped silica-based fiber amplifier is evaluated. The pump power and thulium-doped fiber (TDF) length for single-pass Thulium-Doped Fiber Amp...A comprehensive numerical model based on solving rate equations of a thulium-doped silica-based fiber amplifier is evaluated. The pump power and thulium-doped fiber (TDF) length for single-pass Thulium-Doped Fiber Amplifiers (TDFA) are theoretically optimized to achieve the optimum Gain and Noise Figure (NF) at the center of S-band region. The 1064 nm pump is used to provide both ground-state and excited state absorptions for amplification in the S-band region. The theoretical result is in agreement with the published experimental result.展开更多
It is crucial to study the effect of radiation on the fiber amplifier devices. In the present paper, the Erbium-ytterbium co-doped fiber amplifier (EYDFA) has been irradiated by a neutron beam of different doses for v...It is crucial to study the effect of radiation on the fiber amplifier devices. In the present paper, the Erbium-ytterbium co-doped fiber amplifier (EYDFA) has been irradiated by a neutron beam of different doses for various exposure times from an Am-241/Be-9 neutron source. The gain and noise figure of the EYDFA have been calculated theoretically and recorded after and before the irradiation to test its performance under the effect of irradiation. In order to show the enhancement in the gain of the fiber amplifier devices, a comparison between the gain of the irradiated EYDFA and Erbium doped Fiber amplifier (EDFA) has been carried out. The calculated results by the proposed model are in good agreement with the experimental ones. It indicates that the gain of EYDFA deteriorates after being irradiated by a neutron dose. Moreover, the gain of irradiated EYDFA has been reduced to 13.8 dB at a dose of 720 Gy.展开更多
Presented is a theoretical study of double-clad Er-doped fiber power amplifier(EDFA). Two kinds of double clad fibers(DCF) with rectangular and "flower" inner clad shapes are studied, and these fibers have d...Presented is a theoretical study of double-clad Er-doped fiber power amplifier(EDFA). Two kinds of double clad fibers(DCF) with rectangular and "flower" inner clad shapes are studied, and these fibers have different coupling constants and propagation losses. We calculate the effective pump power absorption ratio along the fiber with different coupling constants from the first cladding to the doped core and with different propagation losses for the power in the inner cladding. Then the gains of the double clad Er-doped fiber amplifiers versus fiber lengths are calculated using the EDFA model based on propagation and rate equations of a homogeneous, two-level medium.展开更多
Through the introduction of the overlapping factors between the light (pump and signal) intensities and the erbium doping distributions inside the fiber core, analytical solutions of homogeneously broadened two-level ...Through the introduction of the overlapping factors between the light (pump and signal) intensities and the erbium doping distributions inside the fiber core, analytical solutions of homogeneously broadened two-level systems for erbium-doped fiber amplifiers pumped in the 980 nm absorption band have been derived from EDFA rate equations and light propagation equations in steady-state case. By using these deduced expressions and numerical simulated methods, important features characterizing the amplifiers such as gain, pump threshold power, optimum fiber length have been analyzed and discussed.展开更多
Optical channel pre-emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s wavelength division multiplexing (WDM) transmission system with three Erbium-doped fiber amplifiers (ED- FAs)...Optical channel pre-emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s wavelength division multiplexing (WDM) transmission system with three Erbium-doped fiber amplifiers (ED- FAs) and Raman amplifiers concatenated as booster amplifier. The channel imbalance of the overall system changes with different sets of power launched into EDFAs. By appropriately choosing the power input to concatenated EDFAs, the output spectrum of 40 channel signal can be equalized to the most extent. The merit of benefit can be around 5.5 dB by this pre-emphasis equalization. The requirement for the gain equalizer is therefore greatly released. Then the gain imbalance of the overall system and the power imbalance of 40 channels are compared and the two almost matches, but the significant difference lies on some channels. Finally, the pump power into Raman amplifier is also optimized, and another 1.3 dB improvement of channel equaliza- tion can be further achieved.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 60878011 and 61078008)the Program for New Century ExcellentTalents in University,China (Grant No. NCET-10-0067)
文摘In this paper, the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region. The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.
基金Project supported by the National Natural Science Foundation of China(Grant No.61275146)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120002110066)the Special Program of the Co-construction with Beijing Municipal Government of China(Grant No.20121000302)
文摘The steady-state gain distribution in cladding pumped thulium-doped fiber laser(TDFL) is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With the gain curve, a problem, which is named optical feedback inhibition(OFI) and always occurs in tandem TDFL-Ho:YAG laser system, is analyzed quantitatively. The actual characteristics of output spectra and power basically prove the conclusion of theoretical analysis. Then a simple mirror-deflected L-shaped cavity is employed to restrain the external feedback and simplify the structure of fiber-bulk Ho:YAG laser. Finally, 25 W of 2097-nm laser power and 51.2% of optical-to-optical conversion efficiency are obtained, and the beam quality factor is less than 1.43 obtained by knife-edge method.
文摘Fluoride-based thulium-doped visible light fiber amplifier(TmVLFA), which can be used to amplify the blue light signal for a visible light communication(VLC) system,is theoretically demonstrated for the first time according to the best of our knowledge. The transition rate equations and power propagation equations are solved to predict the dependence of the gain and noise figure on fiber parameters. The numerical results show that with the pump wavelength 1150 nm and pump power 800 mW, 2.75 m long thulium-doped fiber can amplify blue light(480 nm) signal up to 33.3 dB, and the noise figure is in the range from 3.0 to 3.5 dB. The model and numerical results encourage the use of fiber amplifier in VLC system for blue light amplification to extend the range of VLC.
文摘A comprehensive numerical model based on solving rate equations of a thulium-doped silica-based fiber amplifier is evaluated. The pump power and thulium-doped fiber (TDF) length for single-pass Thulium-Doped Fiber Amplifiers (TDFA) are theoretically optimized to achieve the optimum Gain and Noise Figure (NF) at the center of S-band region. The 1064 nm pump is used to provide both ground-state and excited state absorptions for amplification in the S-band region. The theoretical result is in agreement with the published experimental result.
文摘It is crucial to study the effect of radiation on the fiber amplifier devices. In the present paper, the Erbium-ytterbium co-doped fiber amplifier (EYDFA) has been irradiated by a neutron beam of different doses for various exposure times from an Am-241/Be-9 neutron source. The gain and noise figure of the EYDFA have been calculated theoretically and recorded after and before the irradiation to test its performance under the effect of irradiation. In order to show the enhancement in the gain of the fiber amplifier devices, a comparison between the gain of the irradiated EYDFA and Erbium doped Fiber amplifier (EDFA) has been carried out. The calculated results by the proposed model are in good agreement with the experimental ones. It indicates that the gain of EYDFA deteriorates after being irradiated by a neutron dose. Moreover, the gain of irradiated EYDFA has been reduced to 13.8 dB at a dose of 720 Gy.
基金Foundation of Beijing Jiaotong University(2005RC034)
文摘Presented is a theoretical study of double-clad Er-doped fiber power amplifier(EDFA). Two kinds of double clad fibers(DCF) with rectangular and "flower" inner clad shapes are studied, and these fibers have different coupling constants and propagation losses. We calculate the effective pump power absorption ratio along the fiber with different coupling constants from the first cladding to the doped core and with different propagation losses for the power in the inner cladding. Then the gains of the double clad Er-doped fiber amplifiers versus fiber lengths are calculated using the EDFA model based on propagation and rate equations of a homogeneous, two-level medium.
基金Project supported by the Chinese Academy of Sciences
文摘Through the introduction of the overlapping factors between the light (pump and signal) intensities and the erbium doping distributions inside the fiber core, analytical solutions of homogeneously broadened two-level systems for erbium-doped fiber amplifiers pumped in the 980 nm absorption band have been derived from EDFA rate equations and light propagation equations in steady-state case. By using these deduced expressions and numerical simulated methods, important features characterizing the amplifiers such as gain, pump threshold power, optimum fiber length have been analyzed and discussed.
基金the National Natural Science Foundation of China (60777024)
文摘Optical channel pre-emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s wavelength division multiplexing (WDM) transmission system with three Erbium-doped fiber amplifiers (ED- FAs) and Raman amplifiers concatenated as booster amplifier. The channel imbalance of the overall system changes with different sets of power launched into EDFAs. By appropriately choosing the power input to concatenated EDFAs, the output spectrum of 40 channel signal can be equalized to the most extent. The merit of benefit can be around 5.5 dB by this pre-emphasis equalization. The requirement for the gain equalizer is therefore greatly released. Then the gain imbalance of the overall system and the power imbalance of 40 channels are compared and the two almost matches, but the significant difference lies on some channels. Finally, the pump power into Raman amplifier is also optimized, and another 1.3 dB improvement of channel equaliza- tion can be further achieved.
文摘报道了一种利用频率为几千赫兹的高频 CO2激光脉冲的热冲击效应制作长周期光纤光栅的新技术。实验中,作者首次发现这种新型的长周期光纤光栅具有一些独特的光学特性,比如弯曲特性和横向负载特性等,这主要是因为用高频 CO2激光脉冲写成的长周期光纤光栅的横截面折射率分布不对称所致。基于这种新型长周期光纤光栅,设计了一种用于减小掺铒光纤放大器噪声系数的 ASE 噪声滤波器和平坦掺铒光纤放大器增益谱的增益均衡器,此外,还利用这种新型长周期光纤光栅独特的弯曲和压力特性,研究设计了两种用于动态平坦掺铒光纤放大器增益谱的动态增益均衡器。