为提高光载无线(radio over fiber,RoF)传输系统中的光波信号的利用率,本文提出了一种基于两个平行马赫-增德尔调制器(Mach-Zehnder modulator,MZM)的RoF传输系统。两个平行MZM经射频(radio frequency,RF)信号调制后,产生5个光边带信号...为提高光载无线(radio over fiber,RoF)传输系统中的光波信号的利用率,本文提出了一种基于两个平行马赫-增德尔调制器(Mach-Zehnder modulator,MZM)的RoF传输系统。两个平行MZM经射频(radio frequency,RF)信号调制后,产生5个光边带信号,分别是正负一阶光边带、正负二阶光边带和光载波。其中正负二阶光边带使用基带数据进行调制,经光电检测器(photodiode,PD)拍频后产生已调数据的毫米波信号,再由天线发射出去。正二阶边带和光载波经PD拍频后产生未调制数据的毫米波,该毫米波用于接收端解调的本振信号(local oscillator,LO)。负二阶边带信号用于上行链路的光载波。在本系统中,5个光边带信号都被充分利用,提高了光信号的利用效率。此外,还分析了该系统通过色散介质的传输特性,为RoF通信系统提供了一种实用化的解决方案。展开更多
A kind of erbium doped photosensitive fiber(EDPF) was proposed and fabricated,whose core was made of double layers named photosensitive layer and erbium doped layer.The double-layer core de-sign can overcome difficult...A kind of erbium doped photosensitive fiber(EDPF) was proposed and fabricated,whose core was made of double layers named photosensitive layer and erbium doped layer.The double-layer core de-sign can overcome difficulties in fabrication of EDPF with single core design,i.e.the conflict between the high consistency rare earth doping and high consistency germanium doping.A sample was fabri-cated through the modified chemical vapor deposition method combined with solution doping tech-nique.The peak absorption coefficient was 48.80 dB/m at 1.53 μm,the background loss was lower than 0.1 dB/m,and the reflectivity of the fiber Brag gratings(FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology.Moreover,a C band tunable fiber laser was fabricated using the sample fiber,in which a uniform FBG was written directly on EDPFs as a reflector.A single wavelength lasing with a maximum wavelength tuning range of 1555.2―1558.0 nm was achieved experimentally.Within this tuning range,the full-width at half maximum(FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio(SMSR) was better than 50 dB.展开更多
An optimal refractive index profile of pure silica core optical fiber (PSCF) was de- signed, in combination with the characters of the modified chemical vapor deposi- tion (MCVD) process. Techniques of preform fabrica...An optimal refractive index profile of pure silica core optical fiber (PSCF) was de- signed, in combination with the characters of the modified chemical vapor deposi- tion (MCVD) process. Techniques of preform fabrication by a new furnace round heating MCVD process and fiber drawing process were reviewed. Difficulties in doping fluorine in silica, widening the depressed-index cladding and maintaining the index of fiber core were discussed. Methods used to overcome these difficulties were given at the same time. Additionally, the optimal refractive index profiles of PSCF were presented.展开更多
For the PANDA ring-core polarization-maintaining few-mode fiber(RC-PM-FMF)with the given supported eigenmodes,the minimum effective refractive index difference min(Δneff)between the adjacent eigenmodes decreases with...For the PANDA ring-core polarization-maintaining few-mode fiber(RC-PM-FMF)with the given supported eigenmodes,the minimum effective refractive index difference min(Δneff)between the adjacent eigenmodes decreases with the RC size.Consequently,we propose a PANDA RC-PM-FMF assisted by a ring-sector(RS)structure,which can be used to mainly increase theΔneff values between the adjacent even and odd eigenmodes with the same polarization.The RS-RC-PM-FMF with an appropriate choice of the parameters can support 10 linearly polarized(LP)eigenmodes,which have min(Δneff)values higher than 1.9×10^(-4) for the adjacent eigenmodes over the whole C+L band.Furthermore,the fiber is characterized by the low group velocity dispersion(GVD)(-40—20 ps·nm^(-1)·km^(-1))and effective mode areas(63—104μm^(2)),while the total losses are within the range of 0.19—0.23 d B/km over the whole band.展开更多
基金Supported by the National High Technology Research and Development Program of China (863 Project) (Grant No. 2007AA01Z258)the National Natural Science Foundation of China (Grant No. 60771008)+2 种基金Program for New Century Excellent Talents in University (Grant No. NCET-06-0076)Beijing Natural Science Founda-tion (Grant No. 4052023)the Beijing Jiaotong University Foundation (Grant No. 2006XM003)
文摘A kind of erbium doped photosensitive fiber(EDPF) was proposed and fabricated,whose core was made of double layers named photosensitive layer and erbium doped layer.The double-layer core de-sign can overcome difficulties in fabrication of EDPF with single core design,i.e.the conflict between the high consistency rare earth doping and high consistency germanium doping.A sample was fabri-cated through the modified chemical vapor deposition method combined with solution doping tech-nique.The peak absorption coefficient was 48.80 dB/m at 1.53 μm,the background loss was lower than 0.1 dB/m,and the reflectivity of the fiber Brag gratings(FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology.Moreover,a C band tunable fiber laser was fabricated using the sample fiber,in which a uniform FBG was written directly on EDPFs as a reflector.A single wavelength lasing with a maximum wavelength tuning range of 1555.2―1558.0 nm was achieved experimentally.Within this tuning range,the full-width at half maximum(FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio(SMSR) was better than 50 dB.
基金the Hi-Tech Research and Development Program of China (Grant No. 2002AA312190)National Natural Science Foundation of China (Grant No. 60477017)+2 种基金Program for the New Century Excellent Talents in University (Grant No. NCET-06-0076)Beijing Natural Science Foun-dation (Grant No. 4052023)the Beijing Jiaotong University Foundation (Grant No. 2006XM003)
文摘An optimal refractive index profile of pure silica core optical fiber (PSCF) was de- signed, in combination with the characters of the modified chemical vapor deposi- tion (MCVD) process. Techniques of preform fabrication by a new furnace round heating MCVD process and fiber drawing process were reviewed. Difficulties in doping fluorine in silica, widening the depressed-index cladding and maintaining the index of fiber core were discussed. Methods used to overcome these difficulties were given at the same time. Additionally, the optimal refractive index profiles of PSCF were presented.
基金supported by the National Key Research and Development Program of China(No.2018YFB1801003)the National Natural Science Foundation of China(No.61575018)。
文摘For the PANDA ring-core polarization-maintaining few-mode fiber(RC-PM-FMF)with the given supported eigenmodes,the minimum effective refractive index difference min(Δneff)between the adjacent eigenmodes decreases with the RC size.Consequently,we propose a PANDA RC-PM-FMF assisted by a ring-sector(RS)structure,which can be used to mainly increase theΔneff values between the adjacent even and odd eigenmodes with the same polarization.The RS-RC-PM-FMF with an appropriate choice of the parameters can support 10 linearly polarized(LP)eigenmodes,which have min(Δneff)values higher than 1.9×10^(-4) for the adjacent eigenmodes over the whole C+L band.Furthermore,the fiber is characterized by the low group velocity dispersion(GVD)(-40—20 ps·nm^(-1)·km^(-1))and effective mode areas(63—104μm^(2)),while the total losses are within the range of 0.19—0.23 d B/km over the whole band.
