基于MMI滤波器的可调谐连续光全光纤OPO

在连续光全光纤光学参量振荡器（FOPO）中,目前主要利用可调滤波器（TBPF）等高插入损耗的滤波器件进行边带光输出波长的调谐,这种方式所引起的高环形腔损耗限制了FOPO输出性能的进一步提升。为解决此问题,提出了基于多模干涉（MMI）滤波器的低腔损耗可调谐连续光FOPO。通过选取不同长度和纤芯尺寸的多模光纤制作级联单模-多模-单模光纤（SMS）作为滤波器件,使其在选定波长处的插入损耗小于1 dB,FOPO环形腔的总损耗不大于5 dB,并通过对SMS器件施加轴向拉力的方式调节滤波器件的透射谱,实现了1 494~1 501 nm和1 638~1 629 nm范围内的双边带可调谐连续光输出。     

基于应变的多模光纤可调谐光纤滤波器设计

可调谐光纤滤波器技术是波分复用系统的关键技术之一,对于发展全光通信网络和光纤传感具有极其重要的意义。提出了一种基于大芯径的多模光纤可调谐带阻滤波器,其制作方法是将包层/纤芯直径为125/105μm的特种多模光纤通过单模光纤接入光纤系统,实现单模-多模-单模(SMS)光纤结构,并使一端单模光纤与多模光纤熔接,另一端只是共轴对接而不焊接。在多模干涉原理的基础上,利用该结构对应变的敏感性实现可调谐光滤波。该可调谐滤波器的调制和解调借助于放大自发辐射(ASE)宽谱光源和光谱分析仪(OSA)实现。详细给出了该滤波器的理论仿真分析,并实验证实了该方案的有效性。     

复合滤波结构的窄线宽高频微波信号产生装置

为了在较低泵浦功率下实现单纵模双波长激光信号的输出,进而获得窄线宽的高频微波信号,设计并实验了一种基于复合滤波结构的窄线宽高频微波信号产生装置。通过8字腔结构布里渊增益腔和反射式光纤光栅构成的波长选择滤波器实现了4倍布里渊频移间隔的双波长斯托克斯光信号输出,采用200 m长单模光纤作为增益介质,同时与50 m长单模光纤构成级联光纤环结构,采用三端口耦合器与2 m长未泵浦的保偏掺铒光纤构成萨格纳克环结构,利用级联光纤环结构和萨格纳克环结构的复合滤波作用实现了斯托克斯光信号模式的选择,使输出的斯托克斯光信号由多纵模运行状态变为单纵模运行状态。实验证明:通过对输出的单纵模双波长斯托克斯光信号进行拍频检测可得42.85 GHz的高频微波信号产生,线宽为38 kHz;通过改变可调谐泵浦激光器的输出波长,可实现42.25~43.51 GHz范围内的频率调谐;通过稳定性测试,产生的42.85 GHz高频微波信号的频率变化在0.83 MHz内,峰值功率变化在±0.8 dB内,稳定性良好,满足实际应用需求。     

基于高双折射光纤环镜的可调谐光滤波器

为了得到具有全光纤结构和中心波长可调谐的光滤波器,采用3阶高双折射光纤环镜,提出了一种电磁力的悬臂调谐单元构成的新型可调谐光滤波器,对环镜传输过程和悬臂调谐单元原理进行了理论分析,通过控制悬臂调谐单元的输入电流,实现了滤波器通带的调谐。结果表明,该滤波器具有调谐灵活、输出光谱精细等特点,可应用于不同波长光波的选频输出。     

基于高双折射光纤环镜的可调谐光滤波器

为了得到具有全光纤结构和中心波长可调谐的光滤波器,采用3阶高双折射光纤环镜,提出了一种电磁力的悬臂调谐单元构成的新型可调谐光滤波器,对环镜传输过程和悬臂调谐单元原理进行了理论分析,通过控制悬臂调谐单元的输入电流,实现了滤波器通带的调谐。结果表明,该滤波器具有调谐灵活、输出光谱精细等特点,可应用于不同波长光波的选频输出。     

基于单通带微波光子滤波的多倍频微波信号产生

理论分析和实验验证了一种多倍频微波信号的光学产生方法。基于大信号相位调制和单模光纤的色散效应产生多个多倍频谐波,通过引入一个中心频率连续可调的单通带微波光子滤波器,实现了对单个倍频微波信号的提取。调节宽带光源的谱分割间隔可实现倍频微波信号调谐输出。在理论分析的基础上搭建了实验系统,利用5GHz低频驱动信号得到了10GHz和15GHz的微波信号,其10dB线宽为几十赫兹,功率波动为1dB～2dB。     

小型圆形贴片谐振器宽带带通滤波器设计

提出了一种频率在3.1~6.5GHz范围内的新型小型宽带带通滤波器。该滤波器结合圆形贴片谐振器的多模特性,通过引入输入端和输出端之间的耦合,增加了传输零点。通过三维仿真软件Ansoft HFSS中建模并优化,实现了通带内抑制在-20dB以下,低频段在1.9GHz处产生一个传输零点,高频段在7.6GHz处产生一个传输零点,带外抑制在-20dB以下。实测滤波器的结果与仿真结果基本一致,验证了设计的有效性。     

基于多波长光纤激光器和色散器件级联的微波光子带通滤波器

提出了一种基于多波长光纤激光器和色散器件级联的微波光子带通滤波器。该滤波器利用双折射光纤环镜对多波长激光器的输出信号进行整形,整形后的信号作为滤波器的抽头,实现滤波器的可重构性。将标准单模光纤(SSMF)和光纤延迟环级联作为延迟单元,实现滤波器的频率选择性。通过改变波长间隔或标准单模光纤的长度,实现滤波器的可调谐性。研究结果表明与只用SSMF作延迟单元相比,该微波光子滤波器的品质因数Q提高了182.26,3dB带宽减小了670MHz。     

基于双光源的可调谐微波光子滤波器

提出了一种基于双光源与双相移光纤光栅(DPS- FBG)的可调谐微波光子滤波器。双光源经过相 位调制后,利用DPS-FBG的反射模式中的两超窄陷波分别对两相位调制光信号的边带进行抑 制,实现相 位调制至强度调制的转换。通过调节两光源的中心波长可以实现单通带与双通带之间的切换 ,实现单通带 的中心频率可调以及3dB带宽可调,实现双通带频率同时可调或者单独可调。建立了理论模 型并进行了数 值分析,最后通过实验进行了验证。实现了滤波器通带的3dB带宽由180MHz增加为319MHz,中心频率从1GHz到7GHz可调。     

全新布里渊散射可切换微波光子滤波器

提出了一个新的基于布里渊散射效应的微波光子滤波器。该滤波器可通过调谐系统中光滤波器的中心波长,实现高解析度带通滤波器与陷波滤波器之间的灵活切换,并且通过调谐产生受激布里渊散射的泵浦光的波长可实现滤波器通带或阻带的中心频率在很大频率范围内连续调谐。该滤波器为全光结构,因此具有非常大的调谐范围（调谐上限仅受限于试验中使用的矢量网络分析仪的显示频率上限）。系统中采用相位调制器,因此没有偏置电压漂移问题。实验结果展示了一个带通与陷波滤可灵活切换的高解析度微波光子滤波器,并且通带和阻带的中心频率在9～26.5 GHz范围内连续可调谐,其中带通滤波器的通带具有极窄3 dB带宽,约28 MHz（由光纤本身布里渊增益区线宽所决定）。     

Tunable self-seeded multi-wavelength Brillouin-erbium fiber laser based on few-mode fiber filter

A tunable self-seeded multi-wavelength Brillouin-erbium fiber laser (BEFL) is proposed and demonstrated based on a few-mode fiber filter (FMFF) with varying temperature. The FMFF configuration is a section of uncoated few-mode fiber (FMF) sandwiched between two up-tapers. As the temperature varies from 25 °C to 125 °C, the transmission spectrum of FMFF moves towards the longer wavelength. The self-excited Brillouin pump is internally achieved by cascaded stimulated Brillouin scattering (SBS) in the single mode fiber (SMF). Then employing the FMFF temperature variation characteristics in the ring cavity fiber laser, the multi-wavelength of the output laser can be tuned, and the tunable range is about 8.0 nm. The generation of up to 15 Brillouin Stokes wavelengths with 16 dB optical signal-to-noise ratio (OSNR) is realized.     

A stable optical comb with double-Brillouin-frequency spacing assisted by multiple four-wave mixing processes

A stable optical comb with a double-Brillouin-frequency spacing, employing a 2.5-km common single mode fiber (SMF) is proposed and demonstrated experimentally. The simultaneous existence of the first-order and third-order Stokes within the ring cavity excites the higher-order Stokes and anti-Stokes via multiple four-wave mixing (FWM) processes. Ten odd-order Stokes, nine odd-order anti-Stokes and a second-order Stokes signal with a wavelength spacing of 0.172 nm (∼20 GHz) are simultaneously achieved at a Brillouin pump (BP) level of 160 mW. The maximum power fluctuation of the proposed optical comb is less than 1 dB at room temperature within 100 min. The optical comb can show a good stability and flexibility in the choice of operating wavelength.     

基于多模光纤偏振烧孔效应的双波长掺铒光纤激光器

基于多模光纤(MMF)引入的偏振烧孔(PHB)效应,研制了一种环形双波长掺铒光纤(EDF)激光器.单模光纤(SMF)-MMF-SMF组成的结构使MMF不同偏振方向的反射模在波长上分开,利用PHB效应实现双波长的输出,输出波长间隔可通过改变MMF的长度改变.实验对比了1.6 m和3.0 m长的MMF输出波谱特性,结果表明...     

具有32 GHz频差的掺Yb3+双频DBR光纤激光器

基于自制的双波长低反射率光纤光栅（FBG）作为分布式布拉格反射激光器（DBR）的输出端,实现了掺Yb3+双频DBR光纤激光器。该FBG的双波长间隔为0.12 nm,对应的频差为32 GHz。双频光纤激光器输出的两个波长分别为1 063.09 nm和1 063.21 nm,光谱信噪比大于60 dB。每一个波长只包含一个纵模。两个纵模的拍频信号为32.014 GHz,频谱信噪比大于35 dB。得益于光纤激光器本身具有结构紧凑,抗干扰能力强等特点,该型激光器有望作为高品质,小型化的微波信号源,用于微波传感和通信等领域。     

Acoustooptic Tunable Gap-Type Bandpass Filter With a Broad Stopband

We demonstrate a novel all-fiber gap-type tunable bandpass filter configuration that consists of a broadband hollow optical fiber (HOF) acoustooptic tunable filter (AOTF) concatenated with a narrowband single-mode fiber (SMF)-AOTF. Owing to the unique mode coupling properties of HOF-AOTF and SMF-AOTF, a narrow passband channel of a full-width at half-maximum (FWHM) of ~4 nm could be formed in a broad stopband platform of a 90-nm FWHM successfully. In this scheme, the center wavelength and rejection efficiency of both passband and stopband were found to be flexibly tunable by adjusting the frequency and the voltage of radio-frequency signals applied to individual acoustic transducers.     

10-Gb/s Transmission on Single-Wavelength Multichannel SCM-Based FDDI-Grade MMF Links at Lengths Over 300 m: A Statistical Investigation

We propose and comprehensively investigate a subcarrier-multiplexing (SCM) system based on 62.5-mum-core-diameter multimode fiber (MMF) using a single wavelength to achieve 10-Gb/s transmission over link lengths beyond 300 m, using 1.3-mum-wavelength lasers with radial offset launch into MMF links. The system utilizes multichannel SCM transmission using quadrature-phase-shift-keyed modulation in combining baseband transmission with three passband SCM channels at the carrier frequencies of 3.75, 6.25, and 8.75 GHz while incorporating a maximum laser modulation bandwidth of 10 GHz to ensure system compliance with the limits of current uncooled laser devices. A statistical investigation of the system highlights its capability to achieve an acceptable yield over worst-case MMF links of length 600 m. We also investigate the improvement in system performance granted by allowing a controlled overlap of frequency spectra of the passband SCM channels. In addition, we test the accuracy of the previously proposed usable average slope criterion of less than 4 dB/GHz, which is needed to achieve low-penalty transmission with eye-closure penalties <3 dB.     

Research on optical fiber magnetic field sensors based on multi-mode fiber and spherical structure

A magnetic field sensor with a magnetic fluid (MF)-coated intermodal interferometer is proposed and experimentally demonstrated. The interferometer is formed by sandwiching a segment of single mode fiber (SMF) between a segment of multi-mode fiber (MMF) and a spherical structure. It can be considered as a cascade of the traditional SMF-MMF-SMF structure and MMF-SMF-sphere structure. The transmission spectral characteristics change with the variation of applied magnetic field. The experimental results exhibit that the magnetic field sensitivities for wavelength and transmission loss are 0.047 nm/mT and 0.215 dB/mT for the interference dip around 1 535.36 nm. For the interference dip around 1548.41nm, the sensitivities are 0.077 nm/mT and 0.243 dB/mT. Simultaneous measurement can be realized according to the different spectral responses.     

MEMS可调式光衰减器性能测试及其分析

采用微细加工的方法研制出了一种可调式微机械光衰减器 ,对该衰减器的性能进行了测试 ,并对影响其光学性能的因素作了分析。测试表明 ,该衰减器的插入损耗<3dB ,衰减范围 0～ 4 0dB ,回波损耗 <- 45dB ,衰减精度可达 0 1dB。     

Wavelength add-drop switching using tilting micromirrors

This paper describes a single-mode optical fiber switch which routes individual signals into and out of a wavelength multiplexed data stream without interrupting the remaining channels. The switch uses free-space optical wavelength multiplexing and a column of micromechanical tilt-mirrors to switch 16 channels at 200 GHz spacing from 1531 to 1556 nm. The electrostatically actuated tilt mirrors use an 80 V peak-to-peak 300 KHz sinusoidal drive signal to switch between ±10° with a 20 μs response. The total fiber-to-fiber insertion loss for the packaged switch is 5 dB for the passed signals and 8 dB for added and dropped signals, with 0.2 dB polarization dependence. Switching contrast was 30 dB or more for all 16 channels and all input and output states. We demonstrate operation by switching 622 Mb/s data on eight wavelength channels between the two input and output ports with negligible eye closure