基于色散光纤环级联结构的可调谐带通微波光子滤波器

提出并验证了一种宽调谐带宽的带通微波光子滤波器设计方案。该滤波器借助可调谐光纤光栅Sagnac环对宽带光源进行均匀切割,产生波长间隔可调的连续光载波作为滤波器的抽头,结合色散光纤环级联结构,实现滤波器的可重构性。研究结果表明,在光电调制器和光电探测器的频率带宽足够大的情况下,当光纤光栅Sagnac环的臂长差在0.50~8.28mm内变化、可调谐光纤延迟线的最小变化步长为0.01mm时,该方案能够实现滤波器中心频率在8.0506~1333.2000GHz内调谐,调谐步长为161.01MHz,边瓣抑制比达到27dB。     

A variable coefficient microwave photonic filter based on multi-wavelength fiber laser and Mach-Zehnder interferometer

A microwave photonic filter（MPF） with variable coefficient is proposed and demonstrated, which is constructed by a multi-wavelength fiber laser and Mach-Zehnder interferometer（MZI）. Through changing the slope characteristics of Mach-Zehnder interference spectrum adjusted by optical variable delay line（OVDL）, the conversion from phase modulation（PM） to intensity modulation（IM） is realized. The multi-wavelength fiber laser with Lyot-Sagnac optical filter has variable wavelength spacing. So the designed filter has a variable number of taps and tap weights. As a result, the tunable range of passband center frequency is 2.6 GHz. The reconfigurability of MPF can be also realized by adjusting the output of fiber laser.     

Widely tunable wavelength spacing dual-wavelength single longitudinal mode erbium doped fiber laser

A simple widely tunable wavelength spacing dual-wavelength single longitudinal mode (SLM) erbium doped fiber laser (EDFL) based on cascaded fiber Bragg gratings (FBGs) and birefringent fiber filter is proposed and demonstrated. Experimental results show that the lasing wavelength spacing is widely tunable in a range from 2 nm to 18 nm, which has potential to generate frequency tunable terahertz (THz) waves by beating the lasing dual-wavelength in a high speed photodetector. The birefringent fiber filter acts as an ultra-narrow bandpass filter and benefits the simultaneous oscillation of dual-wavelength in a single laser cavity. The output peak power of the lasing dual-wavelength is approximately equalized at room temperature, and a high optical signal-to-noise ratio (OSNR) is realized in the whole tuning range. The SLM operation of dual-wavelength fiber laser is verified by Fabry–Perot (F–P) scanning interferometer, and the clear eye diagram proves that the proposed fiber laser is effective in the application of fiber optic communication system.     

MEMS可调谐平顶窄带光学滤波器

设计了一种基于MEMS技术的可调谐光学滤波器,它通过光栅将输入的宽带光信号色散展开,以一个MEMS扭镜选择将对应滤波器通带的光信号反射至输出端,从而实现光学滤波和波长调谐功能。滤波器的输入端采用单模光纤,输出端采用多模或者少模光纤,可以实现窄带且平顶的通带特性。经过参数优化,仿真分析得结果显示,采用多模/少摸光纤输出的两种滤波器,其0.5 dB和25 dB带宽分别为0.95 nm/0.29 nm和1.39 nm/0.69 nm,分别满足100 GHz和50 GHz信道间隔的DWDM系统要求。由于输出端采用多模或者少摸光纤,从该滤波器输出的光信号不能继续在单模光纤中传输,只能由光探测器接收,因此该滤波器一般应用于全光网络节点中的下载端口。     

Bragg grating fast tunable filter for wavelength divisionmultiplexing

A Bragg grating fast tunable filter prototype working over a linear tuning range of 45 nm with a maximum tuning speed of 21 nm/ms has been realized. The tunable filter system is based on two piezoelectric stack actuators moving a mechanical device thus compressing an apodized fiber Bragg grating. The filter allows both traction and compression and can work in transmission and in reflection. It is designed to work with a channel spacing of 100 GHz according to the ITU specifications for wavelength division multiplexing systems     

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）。     

基于近零介电常数超材料的液晶可调带通滤波器设计方法研究

可调带通滤波器是物联网、卫星通信、智能天线等系统中不可缺少的关键器件之一。针对目前对可调带通滤波器小型化、低成本和高集成度等特点的应用需求,提出了一种基于液晶材料的可调带通滤波器设计方法。通过微带传输线结构实现了近零介电常数(epsilon near zero,ENZ)超材料单元结构的设计,并利用ENZ超材料的窄通道隧穿效应有效实现了窄带滤波功能,通过将3个ENZ超材料单元结构串联从而完成了带通滤波器基本结构的设计。在此基础上,将微波液晶材料引入ENZ超材料的隧穿通道中,利用液晶材料在外部驱动电压作用下介电参数可变的特性,最终实现了对带通滤波特性的有效调控。全波数值仿真结果表明,所提出的基于ENZ超材料的液晶带通滤波器能够实现中心频率15.88~16.73 GHz的调控,从而验证了设计方法的有效性。     

基于Mach-Zehnder滤波的可调谐光纤激光器

() ()基金项目: 。摘要:为了实现高稳定性的可调谐激光输出,提出并设计了一种基于Mach-Zehnder(M-Z)滤波结构,结合Fabry-Perot(F-P)滤波器的可调谐掺铒光纤激光器,并对激光器的原理及实现方案进行理论分析和实验验证。所设计激光器系统的泵浦源工作波长为976 nm;长度5 m的掺铒光纤作为增益介质;采用全光纤M-Z结构进行滤波,并结合F-P滤波器实现单波长激光可调谐输出。实验中,通过调节F-P滤波器,在泵浦功率为60 mW时,实现了1547～1568 nm范围内单波长激光的稳定可调谐输出,波长调谐间隔小于1.7 nm,每个输出波长的边模抑制比均大于55 dB,线宽均小于0.1 nm。     

基于非线性色散补偿光栅的可调谐光电振荡器

为实现光电振荡器(OEO)输出频率的连续可调,提出一种新型的基于非线性色散补偿光栅(FBG)实现可调谐OEO方案。本文方案不需要电滤波器,且振荡频率随着光源的波长变化而变化。其中,三阶色散补偿FBG可以采用FBG重构算法设计。当光源波长从1 550.6nm变化到1 551.4nm时,相应的色散为340～1 460ps/nm,输出频率的调谐范围为6.5～13.5GHz,实现了振荡频率的大范围可调谐。     

Widely tunable chaotic fiber laser for WDM-PON detection

A widely tunable high precision chaotic fiber laser is proposed and experimentally demonstrated. A tunable fiber Bragg grating （TFBG） filter is used as a tuning element to determine the turning range from 1533 nm to 1558 nm with a linewidth of 0.5 nm at any wavelength. The wide tuning range is capable of supporting 32 wavelength-division mul- tiplexing （WDM） channels with 100 GHz channel spacing. All single wavelengths are found to be chaotic with 10 GHz bandwidth. The full width at half maximum （FWHM） of the chaotic correlation curve of the different wave- lengths is on a picosecond time scale, thereby offering millimeter spatial resolution in WDM detection.     

基于重构等效啁啾超结构光纤光栅的可调谐微波光子滤波器的仿真研究

提出了一种新型的基于重构等效啁啾(REC)超结构光纤光栅的可调谐微波光子滤波器的结构。根据REC技术, 利用同一块均匀相位掩模板可以灵活地设计制作出具有不同斜率的线性群时延的光纤光栅。作为有限冲击响应(FIR)滤波器的抽头延时单元, 不同光纤光栅之间群时延的差值决定了滤波器的自由频程(FSR)。通过改变可调谐激光器的输出波长来选择不同的抽头间时延差从而达到调谐FSR目的。仿真结果表明, 该滤波器可以实现中心频率从21 GHz到33 GHz的连续可调。事实上, 由于REC技术的灵活性, 在理论上对于任意给定的频段和调谐范围, 这种新型的滤波器结构都能够实现。     

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.     

All-optical filter for simultaneous implementation of microwave bandpass and notch responses based on semiconductor optical amplifier

An all-optical filter structure to simultaneously implement microwave bandpass and notch filter is proposed and experimentally demonstrated. The structure is based on a recirculating delay line (RDL) loop consisting of a semiconductor optical amplifier (SOA) followed by a tunable narrowband optical filter and a 10:90 coupler. The converted signal is generated in a wavelength conversion process based on cross-gain modulation of amplified spontaneous emission in the SOA. The converted signal circulating in RDL loop realizes a negative bandpass response. The negative bandpass filter and a broadband allpass filter are synthesized to achieve a notch filter with flat passband which can excise interference with minimal impact on the wanted signal.     

Flexibly tunable microwave photonic FIR filter incorporating wavelength spacing programmable, arrayed micro-mirror based optical filter

A novel tunable microwave photonic FIR filter incorporating a wavelength spacing tunable multiwavelength filter based on a programmable arrayed micro-mirror device (AMMD) is demonstrated. Owing to the unique characteristic of the AMMD, that an arbitrary optical filter shape can be produced by defining a desired spatial pattern on an array of /spl sim/800 000 micro-mirrors, a wavelength spacing tunable multiwavelength optical filtering pattern is readily obtainable. By controlling the optical filter wavelength spacing, flexible resonance RF frequency tuning is achieved over a range of 2.3 GHz.     

一种基于TFF的50GHz平顶型可调谐光滤波器

文章介绍了一种基于薄膜滤光片(TFF)技术的50 GHz通道间隔、平顶型可调谐光滤波器(TOF)的研制.对角度调谐干涉滤光片的原理进行了讨论,同时对超窄带膜系设计进行了优化.研制出的器件样品经过全面测试,实现了40 nm波长范围内96个ITU-T通道的可选择下路,为智能化的光网络提供了一种低成本、高性能的动态波长选择方案.     

一种毫米波调谐微带滤波器的研制

该文基于金丝键合工艺和薄膜工艺,实现了一种低插损、小型化毫米波调谐微带滤波器。首先提出了一种加载矩形孔的半波长开路可调谐振器,通过在不同矩形孔上键合金丝来改变谐振器的等效电感值,从而改变谐振频率。然后利用所提出的可调谐振器实现了一种Ka频段五阶调谐带通滤波器,通过改变键合金丝状态来调谐频率,实现仿真和实测结果之间的偏差修正,解决了在毫米波频段由于介电常数批次性差异以及加工误差等因素造成的窄带滤波器频率偏移的问题。为了验证其可行性,对五阶调谐微带滤波器进行仿真、优化、加工及测试。结果表明,该滤波器的通带可调范围为35.35~35.95 GHz,插入损耗小于4.6 dB,能够实现所需通带。     

一种新颖的基于AFMLF的双倍布里渊频移间隔的MWBEL

提出了一种基于非线性放大光纤环形镜(AFMLF)滤波器的双倍布里渊频移间隔的多波长掺铒光纤激光器(MWBEL)环形腔结构,其中非线性放大光纤环形镜被用作滤波器。当980nm泵浦功率为10.29dBm、可调激光源(TLS)的中心波长为1 563nm、功率为-3dBm时,得到了波长间隔为0.16nm的12阶偶数阶多波长激光输出。同时,还研究了980nm抽运功率、偏振控制器(PC)以及可调激光源的中心波长对输出斯托克斯光波数的影响。     

一种具有可重构陷波功能的差分宽带带通滤波器

文章提出了一种具有陷波可重构功能的差分宽带带通滤波器,具有良好的差模响应与共模抑制效果。所设计的差分带通滤波器通过采用对称的四阶分支线结构,在差模激励下可等效出电壁,在共模激励下可等效出磁壁。同时,该滤波器通过对称地耦合两个1/4波长的阶梯阻抗谐振器来产生所需频段的陷波特性,并通过改变阶梯阻抗谐振器上变容二极管两端的直流偏置电压来改变阶梯阻抗谐振器的电长度,从而调整陷波的频段。仿真和测试结果表明该差分带通滤波器的工作频带为2.7~7.3 GHz,相对阻抗带宽为92%。在工作频段中,差模回波损耗均大于10 dB,共模抑制大于15 dB。随着变容二极管两端直流控制电压从10.3 V变化到3.6 V,陷波的中心频率从5.6 GHz移动到6.1 GHz,同时滤波器宽带带通特性基本保持不变。     

Narrow-band light source with acoustooptic tunable filter for optical low-coherence reflectometry

An electrically-tunable narrow-band light source with no moving parts is constructed for jaggedness-free optical low coherence reflectometry. The source incorporates a double-path acoustooptic tunable bandpass filter module whose two passbands automatically agree to within 0.2 nm during wavelength tuning from 1529-1568 nm. The source emits narrow-band light with an FWHM of 1.8/spl plusmn/0.1 nm, a power of >0 dBm and a suppressed background spectrum. The entire wavelength range can be swept electrically within 100 ms by using a variable RF source.     

Mode-Hop-Free, Optical Frequency Tunable 40-GHz Mode-Locked Fiber Laser

We have successfully achieved a mode-hop-free, optical frequency tunable 3-ps 40-GHz mode-locked fiber laser by installing an optical etalon in a 6.8-m laser cavity. The laser frequency was continuously tuned over 1 GHz without mode hopping by tuning the etalon peak frequency. The oscillation wavelength was also tuned over 1535-1560 nm by tuning an optical bandpass filter installed in the laser cavity.