带宽可调的斜边光纤光栅滤波器的设计与制作

基于遗传算法设计了斜边三角形光纤光栅(EFBG)的折射率调制函数;提出了光纤外径沿轴向变化、在拉应力下可获得可调谐的斜边三角形光纤光栅;计算分析了该器件多个物理参量对反射光谱的影响。在实验中,采用紫外激光扫描辐照方法,制备了短波边斜边带宽为0．7nm、反射率为96％的斜边三角形光纤光栅;采用程序控制氢氟酸腐蚀方法获得外径从原始62．5μm减小到45μm、在85mm长度内按设计要求变化的光纤光栅。对该光纤光栅施加从。到1．715N变化的拉力时,其反射光谱短波边的斜边带宽从0．7nm增加到2．3nm,实现了一种带宽大范围可调的斜边光纤光栅。     

Stable and continuous wavelength tuning of a hybrid semiconductor laser with an erbium-doped fiber external cavity

We present an experimental study of tuning characteristics and wavelength stability of a 1490 nm doped fiber external cavity laser. The standing wave in the erbium-doped fiber in an external-cavity laser causes spatial hole burning and absorption modulation and forms a dynamic grating. The dynamic grating can effectively suppress side modes and eliminate wavelength fluctuations in the laser. The operating wavelength of this hybrid laser is shown for the first time to our knowledge to be smoothly tunable by changing the semiconductor laser drive current or temperature.     

基于光纤光栅的可调谐半导体激光器

本文利用光纤光栅(FBG)形成外腔反馈及F-P半导体激光器的多模特性,得到波长稳定、可调谐的半导体激光光源,系统研究了不同反馈比率对激光器光谱特性的影响.通过向FBG施加轴向拉力和压力可实现10nm的波长调谐,得到一系列波长间隔0.94nm的激光输出,边模抑制比达35dB,光谱线宽小于0.2nm.     

73-nm tuning of a double-clad Yb<Superscript>3+</Superscript>-doped fiber laser based on a hybrid array

We report on a wide wavelength tuning in a double-clad ytterbium-doped fiber laser. The laser cavity consists of an array of broadband high-reflection fiber Bragg gratings and a bulk grating as the output coupler and wavelength selection element. The proposed fiber laser configuration combines a low intracavity loss of the fiber Bragg grating mirrors with a wide wavelength tuning of the bulk gratings. We demonstrate a >70-nm wavelength tuning range, limited only by the available fiber Bragg gratings.     

Tunable Bragg gratings for fiber lasers

A tuning method of a fiber Bragg grating by the bending compression-tension is considered. With this method, a relative tuning range of the resonance wavelength of the grating of about 5% has been obtained. The changes in the shape of the spectrum and in the grating reflectivity during the tuning process are studied. The reflectivity of the fiber Bragg grating has been found to considerably increase with increasing degree of compression. It is shown that such an increase is caused by compression-induced changes in the refractive index modulation amplitude in the grating. The fiber Bragg grating developed has been applied for tuning the radiation wavelength of an ytterbium fiber laser. The tuning range of the laser has been found to be 45 nm around the central wavelength 1080 nm.     

波长无啁啾调谐窄线宽掺Yb3+双包层光纤激光器

用相位掩模法, 在圆形掺Yb3+双包层光纤上制作了Bragg光纤光栅,并用它作为双包层光纤激光器的输出腔镜, 在光栅反射中心波长1055.2 nm位置得到了窄线宽的激光输出, FWHM为0.271 nm, 信噪比约为40 dB.这种结构的双包层光纤激光器, 在双包层增益光纤和后腔镜间没有连接损耗, 减小了双包层光纤激光器体积. 用自行制作的等强度梁对作为输出腔镜的光纤光栅做双向应力调谐, 实现了激光波长无啁啾调谐输出, 调谐范围1051.1~1060.04nm,调谐量达8.9nm, 调谐过程中激光3 dB线宽基本无变化.     

Compact diode-pumped passively Q-switched tunable Er-Yb double-clad fiber laser

Efficient repetitive passive Q switching of a cladding-pumped Er-Yb fiber laser has been demonstrated by use of an external-cavity configuration containing a Co(2+): ZnS crystal as a saturable absorber. Energies of as much as 60muJ in pulses of durations as short as 3.5 ns (FWHM), corresponding to a peak power of >10kW, have been generated, and the maximum slope efficiency with respect to the absorbed pump power was 13%. Using a bulk diffraction grating in the Littrow configuration to provide wavelength-selective feedback, we tuned the passively Q -switched fiber laser over 31 nm from 1532 to 1563 nm. The prospects for further improvement in performance are discussed.     

Fabrication of High Reflection UVWritten Fiber Bragg Gratings

l.IntroductionFibergratingshaveattractedanincreasingamountofattentionsineeG.Meltz[1Jandhisco-workersfirstdemonstratedinl989thatPermanentgratingscouldbewrittenbyex-peinganoPticalfiberfromthesidetotwointerferingbeamsofultraviolet(UV)light.Inrecentyears,avastresearchefforthasbeendevotedtoopticalfiberBragggratingsallovertheworld.Theirsimplicity,usefu1nesscoupledtotheiruniqueproPertiesandnu-merousadvantagesmakethemidealforawiderangeofimPOrtantapplicationsinopticalfibertelecommunications,lasersa…     

Refractive-index gratings written by near-ultraviolet radiation

This is the first report, to our knowledge, of refractive-index grating side writing in 10 mol.% GeO(2)-doped fiber by the near-UV light of a cw Ar(+) laser (333-364 nm). An induced-index magnitude as large as 1.9 x 10(-4) at 1.7x10(5) W/cm(2) UV power density has been achieved. The observed gratings have exhibited the same temperature stability as gratings written by a KrF excimer laser (248 nm).     

Tunable Ytterbium-Doped Fiber Laser Based on a Mechanically Induced Long Period Holey Fiber Grating

We describe a tunable double-clad Yb-doped fiber laser based on a long period fiber grating mechanically induced in a section of single mode holey fiber inserted into the laser cavity. The mechanically induced long period holey fiber grating acts as a wavelength-selective fiber filter whose central wavelength, linewidth, and strength can be tuned by changing the period, the length of the grating, and the applied pressure. The fiber laser gives a ∼12.6 nm tuning range, from ∼1079:4–1092nm, with slope efficiencies of 18.7–26.3% at this wavelength range, with respect to the launched pump power.     

High-energy femtosecond fiber laser at 976 nm

We report on a passively mode-locked fiber laser emitting around 976nm. The self-starting mode locking is achieved in an unidirectional ring cavity by means of nonlinear polarization evolution. Stable single-pulse operation is observed for 480mW of average output power. This all-normal dispersion laser generates naturally chirped pulses with 1ps duration. The repetition rate is 40.6MHz, resulting in 12nJ pulse energy. External compression using bulk grating shortens the pulse duration down to 286fs.     

Stable dual-wavelength erbium-doped fiber ring laser with switchable spacing employing controllable channel loss

A stable dual-wavelength erbium-doped fiber ring laser with switchable spacing is proposed and experimentally demonstrated. An arrayed waveguide grating (AWG) incorporating two fiber optic switches (OS) is used to as the wavelength selector. The ring cavity is divided into two cavities by a 30:70 optical coupler. Equalized dual-wavelength outputs are achieved by controlling the variable optical attenuator (VOA) inserted in the lower loss cavity. The wavelength spacing can be tuned from 0.80 to 12.05 nm. The fiber laser has good optical quality with maximum power fluctuation of 1.5 dB and side mode suppression ratios (SMSRs) higher than 71 dB.     

基于飞秒激光直写光纤光栅的掺镱光纤激光器

 利用飞秒激光微加工技术,可以在光纤纤芯内直写出布拉格光栅,它与传统的光纤光栅制作方法相比,具有耗时短、无需光敏光纤、周期可任意设定、光栅稳定性高等优点。采用800 nm钛宝石飞秒激光器,在Hi1060光纤内写入一支8 mm长的布拉格光栅,光纤光栅的周期为2.9 μm,这是中心波长为1 042 nm的八阶光纤布拉格光栅。将所得光栅与一段有源的双包层光纤熔接,作为激光输出镜,利用975 nm的LD光纤模块作为泵浦源,采用端泵浦技术构成双包层光纤激光器。双包层光纤采用Nufern公司镱(Yb³⁺)离子掺杂双包层光纤,光纤长度3 m。所得激光器的输出功率为71.1 W,中心波长1 042 nm,带宽约为0.8 nm。     

电流调谐光纤光栅外腔分布布拉格反射激光器

报道一种新颖的波长可调谐光纤光栅外腔分布拉格反射激光器。把经过金属管封装的光纤面布拉格光栅作为激光二极管的外腔反射镜,得到的单模激光输出不仅线宽窄,边模抑制比高,而且,调节流过金属管的电流,可在5nm范围内的6个不同波长间转换。     

载氢光纤光致折变布拉格光栅

报道用１９３ｎｍＡｒＦ准分子激光，经过石英相位版的空间调制，在载氢增敏处理过的通信光纤上写入光致折射率变化的布拉格光栅，在光栅布拉格波长上（λ＝１．５３μｍ）测得的反射率大于９０％，半高全宽线宽小于０．６ｎｍ。     

全光纤色散腔掺铒光纤激光器

报道用９７１ｎｍ半导体激光器泵浦的掺铒光纤激光器的一些实验研究结果。演示了由光纤环反射器和光纤光栅构成的全光纤色散掺铒光纤激光器，在１．５５μｍ波段获得了线宽小于０．０５ｎｍ的激光输出。     

High-repetition-rate picosecond pulse generation at 1.5 microm by intracavity laser frequency modulation

We propose and experimentally demonstrate generation of transform-limited pulse trains at a 2.5-GHz repetition rate from a frequency-modulated erbium-ytterbium bulk glass laser by using an intracavity lithium niobate phase modulator and an external fiber Bragg grating filter. Light pulses with durations tunable from 40 to 80 ps and 0.2-mW fiber-coupled average power at 1535 nm have been obtained.     

紧凑型窄线宽分布反馈光纤激光器

 在铒/镱共掺杂有源光纤上直接刻蚀光栅,制成一台紧凑型非对称π相移分布反馈光纤激光器。光栅总长度约50 mm,最佳相移位置在29 mm处,最佳耦合系数为150 m^-1。采用980 nm激光二极管同向泵浦,当最大泵浦功率为200 mW时,在1 550.94 nm处实现约10 mW激光输出,线宽小于0.05 nm,阈值约35 mW,斜率效率为6.06%,总光 光转换效率为5%,基本满足长距离光通信系统光源功率实用化的要求。     

A High Efficiency Yb3+-doped Fiber Ring Cavity Laser with Narrow Line-width

A novel Yb3+-doped fiber ring cavity laser pumped by a 977 nm laser diode is presented with its output laser wavelength of 1060 nm. Based on a fiber Bragg grating (FBG), the laser exhibits 0.20 nm line-width, 7.5 mW laser output power, 40 dB signal-to-noise ratio (SNR) and 66% slope efficiency.     

Single-step writing of Bragg grating waveguides in fused silica with an externally modulated femtosecond fiber laser

For the first time to our knowledge, high-strength (>30 dB) first-order Bragg grating waveguides were fabricated in bulk fused silica glass in a single-scanning step by modulating a high-repetition-rate femtosecond fiber laser with an external acousto-optic modulator. The modulation induced a waveguide segmentation by delivering controlled bursts of laser pulses to define an array of partially overlapped refractive index voxels. With appropriate choice of modulation frequency and sample scanning speed, low loss waveguides could be formed at high writing speeds to yield sharp Bragg spectral resonances tunable over the 1300 to 1550 nm telecom band. Effects of acousto-optic modulation duty cycle on propagation loss and grating strength are characterized. This modulation method offers facile control and integration of multiwavelength Bragg grating devices to enhance overall functionality of optical circuits in three-dimensional geometries.