光纤饱和吸收体稳频窄线宽光纤激光器

结合光纤饱和吸收体与光纤光栅法布里-珀罗标准具,研制出了全光纤结构1550nm单频窄线宽掺铒光纤环形激光器.采用两个976nm激光二极管双向抽运作为抽运源,高掺杂浓度铒光纤作为增益介质,以行波腔消除空间烧孔效应,利用光纤光栅法布里-珀罗标准具窄带选模特性,以10m长低掺铒光纤饱和吸收体稳频,得到了十分稳定的窄线宽激光输出.激光器抽运阈值功率21mW,在抽运光功率为145mW时输出光功率39mW,斜率效率30%,信噪比大于50dB.采用延迟自外差方法精确测量光纤激光器线宽小于10kHz.     

铒镱共掺磷硅酸盐光纤的制备及其激光性能研究

利用改进化学气相沉积法(MCVD)的反向沉积工艺,结合无铝的溶液掺杂技术,制备了高性能掺磷石英基的铒镱共掺光纤.反向沉积技术表现出了在纤芯中大量沉积磷这类高温下极易蒸发成分上的优势.研究表明,这种光纤中,铒镱离子能量传递效率极高,掺磷的石英基质对于促进镱离子对铒离子的能量传递,抑制镱离子寄生荧光作用明显.最后,搭建了双包层铒镱共掺光纤激光器系统,在光纤长度为4 m时,获得了3.2 W的最大功率输出,斜率效率达30%.     

非对称光纤反射镜的可调谐光纤激光器

提出一种非对称窄带光纤环形反射镜结构的可调谐掺铒光纤激光器。980nm泵浦光对掺铒有源光纤进行抽运,高双折射光纤、偏振控制器（PC）和光纤耦合器构成窄带光纤反射镜,窄带光纤反射镜和普通光纤反射镜组成激光谐振腔,利用窄带光纤反射镜工作带宽纳米量级的特性得到单纵模激光。调整偏振控制器改变反射镜对不同波长的反射率,实现可变波长的激光输出。实验表明,该激光器的工作带宽为8nm,120mW泵浦光条件下最大输出功率为4mW,3dB带宽（脉冲的半高宽度）小于0．2nm,边模抑制比为20dB以上,在1527nm～1535nm的波长范围内观察到稳定激光输出。     

光纤光栅环形镜的全光纤调Q 掺铒光纤激光器

报道一种新型全光纤调Q掺铒光纤激光器,在其结构中采用带有光纤光栅的光纤环形镜作 为调Q装置。此调Q方案同时提供了腔内损耗调制和对激光输出波长选择的功能。与声光、电光等调Q相比,其输出脉冲比较宽。但此全光纤Q开关装置与光纤熔接损耗小,从而克服了体光学调制器与光纤对接时插入损耗高的特点。     

宽带铋基掺铒光纤放大器增益及噪声特性研究

利用Er3 离子四能级结构速率方程组和光功率传输方程组,数值模拟了铋基掺铒光纤放大器(EDFA)的增益及噪声特性,模拟结果与实验报道结果取得了很好的一致。同时,详尽地分析了增益及噪声特性与光纤长度、泵浦功率和输入信号功率的关系,优化了放大器的性能,从理论上得出一个20dB增益带宽达76nm、噪声系数接近4dB的铋基EDFA。研究表明了铋基掺铒光纤放大器适合用作于现代DWDM系统中C L波段的光纤放大器。     

TiCN作为可饱和吸收体的2.8μm被动调Q锁模光纤激光器

本文报道了一种基于材料可饱和吸收的2.8μm被动调Q锁模掺铒氟化物光纤激光器。通过将TiCN颗粒作为可饱和吸收体直接涂覆于反射腔镜,并结合氟化物光纤垂直端面的输出耦合,实现了具有较低激光阈值和紧凑腔结构的2.8μm脉冲光纤激光器。该激光器在泵浦功率达到330 mW时,开始出现调Q锁模脉冲。随着泵浦功率持续增大,调Q脉冲包络重复频率从14.34 kHz增加至32.57 kHz,对应的脉冲宽度从10.51μs减小至5.40μs。在650 mW的泵浦功率下,获得最大平均输出功率25.83 mW,斜率效率为7.2%。     

L波段掺铒光纤超荧光光源和放大器研究

通过优化铒光纤长度,获得了平坦谱宽达30nm(0.7dB)的L波段超荧光光源,该光源具有7.21dBm的输出功率。在此基础上,研究L波段放大器增益特性,通过对铒光纤长度的进一步优化,用1480nm激光器作前向泵浦源,实验上获得了波长从1565nm~1595nm范围平坦的增益带宽,小信号增益可达22dB。     

基于Sagnac环形滤波器的多波长掺铥光纤激光器

为了实现2μm波段多波长激光输出,提出并设计了一种基于Sagnac环形滤波结构的多波长掺铥光纤激光器.激光器由波长793 nm的泵浦源、波分复用器、光纤耦合器、保偏光纤、掺铥光纤以及偏振控制器构成,其中Sagnac环形滤波器以及光纤环形镜作为激光器的反射端.实验中,激光器工作阈值为77.5 m W,通过调节偏振控制器,实现了稳定的单波长激光输出.波长为1 852.8 nm的单波长激光输出时,在50 min监测时间内波长最大漂移为0.1 nm,功率最大漂移为0.252 d B,激光3 d B线宽和信噪比分别为0.3 nm和35.7 d B.通过调节偏振控制器,在1 850~1 900 nm光谱范围内实现了1~4波长的激光输出.     

掺铒碲基单模光纤的制备及其放大自发辐射光谱

制备了一种新型的可应用于1．5μm通讯窗口宽带放大自发辐射光源的掺铒碲酸盐玻璃单模光纤（EDTF），并分析了其热学性质和光谱特性、该玻璃显示了良好的热稳定性（△T〉150℃）和匹配的热膨胀系数．采用自制EDTF短光纤，组装了超荧光单程反向结构光源（SPB），利用波长为980nm的半导体激光器抽运掺Er^3＋的碲酸盐短光纤，可在1450-1650nm范围获得宽带宽的铒离子放大自发辐射光谱（ASE）．研究了光纤长度，泵浦功率等对放大自发辐射光谱的影响．研究结果显示，该碲酸盐玻璃是一种适用于宽带放大自发辐射光源的基质材料．     

基于可饱和吸收稳频技术的光纤激光应变传感特性研究

提出了一种环形光纤激光用于光纤传感的方法,结合光纤可饱和吸收体稳频技术,获得稳定的激光输出,并成功将其应用于应变传感.使用980 nm激光二极管作为泵浦源,长度为2 m的掺铒光纤作为增益介质,通过光环形器引入未泵浦的掺铒光纤作为可饱和吸收体形成窄带滤波器,并选用高反射率光纤光栅作为波长选择元件.可饱和吸收体长度为4 m时获得了稳定的激光输出,输出3 d B带宽小于0.2 nm,边模抑制比大于70 d B,阈值电流为63.3 m A.通过选频光纤光栅对等强度梁应变的感知引起的光纤激光输出调谐,实现0~2 100με应变传感检测,对这种掺铒光纤激光的应变特性进行了实验研究,得到了应变与激光峰值波长的线性关系.实验结果表明:该激光传感器获得了很好的线性度和重复度,线性拟合度高于0.999.     

Tunable single longitudinal mode S-band fiber laser using a 3 m length of erbium-doped fiber

In this paper a tunable single-longitudinal mode (SLM), short-wavelength band (S-band) fiber laser using a conventional erbium-doped fiber (EDF) with a length of 3?m and a step index erbium dopant profile as opposed to the commonly used depressed cladding erbium-doped fiber (DC-EDF) is proposed and demonstrated. The proposed SLM fiber laser has a tuning range of 1496 to 1507?nm in a ring configuration using two 0.15?m of EDF which acts as saturable absorbers (SAs). The highest peak power measured is about ?0.6?dBm at a wavelength range of 1502 to 1507?nm. The measured signal-to-noise ratio (SNR) is approximately 74?dB for the same wavelength range. The line-width of the SLM output is measured to be 140?kHz.     

SOA-based multi-wavelength source

A simple fiber laser configuration based on a semiconductor optical amplifier (SOA) is proposed for obtaining multi-wavelength oscillation at room temperature, in which a Sagnac loop mirror is used as the wavelength selective component. The SOA has a flat gain of approximately 23dB within a bandwidth of 12 nm at a small input signal power. The loop mirror was constructed using a 3dB coupler and polarization maintaining fiber (PMF). The output spectrum of the proposed laser can be adjusted by controlling the bias current of the SOA and is quite stable at room temperature. At a bias current of 150 mA, six lines are obtained with at least ?40 dBm output power and 25dB signal-to-noise ratio (SNR). The channel spacing and number of lines is determined by the length of polarization maintaining fiber (PMF) used in the loop mirror. The channel spacing of the proposed laser is 1.49 nm with a PMF 3 m. The multi-wavelength comb output can also be tuned by adjusting the operating temperature of the SOA. The multi-wavelength laser has the advantage of a simple configuration, stability at room temperature, a broad wavelength band, and no need for optical pump lasers.     

Bismuth-based Brillouin/erbium fiber laser

A multi-wavelength Brillouin/erbium-doped fiber laser (BEFL) operating in the 1573 nm region is proposed and demonstrated. The system employs both linear and nonlinear gain from a bismuth-based erbium-doped fiber (Bi-EDF) approximately 215 cm long and a single mode fiber (SMF) of various lengths to generate an optical comb with a spacing of approximately 0.089 nm. Two 3 dB couplers were used to form a looping arm in the system in order to produce cascaded Brillouin Stokes waves as internal feedback for multi-wavelength operation. A stable output laser comb with 10 lines at more than ??13 dBm was obtained with 4.85 dBm Brillouin pump power and two 140 mW pumps at 1480 nm. The 1480 nm pumps' power and SMF length have a significant effect on the number of wavelengths and on the output power of the generated wavelength comb.     

Generation of stable and narrow spacing dual-wavelength ytterbium-doped fiber laser using a photonic crystal fiber

Abstract

We demonstrate the design and operation of novel narrow spacing and stable dual-wavelength fiber laser (DWFL). A 70-cm ytterbium-doped fiber has been chosen as the gain medium in a ring cavity arrangement. Our design includes a short length photonic crystal fiber, acting as a dual-wavelength stabilizer based on its birefringence coefficient and nonlinear behavior and tunable band pass filter (TBPF) to achieve narrow spacing spectrum lasing. Our laser output is considered to be highly stable, with power fluctuation less than 0.8 dB over a period of 15 min. The flexibility and tunability of TBPF, together with polarization controller enable the spacing tuning of the DWFL from 0.03 nm up to 0.07 nm for 1040 nm region, and 0.10 nm up to 0.40 nm for 1060 nm region. The tunable wavelength spacing shows the flexibility of the DWFL in addition to stable and reliable properties of fiber laser in 1-μm region.     

Switchable triple-wavelength thulium-doped fibre laser based on a Mach–Zehnder interferometer and fibre ring filter

A switchable triple-wavelength thulium-doped fibre laser based on an all-fibre Mach–Zehnder interferometer and fibre ring filter with a polarization-maintaining fibre is proposed and experimentally demonstrated. In the proposed fibre laser, a Mach–Zehnder interferometer comprising two 1 × 2 optical couplers is inserted into the optical cavity to produce the comb filter effect. The fibre ring filter comprises two optical couplers with a 3:7 splitting ratio and a 2-m-long polarization-maintaining fibre to improve lasing stability. Single-wavelength lasing can be tuned continuously from 1864.4 to 1884.5 nm, and five different modes of dual-wavelength and switchable triple-wavelength lasers can be realized by changing the polarization state. The signal-to-noise ratios of all lasers are more than 33 dB. The maximum power fluctuations and wavelength variations are less than 1.5 dB and 0.3 nm at room temperature, respectively, and the 3 dB bandwidth is less than 0.2 nm. The results demonstrate that stable and switchable single- or dual-wavelength lasers can be generated using the designed fibre laser.     

Technique for continuous tuning of optical fiber lasers

For the first time to the authors' knowledge, we have demonstrated how thermally controlled overcoupled fused fiber couplers and fiber loop mirrors based on these couplers can be used as broadband tuning elements in a fiber laser cavity. No bulk optical elements play any role in this technique. Temperature tuning the coupler results in a shift in the coupling ratio or in the effective output coupler transmission. For a fixed pump source, and for a given laser cavity, this shift causes the lasing wavelength to shift. We have continuously tuned an Er silica fiber laser in this manner over the range of 1527-1570 nm in a ring configuration, and, using a fiber loop mirror with these couplers in a linear Tm silica fiber laser cavity, we have achieved more than 50-nm broadband tuning over the range of 1850-1910 nm. The tuning range and the sensitivity to temperature depend on the degree of overcoupling of the loop mirror coupler.     

Bismuth activated alumosilicate optical fibers fabricated by surface-plasma chemical vapor deposition technology

Plasma chemical technology is experimentally applied to the fabrication of a Bi-activated alumosilicate-core pure-silica-cladding fiber preform. To the best of our knowledge, this is the first time this technology has been applied in this way. We measure gain efficiency at pumping by a 1058 nm wavelength Yb fiber laser in a piece of a newly obtained fiber 20 m in length within 100-1200 nm wavelengths band. The gain efficiency reaches as high as 0.2 dB/mW. Bi-activated alumosilicate-core pure-silica-cladding fiber that is not more than 12 m in length serves a basis for a 1 W output power fiber laser emitting at the wavelength of 1160 nm with 8% slope efficiency. We also measure the photoluminescence spectrum and kinetics of Bi centers responsible for laser emission under the excitation of 193 nm wavelength ArF laser pulses.     

High-power widely tunable thulium fiber lasers

Applications requiring long-range atmospheric propagation are driving the development of high-power thulium fiber lasers. We report on the performance of two different laser configurations for high-power tunable thulium fiber lasers: one is a single oscillator utilizing a volume Bragg grating for wavelength stabilization; the other is a master oscillator power amplifier system with the oscillator stabilized and made tunable by a diffraction grating. Each configuration provides >150 W of average power, >50% slope efficiency, narrow output linewidth, and >100 nm tunability in the wavelength range around 2 μm.