基于氟碲酸盐光纤的高功率中红外超连续光源(特邀)

高功率全光纤中红外超连续光源在基础科学研究、环境、医疗以及国防安全等领域有着重要应用。目前用于研制上述光源所用的非线性介质为氟化物玻璃光纤。但是氟化物玻璃光纤的损伤阈值低、化学稳性差,这在一定程度上影响了氟化物玻璃光纤在实用化高功率中红外光源研制中的应用。为了进一步提升中红外超连续光源的性能和研制实用化高功率中红外超连续光源,最近制备出了一种具有较好热稳定性和化学稳定性的氟碲酸盐玻璃（TeO2-BaF2-Y2O3,TBY）,并利用其作为基质材料,设计制备出了一系列氟碲酸盐玻璃光纤。利用这些光纤作为非线性介质,研制出了光谱范围覆盖1.4~4 m的高相干超连续光源,光谱范围覆盖0.4~5.14 m的宽带超连续光源和平均功率大于10 W、光谱范围覆盖947~3 934 nm的超连续光源。     

High-power mid-infrared supercontinuum sources: Current status and future perspectives

Mid-infrared (mid-IR) supercontinuum (SC) sources have recently gained much interest, as a key technology for such applications as spectral molecular fingerprinting, laser surgery, and infrared counter measures. However, one of the challenges facing this technology is how to obtain high power and broadband light covering a spectral band of at least 2–5 µm, especially with a very efficient output power distribution towards the mid-IR region. This directly affects their usage in the practical applications mentioned above. Typically, an SC is generated by pumping a piece of nonlinear fibre with high-intensity femtosecond pulses provided by mode-locked lasers. Although this approach can lead to wide continuum generation, the output power is limited only to the milliWatt level. Therefore, to achieve high-power SC light, other laser systems need to be employed as pump sources.This paper briefly reviews SC sources, restricted to those with an average output power of over 0.4 W and simultaneously with a long-wavelength edge of the continuum spectrum of over 2.4 µm. Firstly, the concepts of SC generation, including the nonlinear phenomena governing this process and the most relevant mid-IR fibre materials, are presented. Following this study, a review of the main results on SC generation in silica and soft-glass fibres, also including my experimental results, is presented. Emphasis is given to high-power SC generation with the use of different pump schemes, providing an efficient power distribution towards longer wavelengths. Some discussion and prospective predictions are proposed at the end of the paper.     

掺铒光纤ASE宽带光源的实验研究

掺铒光纤ASE源是一种优良的宽带光源,受到人们广泛关注.实验研究了掺铒光纤ASE宽带光源单、双程结构后向ASE输出光谱特性,当泵浦光中心波长为1480 nm时,分别考察了掺铒光纤长度、泵浦光功率对后向ASE输出平坦区间宽度和平坦度的影响.通过对两种结构下后向ASE输出光谱的分析比较发现,双程结构在L波段长波长处,尤其是1570～1620 nm波长范围,功率显著提升,从而使得ASE光谱的平坦区间宽度增大,平坦度提高.所得实验结果将为掺铒光纤ASE宽带光源的研制提供依据.     

6 ~ 18 GHz 脊波导宽带功率合成放大器

提出一种不通过波导脊背与微带导带接触来实现脊波导-微带射频信号过渡的新型电路,具有工作频带宽、插入损耗小、电性能稳定等优点,非常适合工程应用。通过对该非接触式脊波导-微带过渡与Lange 电桥进行理论分析与仿真计算,提出了一种可覆盖C/ X/ Ku 频段的宽带功率合成方法,并按照该方案在6 ~18 GHz 频段内设计了一种以脊波导为射频端口的高效率2 路功率合成放大器。实测结果表明,6 ~18 GHz 频率范围内的无源合成效率高于87%。采用该电路将典型输出功率12 W 的2 只MMIC 的输出功率合成,在6 ~18 GHz 频率范围内得到了高于20 W 的饱和功率输出,附加效率最高可达28. 9%。该宽带功率合成放大器以脊波导为接口,不但功率容量大,且便于采用脊波导功率合成器进行高效率二次合成,为6 ~18 GHz 更大输出功率的固态功放研制提供了解决方案。     

2kW连续波磁控管设计与仿真

本文介绍了一种用于工、农业加热的连续波磁控管的研制过程,该磁控管工作频率2450MHz,输出功率2kW。该磁控管采用轴向能量输出结构,作为辐射天线插入激励波导中进行能量输出,阴极采用直热式螺旋形碳化钍钨阴极,整管体积小、重量轻、结构紧凑,便于安装和使用。     

高性能低成本的C+L波段掺铒光纤光源

为了得到一种高性能的C+L波段的宽带掺铒光纤光源,用一个980nm和一个1480nm激光二极管作为抽运源,用两个3dB宽带耦合器作为光纤反射镜,同时利用功率控制电路让光源输出光稳定,对设计的光源进行了实验和理论验证,获得了功率为168.67mW(22.27dBm)、带宽达到80.701nm(1525.112nm～1605.813nm)的C+L波段宽带光源。结果表明,开始用两个980nm和一个1480nm二极管作为抽运源,之后改为一个980nm和一个1480nm二极管作为抽运源,并没有减少光源的输出功率,也没有改变稳定性。这一结果对减少光源的成本、提高光光转换效率,具有实际价值。     

Mid-Infrared Raman Fiber Lasers

As mid-infrared (MIR) lasers show numerous applications in the field of defense, medical, materials processing, and optical communications. Investigation on MIR Raman fiber lasers (RFLs) increasingly becomes a hot topic. Compared with the traditional silica fibers, fluoride and chalcogenide glass fibers possess higher nonlinear coefficients and excellent MIR transmittances. In this article, the latest developments of the MIR RFLs using fluoride and chalcogenide glass fibers as gain media are introduced, respectively. This review article mainly focuses on the developments of MIR RFLs in aspects of output wavelength, output power, and optical efficiency. Besides, the prospect of MIR RFLs is also discussed.     

一种Ka波段宽带功率合成放大器的设计

随着电子对抗等宽带微波系统的日益发展,毫米波宽带功率放大器需求也越加强烈。近年来随着空间功率合成技术研究的深入开展,基于波导内的空间合成技术在合成效率、相对带宽和实用化方面均展现了良好的特性,受到了广泛的关注。介绍了一种新颖的小型化空间功率合成器,基于波导内空间合成技术,采用非均匀对极鳍线的等分过渡方式,对BJ320波导进行分层结构设计并实现了一种Ka全频段功率放大器,在32 mm×30 mm×24 mm总体积内实现了4路合成,显示出了良好的工作性能。     

High efficiency 1.3 mu m superluminescent diode with absorbing tapered waveguide

A new type of superluminescent diode (SLD) with a tapered waveguide in the absorbing region is proposed. This SLD structure monitors output power, as it emits monitor light from the rear facet that is about one-tenth the output power from the front one. Device parameters have been determined by beam propagation methods. A 1.3 mu m SLD fabricated by liquid phase epitaxy (LPE) with an absorbing waveguide 200 mu m long and with a 6.5 degrees tapered angle can emit output power of 13.5 mW from the front facet at a 200 mA driving current without lasing.<>     

高功率850 nm宽光谱大光腔超辐射发光二极管

超辐射发光二极管(SLD)具有不同于半导体激光器和普通发光二极管的优异性能。为提高半导体超辐射发光管的光谱宽度,采用非均匀阱宽多量子阱(MQW)材料拓宽超辐射器件的输出光谱。优化设计器件的波导结构,利用大光腔结构设计出高功率、低发散角850 nm超辐射发光二极管。采用直波导吸收区而后在器件的出光腔面上镀制抗反射膜的方法制作超辐射发光二极管。器件在140 mA时器件半峰全宽(FWHM)可以达到26 nm,室温下连续输出功率达到7 mW。器件的垂直发散角为28°,水平发散角为10°。由于器件具有比较小的发散角,与光纤耦合时具有比较高的耦合效率,单模保偏光纤耦合输出功率达到1.5 mW。     

超宽带高饱和单行载流子光探测器研究 （特邀）

超宽带单行载流子（UTC）光电探测器因其仅需快速的电子输运过程,较传统PIN探测器具有明显宽带优势,是6G宽带无线通信、太赫兹成像、超宽带噪声发生器等亚太赫兹频段系统中的核心光电子器件之一。面向亚太赫兹频段光电转换需求,针对UTC探测器中大带宽与高饱和功率之间的矛盾问题,分别研究并突破了光生载流子高速输运机理、感性共面波导器件（CPW）结构等关键技术,研制成功带宽106 GHz、饱和输出功率7.3 dBm的双漂移层结构MUTC探测器芯片,和带宽超过150 GHz的超宽带MUTC探测器芯片。     

1.3μm波段单横模大功率输出量子点激光器

为了制备大功率、单横模输出的量子点激光器,对有源多模干涉波导结构进行了研究。通过优化器件结构设计,采用1×1型有源多模干涉波导结构,以均匀多层InAs/InGaAs/GaAs量子点材料作为有源区,制备了1.3μm波段的有源多模干涉结构量子点激光器。连续电流注入条件下的测试结果表明,与传统的均匀波导结构器件相比,有源多模干涉结构器件具有更低的串联电阻和更好的散热性能;在连续电流为0.5A的小注入情况下,器件的输出功率可达114mW、中心波长为1332nm。结果表明,有源多模干涉结构器件是制备大功率、单横模输出光发射器件的一种有效的器件结构。     

Propagation Characteristics of a Partially Filled Cylindrical Waveguide for Light Beam Modulation

Propagation characteristics of a cylindrical waveguide partially filled with a cylindrical dielectric light modulation material is analyzed and numerical computation is performed for a few typical cases. This type of traveling-wave structure supports a TE or TM mode, and therefore is useful for light beam modulation applications requiring a longitudinal magnetic or electric field. Numerical analysis indicates that for the TM case, a broadband region occurs near a crossover point and broadband synchronization between the modulating microwave and the parallel-launched light beam can be obtained by a suitable choice of the dielectric medium surrounding the central dielectric.     

毫米波宽带波导功率合成器设计

毫米波宽带功率放大器是毫米波电子对抗系统的关键部件之一,宽带低损耗的波导合成器是实现毫米波宽带大功率合成放大器的关键。根据设计目标,分析比较了四端口波导合路器和无耗三端口波导合路器的优缺点,提出了毫米波宽带波导合成器的设计方案,用电磁场仿真软件HFSS对宽带波导功率合成器进行了建模和设计仿真,并制作了工作频率范围在26~40 GHz的功率合成器,对测试指标和仿真曲线进行了对比分析。实际测试结果表明,设计的波导合路器具有良好的工程实用价值。     

Evaluation of Thermal Crosstalk in Quantum Cascade Laser Arrays

The continuous-wave operation, thermal crosstalk measurements, and thermal modeling of a quantum cascade (QC) laser array are presented. Measurements and thermal modeling predict that the thermal crosstalk between array elements can be minimized by improving the heat management when the spacing of neighboring laser elements is greater than 500 mum. The output power of the demonstrated QC laser array significantly exceeds the output power of the individual lasers in the array. This shows the potential of the QC arrays as a candidate for the realization of high-power optical sources in mid-infrared (3-20 mum) spectral range     

Lead chalcogenide mid-infrared diode lasers fabricated byion-implantation

Ar⁺ implanted PbSe mid-infrared (MIR) lasers have been fabricated, characterized, and analyzed. For the first time, the operation of ion-implanted lead-salt mid-infrared diode lasers in continuous-wave (CW) mode at temperatures above 77 K was achieved. The maximum operating temperatures of 115 K in CW mode and 155 K in pulse mode were reached. These lasers have high output power, low linewidth, and small tuning rate, as well as comparatively low threshold currents. These promising properties demonstrated that ion-implanted MIR lasers are competitive candidates as tunable sources in the applications of high-resolution spectroscopy and trace-gas analysis     

一种功率可调的稳定激光光源的实现方法

在光纤通信系统测试中,波长为850 nm、 1310 nm、1490 nm、1550 nm和1625 nm 等的红外激光光源作为信号源具有广泛的应用。该光源需要 具有稳定的输出光功率。通常采用含有衰减片的光 衰减器对其输出光功率进行调节以满足不同场合的测 试与校准需求。通过分析激光器输出功率与 驱动电流的特征曲线,提出了一种在电路上采用压控电 流的方法,实现了稳定光源的输出光功率步进可调(调 节范围为30 dB)。该方法可有效减少光衰减器的使用,缩减测 试系统的仪器数量,提高测试效率,降低测试成本。     

硅基光子集成宽带大色散延时芯片（特邀）

集成、宽带、大色散延时的器件在微波光子滤波、真延时相控阵天线等领域有着重要的应用,可以有效地降低系统尺寸和功耗。文中提出并实现了一种基于硅基光子集成的宽带大色散延时芯片,通过采用超低损耗波导结构和侧壁法向量调制结构实现了片上集成大色散波导光栅,色散值超过250 ps/nm, 最大群延时达到2440 ps,带宽大于9.4 nm,该芯片有望用于微波光子学、高速光纤通信系统等领域。     

2.4 μm波段全正色散飞秒克尔透镜锁模激光器（特邀）

2 μm波段的飞秒激光光源在高分辨分子光谱学、中红外光学频率梳产生和超宽光谱的中红外光源产生等方面都具有重要的应用价值。Cr: ZnS/ZnSe具有很宽的发射峰,使其成为该波段产生宽光谱短脉冲中红外飞秒激光的重要材料。全正色散锁模的飞秒激光由于更容易实现较短的脉冲宽度与较高的峰值功率而受到青睐。文中在Cr: ZnS上实现全正色散条件下的克尔透镜锁模运转。在5.1 W的泵浦功率下实现波长覆盖范围2.0~2.7 μm,平均功率660 mW,脉冲宽度37 fs的稳定锁模脉冲输出,这是首次在Cr: ZnS中实现全正色散锁模运转的固体激光器。Cr:ZnS 全正色散锁模的飞秒激光器在高分辨分子光谱学、宽光谱中红外光光源产生等方面具有广阔的应用前景。     

A Technique for Measuring Individual Modes Propagating in Overmoded Waveguide

A practical measurement technique for determining the relative amplitude and phase of the individual modes propagating in overmoded waveguide is described. A phase-sensitive detector is used to measure the output of fixed probes placed around a single transverse plane in a section of enlarged waveguide. The detected output is directly proportional to the modal components, and data reduction is performed manually. The use of oversize waveguide provides increased accuracy and permits total multimode power measurements in conjunction with mode analysis. The technique can be used for mode measurements up to the fourth harmonic in standard rectangular waveguide. Experiments described in the paper use a single frequency source. However, signal sources with spurious content can be evaluated using appropriate tunable RF band-pass filters.