长外腔半导体激光器的调谐连续性

可调谐外腔半导体激光器（ＥＣＬＤ）中的波长选择元件（如光栅，Ｆ－Ｐ标准具等）所选择的波长函数具有一定的频谱宽度，为实现连续调谐该宽度就应足够小，作为首次尝试，在研究了确保ＥＣＬＤ能在激光二极管的以共振长振荡所需的条件后，我们导出该谱宽不能超过的上限值。     

Multifunctional photonic switching operation of 1500 nm Y-coupledcavity laser (YCCL) with 28 nm tuning capability

The authors present new results on extended electrical tuning, fast spatial switching, and optically controlled wavelength conversion characteristics for the recently developed InP-based Y-laser structure. The devices have a 80 nm thick bulk InGaAsP active layer and are completely grown by metalorganic vapor phase epitaxy. The facets at both ends of the chip are as-cleaved without antireflective coating. The addressable range for electrically controlled wavelength switching was extended to the record value of 28 nm. When operated as a lossless 1:2 optical space switch, fiber-to-fiber gain >0 dB, extinction ratio >50 dB and high speed operation up to 1 Gb/s were shown. Optically triggered tunable wavelength conversion including dynamic operation was also demonstrated     

1 339 nm单一谱线Nd:YAP脉冲激光器

介绍了一台a轴偏振的1 339 nm Nd:YAP脉冲激光器.通过分析Nd:YAP晶体的能级跃迁和光谱特性,采用偏振片抑制平行于晶体C轴偏振的激光振荡,并通过设计输出耦合镜的透过率抑制晶体a轴偏振的1 064 nm强线的振荡,成功实现a偏振的1 339 nm单一谱线脉冲激光输出.当输入电能量达到75 J时,激光输出能量为0.31 J,电-光转换效率为0.4%,斜率效率为0.52%,激光输出能量不稳定度≤±5%,激光阈值能量为14.5 J,输出脉冲激光的中心波长在1 339.2 nm.     

Low voltage wavelength tuning of an external cavity diode laserusing a nematic liquid crystal-containing birefringent filter

A tunable diode laser incorporating a two-stage birefringent filter in an external cavity is discussed. Tuning of the laser wavelength is accomplished with a nematic liquid-crystal cell with electrically controlled birefringence in each stage of the filter. The laser has a scan range of 26.7 Å for a drive voltage to each of the liquid-crystal cells of <1.7 V RMS     

Broad range (34nm) quasi-continuous wavelength tuning insuper-structure-grating DBR lasers

The authors present super-structure-grating distributed Bragg reflector lasers that provide a quasi-continuous wavelength tuning of 34 nm with stable singlemode oscillation     

A three-electrode distributed Bragg reflector laser with 22 nm wavelength tuning range

A large wavelength tuning range is demonstrated for a three-electrode distributed Bragg reflector (DBR) laser by applying both forward and reverse bias to the passive Bragg section. In the reverse direction the tuning towards longer wavelengths is mainly attributed to electrical heating. By also using the phase tuning section, all wavelengths within a range of 22.1 nm can be reached with a side-mode suppression better than 25 dB and with an output power exceeding 4.4 mW.<>     

Erbium-doped glasses for fiber amplifiers at 1500 nm

Material-dependent properties influencing the performance of fiber amplifiers are reviewed together with the available data for Er³⁺ . The major glass types potentially useful in this application are considered and compared to silica. The topics addressed include quenching processes and the solubility of rare-earth ions, transition strengths and bandwidths at the 1500-nm gain transition, and the characteristics at the 800-, 980-, and 1480-nm pump bands. Aluminum is shown to be an extremely useful codopant for silica, improving its ability to dissolve rare-earth ions and providing desirable spectroscopic properties for Er³⁺. For some of the attributes considered, other glasses have advantages over Al silica, but only with respect to gain bandwidth and pumping performance at 800 nm is significantly better than expected from other glass compositions     

Over 1100 nm wavelength tuning in superstructure grating (SSG) DBR lasers

A broad range tuning of over 100 nm in tunable DBR lasers with superstructure grating (SSG) is reported. The SSG reflectors for 100 nm were designed and patterned by electron beam lithography. 1.55 mu m DBR lasers with SSG reflector operate in a single mode with a tuning range of 83 nm under CW conditions. With inclusion of the multimode operating region, the tuning range becomes as wide as 103 nm.<>     

高速近红外1550nm单光子探测器

高速近红外1 550 nm单光子探测器采用半导体制冷和热管风冷混合技术,雪崩二极管工作于盖革模式下,使用交流耦合方式提供门脉冲信号,通过延迟补偿和采样边沿锁存方式消除尖脉冲干扰,采用反馈门控减小后脉冲的影响。采用了ECL(Emitter Couple Logic)与TTL(Transistor-TransistorLogic)混合电子技术提高单光子探测系统的运行频率,其频率可大于10 MHz;另外,通过对雪崩信号的放大来提高信号的动态范围,进一步优化探测器的性能。实验测试与分析表明,探测器在时钟频率10 MHz、温度-62℃、门脉冲宽度8 ns的条件下的最优性能参数为:量子探测效率12.8%,暗计数率3.76×10-6ns-1,噪声等效功率8.68×10-19W/Hz1/2。     

Single grating period quantum cascade laser array with broad wavelength tuning range

A distributed feedback quantum cascade laser array emitting at λ∼ is reported. Utilising a ridge width dependence on emission wavelength, the array of laser ridges exhibited a tuning range in excess of 230 nm over the temperature range of 140 to 380 K. Singlemode operation with sidemode suppression ratios of / spl ges/25 dB and a combined tuning coefficient of -0.1 cm^-1 K^-1 are demonstrated.     

Single transverse mode operation at 1345 nm wavelength of adiode-laser pumped neodymium:ZBLAN multimode fiber laser

A diode-laser pumped multitransverse-mode neodymium-doped fluoride fiber laser is shown to oscillate in the lowest-order transverse mode when the cavity conditions are optimized. The combination of good pump coupling efficiency, laser operating efficiency, and good overlap of the HE₁₁ mode to that of a single-mode fiber, allows up to 12 mW of continuous wave (CW) power to be coupled into a standard single-mode fiber at a 1345-nm wavelength. Improved lens design should significantly increase the power injected into the single-mode fiber from the multimode fiber laser     

532nm激光距离选通成像系统

实现了一套基于532 nm波长的距离选通成像系统,并选择了几种典型环境进行了相应的原理验证实验。采用532 nm的全固态调Q脉冲激光器作为主动照明激光,激光单脉冲能量可以在35~100 mJ之间调节,系统接收望远镜口径为200 mm。采用PIN探测器获得激光脉冲发射时间,并控制目标成像的曝光时刻。成像探测器采用ICCD(intensified CCD),最小曝光时间为2 ns。通过实验对比说明该系统能够在小雨天或者有烟雾的情况下正常工作,但是获得图像的信噪比会有所下降,同时能够在强光背景干扰的环境下获得目标的图像信息。该套系统的原理验证性实验能够为距离选通成像技术的进一步发展提供重要参考。     

体光栅外腔半导体激光器列阵的光谱及调谐

对采用体布拉格光栅作为波长选择器件的外腔半导体激光列阵进行了实验研究。实验表明,在体光栅外腔作用下,高功率半导体激光器输出的线宽得到压窄、波长得到固定。与此同时,从布拉格衍射相关理论出发,分析了体光栅法线方向改变对激光器系统输出中心波长的影响。实验表明改变体光栅法线方向的角度,可以在一定范围内调整列阵的输出波长。     

选频滤波器负载外腔半导体激光器调谐特性的研究

本文分析选频滤波器负载外腔半导体激光器的调谐特性。从等效模型的受激条件出发,导出确定最大调谐范围的简单表达式,提出了计算在各种反馈强度下调谐曲线的方法,并解释近年来报道的有关实验结果。     

74 nm wavelength tuning range of an InGaAsP/InP vertical gratingassisted codirectional coupler laser with rear sampled grating reflector

A vertical-grating-assisted codirectional coupler laser with rear sampled grating reflector (GCSR laser) combines single-mode operation over a very wide tuning range of 74 nm with a side-mode suppression of better than 30 dB over most of the wavelength span. The total tuning span is limited by the combined bandwidths of the active material gain curve and the envelope of the sampled grating reflection peak spectrum, while the tuning capacity of the directional coupler filter alone is estimated to be at least 140 nm     

大功率980 nm LD-FBG多光腔组件波长锁定的研究

文章介绍了980 nm LD-FBG(激光器-光纤布拉格光栅)多光腔组件的组成和工作原理;报告了该组件在不同驱动电流和环境温度下的光谱测试结果;分析讨论了楔型耦合光纤反射率对组件光谱的影响以及波长锁定和结构优化问题.实验表明,当光功率为100~250 mW、环境温度为25~75 ℃时,优化的多光腔组件峰值波长变化＜0.6 nm,边模抑制比>45 dB.     

Packaged AlGaAs waveguide modulator array at 830 nm wavelength

We report a fully packaged AlGaAs waveguide modulator array with four individually addressable elements operating at approximately 830 nm wavelength and a clock speed of 1 GHz. The modulators rely largely on the linear electro-optic effect for operation, and have been packaged with an E/D MESFET driver with complementary 3.5 V outputs, and a thick-film ceramic bias network. The device is compact, using multimode interference devices for on-chip splitters and combiners and has a 4 mm electrode length. Extinction ratios in excess of 10 dB have been demonstrated over a temperature range from room temperature to 143°C. The modulator array has been packaged with a remote high power (100 mW) diode laser using stable single mode input coupling, while the modulator output is packaged with a multimode fiber array of 52.5 μm core diameter     

An all-solid-state broad-band frequency multiplier chain at 1500 GHz

We report the results of a high-performance all-solid-state broad-band frequency multiplier chain at 1500 GHz, which uses four cascaded planar Schottky-barrier varactor doublers. The multipliers are driven by monolithic-microwave integrated-circuit-based high electron-mobility transistor power amplifiers around 95 GHz with 100-150 mW of pump power. The design incorporates balanced doublers utilizing novel substrateless and membrane device fabrication technologies, achieving low-loss broad-band multipliers working in the terahertz range. For a drive power of approximately 100 mW in the 88-99-GHz range, the doublers achieved room-temperature peak efficiencies of approximately 30% at the 190-GHz stage, 20% at 375 GHz, 9% at 750 GHz, and 4% at the 1500-GHz stage. When the chain was cooled to 120 K, approximately 40 /spl mu/W of peak output power was measured for 100 mW of input pump power.     

Multiplexed polymer-based chirped grating lenses working at 632.8nm wavelength

A multiplexed waveguide hologram containing two off-axis chirped grating lenses working at 632.8 nm was demonstrated on a glass substrate. Focal lengths of 35 and 37 mm were experimentally confirmed. The nature of phase modulation of the holographic medium allows the formation of multiplexed waveguide lenses on the same waveguide emulsion area. The graded index (GRIN) characteristic of the guiding medium allows the formation of polymer-based photonic devices on any substrate of interest which greatly enhances the transferability of polymer based photonic integrated circuits (PICs) to various optoelectronic circuits     

10 kHz linewidth 1.5 ?m InGaAsP external cavity laser with 55 nm tuning range

An InGaAsP 1.5 ?m laser, with one facet antireflection coated, has been incorporated into a diffraction grating external cavity. The lasing wavelength could be tuned over a 55 nm range about the centre wavelength of 1.5 ?m by rotating the grating. Furthermore, it was found that the emission spectrum was extremely narrow; beat-frequency measurements at 1523 nm against an HeNe laser showed it to be of the order of 10 kHz.