InGaAs/GaAs/AlGaAs lasers emitting at a wavelength of 1190 nm grown by MOCVD epitaxy on GaAs substrate

InGaAs/GaAs/AlGaAs laser heterostructures are grown by MOCVD epitaxy on GaAs substrates. Mesastripe laser diodes with an aperture of 100 μm emitting at a wavelength of 1190 nm are fabricated. It is shown that, in these lasers, the active region is relaxed, which manifests itself in the spread of attainable maximal power for various lasers obtained from the same heterostructure. The maximal emission power in a CW mode of lasing for such lasers was 5.5 W per mirror.     

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。     

AlGaInAs/AlGaAs SSQW GRINSCH lasers for the wavelength region between 800 and 870 nm

A semiconductor laser is proposed which has an optical active region consisting of an 8 nm thick Al/sub 0.20/Ga/sub 0.65/In/sub 0.15/As/Al/sub 0.20/Ga/sub 0.80/As strained single quantum well. The spectral emission peak of this quantum well is situated between 814 and 818 nm. The optical confinement is achieved using a standard graded refractive index separate confinement heterostructure optimised for the emission wavelength of the quantum well. Preliminary results show these lasers to have a threshold current of 18 mA.<>     

Laser compatible waveguide electroabsorption modulator with high contrast and low operating voltage in GaAs/AlGaAs

The authors demonstrate a SQW-GRINSCH ridge-waveguide electroabsorption modulator in GaAs/Al/sub x/Ga/sub 1-x/As that has a very high contrast ratio and low operating voltage and also acts as a laser with relatively low threshold current. They achieve contrast ratios of 10 dB/100 mu m of cavity length with an operating voltage of less than -4 V. In addition, when operated as laser, the device exhibits a threshold current of 25 mA. The active layer has a capacitance of 205 pF/mm/sup 2/ which would allow the fabrication of a device with a modulation bandwidth of over 20 GHz. The laser operated at a wavelength only 2-3 nm shorter than the optimum modulation wavelength.<>     

Integrated optical detector array, waveguide, and modulator based on silicon technology

An integrated optical (IO) hybrid circuit consisting of a photodetector array, waveguide, and acousto-optic modulator on a common silicon substrate has been fabricated. This IO hybrid circuit is a major step in the development of a combination optical-electronic processing system. In this device an array of p-n junction photodiodes was fabricated on a 2-in silicon wafer and a 7059 glass waveguide film sputtered over an SiO/SUB 2/ insulating layer on the wafer. Another SiO/SUB 2/ layer was deposited under the transducer electrode. The transducer was a 40-MHz lithium niobate rotated Y-cut crystal. A prism was used to couple in the light beam from a 5 mW He-Ne laser. The guided light beam was directed at one of the diodes in the array and pulsed RF signals were applied to the transducer. Oscillator frequencies of 40 MHz and 120 MHz were separately applied. Modulation depths of greater than 25 percent were produced. The fabrication of the optical guide photodiode and electrical interconnections on a single silicon wafer utilized standard IC fabrication techniques.     

短至218.3nm的可调谐激光光源

本文给出了KDP类晶体对不同波长的倍频以及和频相位匹配角的计算,从计算结果选择最佳条件做了实验验证。用脉冲Nd:YAG激光得到了最短可调谐激光波长为218.3nm。     

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。     

Enhancement in electroabsorption waveguide modulator slopeefficiency at high optical power

An increase in transfer curve slope efficiency for a Franz-Keldysh effect InGaAsP-InP electroabsorption waveguide modulator is observed as the incident optical power is increased from 5.8 to 17 dBm. However, high-frequency RF measurements agree with the gain predicted from the low-power transfer curve at all optical powers. We attribute the increase in dc slope efficiency to a temperature-induced bandgap shrinkage of the electroabsorption material     

High-efficiency GaInP-AlGaInP ridge waveguide single-mode lasersoperating at 650 nm

In this letter, the authors report a very high quantum efficiency of 91% for antireflection/high-reflection-coated GaInP-AlGaInP ridge waveguide laser diodes operating at 650 nm range. The laser structure was grown by solid-source molecular beam epitaxy. The laser diodes performed stable single-mode operation up to 60 mW. Threshold current as low as 50 mA was measured for 5.5×600 μm² laser diodes. To the authors' best knowledge, this is among the best ever reported efficiency for visible lasers     

AlGaAs/GaAs visible distributed feedback laser operating at 770 nm

A visible-light AlGaAs/GaAs DFB laser with practical characteristics oscillating at 770 nm has been fabricated by using two-step liquid phase epitaxy for the first time. Threshold current of 90 mA measured at room temperature is satisfactorily low for its simple oxide stripe structure. The same DFB mode oscillation without mode hopping has been maintained in a considerably wide range of temperature. The results show a possibility of realising a high-performance DFB laser in the visible-wavaelength region.     

High-power single mode InGaAs/AlGaAs laser diodes at 910 nm

Single mode laser diodes have been fabricated from pseudomorphic InGaAs/AlGaAs quantum well epitaxial material operating up to 350 mW CW. The laser output is a single transverse and longitudinal mode to 180 mW, while the spectral output is centred near 910 nm.<>     

Semiconductor-doped glass waveguide electro-absorption modulator

A semiconductor-doped glass optical waveguide modulator has been fabricated and characterised. Semiconductor-doped glass is a widely available material that has recently been shown to have interesting electroabsorptive properties. The work presented represents progress towards a practical switching device with significant depth of modulation.<>     

InGaAs-InP superlattice electroabsorption waveguide modulator

An electroabsorption waveguide modulator with an extinction ratio for TE-polarized light at 1550 nm of more than 20 dB for a voltage swing of less than 3 V, and low insertion losses has been realized, which exploits the Wannier-Stark effect in an InGaAs-InP short period superlattice, grown by chemical beam epitaxy. Even for a fixed voltage swing of 2.6 V, a good transmission contrast has been obtained in a wide wavelength range     

GaAlAs p-i-n junction waveguide modulator

Optical communications systems often require modulating elements which change the intensity, phase, or polarization of the light. A waveguide modulator has been fabricated in the form of a GaAlAs p-i-n heterostrueture grown on the     

The distributed feedback waveguide modulator

A novel waveguide electroabsorption modulator structure is proposed. In this structure, the resonator properties of a quarter-wave phase-shifted grating are combined with the electroabsorption properties of a multiple-quantum-well (MQW) waveguide. The theory and design considerations for such a distributed feedback MQW modulator are discussed. The performance characteristics of this structure are studied theoretically and compared with conventional MQW waveguide modulators. It is found that increased modulation bandwidth and reasonable optical bandwidths can be obtained over a device without feedback, and design tradeoffs are identified and explored     

pin硅波导在1550 nm波段的光电流雪崩增强效应实验研究

The photocurrent effect in pin silicon waveguides at 1550 nm wavelength is experimentally investigated. The photocurrent is mainly attributed to surface-state absorption,defect-state absorption and/or two-photon absorption.Experimental results show that the photocurrent is enhanced by the avalanche effect.A pin silicon waveguide with an intrinsic region width of 3.4μm and a length of 2000μm achieves a responsivity of 4.6 mA/W and an avalanche multiplication factor of about five.     

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     

High optical power electroabsorption waveguide modulator

A sampled grating distributed Bragg reflector-laser integrated with a waveguide Franz-Keldysh modulator is investigated for high optical power applications. The EAM modulation efficiency is demonstrated to asymptotically approach a limit determined by the internal differential photodetector efficiency. Linear photocurrent and 1 dB small signal AC compression point both exceed 70 mA, indicating high saturation power.     

PLZT film waveguide Mach-Zehnder electrooptic modulator

We report the numerical analysis and the fabrication of a reversed-ridge PLZT film waveguide. It is single-mode, has low transmission loss, and has large transverse cross-section suitable for efficient coupling to single-mode optical fibers. We used this structure to fabricate Mach-Zehnder (MZ) waveguide modulators. The field distribution in the channel and Y branch waveguides was calculated using a beam propagation method to analyze the modal profiles and the propagation loss. The reversed-ridge waveguides and the MZ structures were fabricated on r-sapphire substrates with a patterned ITO spacer film by sol-gel deposition. At 1.55 μm the propagation loss was 2.7 dB/cm. In the MZ, the half-wave modulation voltage was 8.5 V using 1.55 μm light and electrode length of 3.5 mm