Non-polarization and high-coupling-efficiency coupler using multilevel grating structure

A multilevel grating coupler based on silicon-on-insulator (SOI) material structure is proposed to realize the coupling between waveguide and waveguide or waveguide and fiber. This coupler is compatible with the current fabrication facilities for complementary metal oxide semiconductor (CMOS) technology with vertical coupling. This structure can realize coupling when the beams with transverse electric (TE) polarization and transverse magnetic (TM) polarization are incident at the same time. The influences of the grating coupler parameters including wavelength, the thickness of waveguide layer, the thickness of SiO₂ layer and the number of steps on the TE mode and TM mode coupling efficiencies are discussed. Theory researches and simulation results indicate that the wavelength range is from 1533 nm to 1580 nm when the TE mode and TM mode coupling efficiencies are both more than 40% as the grating period is 0.99 μm. The coupling efficiencies of the incident TE and TM modes are 49.9% and 49.5% at the wavelength of 1565 nm, respectively, and the difference between them is only 0.4%.     

高功率980nm非对称宽波导半导体激光器设计

设计了980nm非对称宽波导InGaAs/InGaAsP量子阱激光器,并在结构中插入电流阻挡层,有效地阻止载流子的泄露。用LASTIP软件对980nm非对称宽波导量子阱激光器进行理论模拟,与传统的980nm对称宽波导量子阱激光器相比,非对称宽波导量子阱激光器波导和量子阱之间有更小的能带差,非对称宽波导结构具有更低的阈值电流,更高的斜效率以及更低的阻抗,所以带有电流阻挡层的980nm非对称宽波导InGaAs/InGaAsP量子阱激光器有更高的光电转换效率和输出功率。     

Design and Optimization of Electrically Injected InP-Based Microdisk Lasers Integrated on and Coupled to a SOI Waveguide Circuit

We have performed a numerical study involving the design and optimization of InP-based microdisk lasers integrated on and coupled to a nanophotonic silicon-on-insulator (SOI) waveguide circuit, fabricated through bonding technology. The theoretical model was tested by fitting it to the lasing characteristics obtained for fabricated devices, which we presented previously. A good fit was obtained using parameter values that are consistent with numerical simulation. To obtain optimized laser performance, the composition of the InP-based epitaxial layer structure was optimized to minimize internal optical loss for a structure compatible with efficient current injection. Specific attention was paid to a tunnel-junction based approach. Bending loss was quantified to estimate the minimum microdisk diameter. The coupling between the InP microdisk and Si waveguide was calculated as function of the bonding layer thickness, waveguide offset and waveguide width. To study the lateral injection efficiency, an equivalent electrical network was solved and the voltage-current characteristic was calculated. Based on these results, the dominant device parameters were identified, including microdisk thickness and radius, coupling loss and tunnel-junction p-type doping. These parameters were optimized to obtain maximum wall-plug efficiency, for output powers in the range 1-100 W. The results of this optimization illustrate the potential for substantial improvement in laser performance.     

大功率小垂直发散角980nm量子阱激光器

提出了一种新型非对称宽耦合波导结构,通过理论计算优化了结构中n型波导层和限制层厚度,并采用低压金属有机化学气相沉积方法生长了设计的器件结构.测试了器件的光电特性,1200μm腔长器件的阈值电流为590 mA,斜率效率为0.96 w/A,最大输出功率达2000mW;当注入电流为0.6 A时,其远场发散角为16.1°(θ⊥)×10.2°(θ//).实验结果表明:新型非对称宽耦合波导结构能实现器件大功率输出,有效减小器件远场垂直发散角,改善器件光束质量.     

High power 980 nm ridge waveguide lasers with etch-stop layer

For the first time, the use of an etch-stop layer to precisely control the mesa height in ridge waveguide InGaAs/GaAs lasers is reported. These 980 nm devices emit up to 180 mW of total power in the fundamental spatial mode and lase in a single frequency with sidemode suppression ratios of greater than 25 dB.<>     

Wavelength-graded horizontal cavity laser array with postgrowthadjustment of wavelength

Wavelength-graded emission from a visible red GaInP-AlGaInP laser diode array has been achieved with the contradirectional surface-mode coupling technique. The wavelength control is attained by postgrowth adjustment of the thickness of the surface waveguide. The horizontal cavity lasers show both edge and surface emission (beam divergence 0.12°). The thermal red-shift of the wavelength is 0.028±0.002 nm/K. They show single-mode emission with a typical spectral linewidth of 0.09 nm and a sidemode suppression ratio up to 29 dB. The wavelength spacing between the individual lasers is 0.76±0.08 nm yielding a total range across the array of 5.4 nm (from 681.5 to 686.9 nm)     

Performance of Hybrid Laser Diodes Consisting of Silicon Slab and InP/InGaAsP Deep‐Ridge Waveguides

The fundamental transverse mode lasing of a hybrid laser diode is a prerequisite for efficient coupling to a single‐mode silicon waveguide, which is necessary for a wavelength‐division multiplexing silicon interconnection. We investigate the lasing mode profile for a hybrid laser diode consisting of silicon slab and InP/InGaAsP deep ridge waveguides. When the thickness of the top silicon is 220 nm, the fundamental transverse mode is lasing in spite of the wide waveguide width of 3.7µm. The threshold current is 40 mA, and the maximum output power is 5 mW under CW current operation. In the case of a thick top silicon layer (1 µm), the higher modes are lasing. There is no significant difference in the thermal resistance of the two devices.     

Directional light output from photonic-wire microcavity semiconductor lasers

We have obtained directional light output from a recently realized InGaAsP photonic-wire microcavity ring lasers. The output was achieved by fabricating a 0.45-/spl mu/m-wide U-shape waveguide next to a 10-/spl mu/m diameter microcavity ring laser. The laser has a threshold pump power of around 124 /spl mu/W when optically pumped at 514 nm. It is comparable to the former structure without output coupling. The output coupling efficiency can be controlled carefully by choosing the spacing between the laser cavity and the waveguide.     

玻璃平面波导的热键合制备与界面扩散研究

铒镱共掺磷酸盐玻璃平面波导在散热和抑制非线性效应方面具有独特优势,可开发作为近红外1.5 μm高平均功率固体激光器的增益介质,具有重要意义。文中应用光胶热键合方法制备铒镱共掺磷酸盐玻璃平面波导,研究了预键合阶梯升温过程对键合质量的影响。通过电子探针表面分析（EPMA）得到键合温度和键合时间对键合界面分子扩散层厚度的影响,并根据Fick第二定律,探讨了一维等效假设下的芯层玻璃中的Yb3+扩散机理,建立了热键合过程中的固-固界面分子扩散模型。最终通过选择最优的热处理工艺参数,得到了键合质量良好且键合强度达到11.63 MPa的芯层厚度为100 μm的三明治结构平面波导。     

900nm三叠层隧道级联激光器的结构优化研究

采用金属有机化合物气相淀积方法生长了900nm的三叠层隧道级联激光器。针对隧道级联激光器存在工作电压高、材料各层的光场耦合等问题,分别采用δ掺杂、扩展波导等技术对激光器结构进行了优化,并通过模拟计算对隧道结耗尽区宽度进行了优化。通过优化隧道结δ掺杂的生长条件,得到n+GaAs的掺杂浓度大于1×1019/cm3,使工作电压下降1V;通过采用扩展波导,使垂直发散角由常规结构的35°减小到20°。将900nm的三叠层隧道级联激光器制作成条宽300μm、腔长800μm的条形激光器,采用同轴封装形式,在20A的脉冲工作电流下,输出功率达到55W,斜率效率达到2.9W/A,以上指标是普通激光器的3倍。     

A Hybrid AlGaInAs–Silicon Evanescent Amplifier

We report a hybrid AlGaInAs-silicon evanescent amplifier incorporating a silicon waveguide with a III-V gain medium. The optical mode of the hybrid amplifier is mostly confined to the silicon waveguide and evanescently coupled to the AlGaInAs quantum-well (QW) region where optical gain is provided by electrical current injection. These two different material systems are bonded by low-temperature oxygen plasma assisted wafer bonding at 300 degC. The fabricated device shows 13 dB of maximum chip gain with 11 dBm of output saturation power. Evanescent coupling allows a lower active region confinement factor to provide a higher saturation output power than amplifiers with centered QWs, which is important for applications that require linear amplification     

Operating Characteristics of Semiconductor Quantum Well Lasers as Functions of the Waveguide Region Thickness

The performance characteristics of semiconductor lasers based on quantum wells (QWs) are theoretically studied as functions of the thickness of the waveguide region [optical confinement layer (OCL)]. The maximum modal gain, optical-confinement factor (in QWs, OCLs, and emitters), threshold current density, electron and hole densities (in QWs and OCLs), internal optical loss (in QWs, OCLs, and cladding layers), internal differential quantum efficiency, currents of stimulated and spontaneous recombination and the output optical power of the laser are calculated as functions of the OCL thickness. It is shown that up to pump current densities of 50 kA/cm² the dependence of the output power of the considered lasers on the OCL thickness is weak in the thickness range of 1.5–2.8 μm. This result is important for the development of high-brightness lasers, since such lasers use a wide waveguide to ensure low radiation divergence. It is shown that, at very high pump-current densities, the output power has a maximum as a function of the OCL width.

     

InGaAs/GaAs/AlGaAs应变量子阱激光器

优化设计了既能实现较小垂直方向远场发散角,又能降低腔面光功率密度的ＩｎＧａＡｓ／ＧａＡｓ／ＡｌＧａＡｓ应变层量子阱激光器,并计算了该结构激光器实现基横模工作的脊形波导结构参数。利用分子束外延生长了ＩｎＧａＡｓ／ＧａＡｓ／ＡｌＧａＡｓ应变量子阱激光器材料并研制出基横模输出功率大于１４０ｍＷ,激射波长为９８０ｎｍ的脊形波导应变量子阱激光器,其微分量子效率为０．８Ｗ／Ａ,垂直和平行结平面方向远场发散角分别为２８°和６．８°     

基于silica波导光栅的单纤三向器的混合集成研究

通过有源实时监控系统,采用手动和自动相结合的方法,将光纤、silica基阵列波导光栅(AWG)、1310nm激光器(LD)平台和1490nm、1550nm探测器(PD)平台用紫外固化胶混合集成为一新型单纤三向器。在耦合集成过程中,LD在15mA偏置电流下,三向器的上行出纤功率大约为-4dBm,LD和波导的耦合效率大约40%;当三向器输入1550nm光功率为1mW,PD在2.6V反向偏压下,下行输出光电流大约为76μA,波导和PD的耦合效率大约为42%。三向器中采用了对管PD集成方法。     

A 980 nm pseudomorphic single quantum well laser for pumpingerbium-doped optical fiber amplifiers

The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22% coupling efficiency into as 1.55-μm single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er³⁺-doped fiber amplifiers     

掺铒铌酸锂调Q激光器的设计和分析

本文设计了用Mach-Zehnder干涉型调制开关作为调Q开关的掺铒铌酸锂（Er:LiNbO3）调Q波导激光器,并进行分析。发现激光器输出功率可达1.5kW以上;比较了泵浦光波长为980nm和1480nm时的输出功率和脉冲宽度的情况,研究了腔长变化对激光器输出特性的影响,发现用1480nm光泵浦时阈值较低,但用980nm光泵浦能得到更高的峰值功率和更窄的脉冲宽度。     

High power GaInP/AlGaInP visible lasers (/spl lambda/=646 nm) with narrow circular shaped far-field pattern

GaInP/AlGaInP visible lasers based on a longitudinal photonic bandgap crystal waveguide emitting at 646 nm show narrow circular shaped far field pattern. Vertical and lateral beam divergence of about 8/spl deg/ (full width at half maximum) that is independent of injection current is demonstrated. Differential quantum efficiency is up to 85%. Pulsed total optical output power is as high as 20 W for 100 /spl mu/m-wide stripe lasers and 6 W for 20 /spl mu/m-wide stripe lasers. Such values of output optical power are 2.5 higher with respect to ones obtained for the lasers fabricated from the state-of-the-art epiwafers for commercial 650 nm range DVD lasers.     

Research progress of III-V laser bonding to Si

The vigorous development of silicon photonics makes a silicon-based light source essential for optoelectronics'' integration. Bonding of III-V/Si hybrid laser has developed rapidly in the last ten years. In the tireless efforts of researchers, we are privileged to see these bonding methods, such as direct bonding, medium adhesive bonding and low temperature eutectic bonding. They have been developed and applied to the research and fabrication of III-V/Si hybrid lasers. Some research groups have made remarkable progress. Tanabe Katsuaki of Tokyo University successfully implemented a silicon-based InAs/GaAs quantum dot laser with direct bonding method in 2012. They have bonded the InAs/GaAs quantum dot laser to the silicon substrate and the silicon ridge waveguide, respectively. The threshold current of the device is as low as 200 A/cm². Stevan Stanković and Sui Shaoshuai successfully produced a variety of hybrid III-V/Si laser with the method of BCB bonding, respectively. BCB has high light transmittance and it can provide high bonding strength. Researchers of Tokyo University and Peking University have realized III-V/Si hybrid lasers with metal bonding method. We describe the progress in the fabrication of III-V/Si hybrid lasers with bonding methods by various research groups in recent years. The advantages and disadvantages of these methods are presented. We also introduce the progress of the growth of III-V epitaxial layer on silicon substrate, which is also a promising method to realize silicon-based light source. I hope that readers can have a general understanding of this field from this article and we can attract more researchers to focus on the study in this field.     

Room-temperature continuous-wave operation of type-I GaSb-based lasers at 3.1 μm

Type-I interband lasers on GaSb were grown by molecular beam epitaxy using 16 nm InGaAsSb compressively-strained quantum wells (QWs) with 30 nm AlInGaAsSb quinary barriers for improved hole confinement. The 3QW active regions were embedded in standard AlGaAsSb waveguides to limit the thickness of quinary material owing to its low growth temperature requirements. In continuous-wave operation, a typical ridge waveguide laser (width 10 mum, length 1214 mum) produced 6 mW total output power at 20degC with a threshold current of 140 mA. The temperature sensitivity of the devices remains a challenge, as evidenced by the dramatically improved performance at 0degC (16 mW total output power, threshold current 74 mA).     

Erbium-doped ion-exchanged waveguide lasers in BK-7 glass

Ion-exchange in glass is a simple, flexible technique to realize optical fiber-compatible planar waveguide devices. Recently, neodymium-doped waveguide lasers operating at 1060 and 1300 nm have been demonstrated in this technology. Lasers operating at 1540 nm are desirable for telecommunication applications and the authors report for the first time ion-exchanged waveguide lasers in erbium-doped glass emitting at this wavelength. Lasers in BK-7 glass doped with 0.5 wt.% Er ₂O₃ and pumped at 980 nm exhibited launched pump power thresholds of 150 mW and slope efficiencies of 0.55%. The waveguides operated in a single transverse mode at the lasing wavelength