A new method for fabricating low-cost, high-performance waveguides, lasers and modulators in photonic integrated circuits for optical communication networks

职务名称：一种在光通信网络的光子集成电路中制造低成本、高性能波导、激光器和调制器的新方法。将多个光波器件（如激光器和光调制器）集成到单个芯片上的复杂、高功能配置中，称为光子集成电路（PIC），可以大大降低支持互联网和电信的高速光网络系统的成本，类似于硅集成电路提供的电子和计算方面的进步。 然而，当前的集成技术需要昂贵的晶体再生长工艺，由于现在使用的材料的物理性质而面临基本的速度限制，并且使用电子束光刻方法（不能扩展到大规模制造）以实现最佳性能所需的小波导尺寸。 该项目支持一种新的低成本波导制造方法的研究，该方法可以解决当前的每一个不足，从而有望显着提高未来先进光子集成电路的调制器和激光器的集成水平和性能。 这种PIC将使低成本的光通信系统，并增加宽带互联网的部署，以服务不足的人口areas.The具体目标的研究是开发一种独特的，新的选择性波导芯氧化工艺的AlInGaAs/InP材料系统用于双波长光子器件。 一种新的氧增强的湿热氧化工艺将优化这种新的材料系统和由此产生的低折射率，低介电常数，绝缘，界面钝化，和粗糙度平滑的埋氧层的好处充分利用高速电吸收调制器（EAM）和激光器件的制造。 该工艺允许将整个波导芯宽度减小到单模尺寸，而不需要电子束光刻。低介电常数提供了减小的寄生电容和强的光学限制，而不会引起接触电阻的增加，从而减小了整体RC时间常数，以实现高调制速度器件。 氧化物承诺同时大大降低界面粗糙度和波导散射损耗，并修复干法刻蚀离子损伤。所得到的高折射率对比度波导结构使得基于InP的1.3和1.55微米电信波长器件具有稳定的光学空间模式限制，该光学空间模式限制可以以低弯曲损耗积极地弯曲，用于光学信号路由和适合于密集封装的光子集成电路的片上激光器。 将使用的研究方法包括优化氧化系统气流动力学，以提高工艺控制和氧化物均匀性;表征和优化氧化物绝缘性能、折射率和热导率;时间分辨光致发光，以表征氧化物-半导体界面质量;精密角度抛光和聚焦离子束铣削，以检查掩埋氧化物界面粗糙度;和扫描激光法布里-珀罗传输谐振波导损耗测量。 三个有针对性的氧化物限制的AlInGaAs/InP器件的应用将探讨与廷德尔国家研究所在科克，爱尔兰合作：高速行波电吸收调制器;高速直接调制激光器;和紧凑，弯曲谐振器片上集成激光器利用低弯曲损耗性能的建议独特的氧化物限制波导结构。

Title: A new method for fabricating low-cost, high-performance waveguides, lasers and modulators in photonic integrated circuits for optical communication networks.The integration of multiple lightwave devices such as lasers and optical modulators into a complex, highly functional configuration on a single chip, known as a photonic integrated circuit (PIC), can dramatically reduce the cost of high-speed optical networking systems supporting the internet and telecommunications, akin to advances in electronics and computing offered by silicon integrated circuits. However, current integration technologies require expensive crystal regrowth processes, face fundamental speed limitations due to the physical properties of the materials now in use, and use electron beam lithography methods (not scalable to mass manufacturing) in order to achieve the small waveguide dimensions needed for optimal performance. This project supports research on a new low-cost waveguide fabrication method that addresses each of these current shortfalls which promises to significantly enhance the integration level and performance of modulators and lasers for the advanced photonic integrated circuits of the future. Such PICs will enable lower cost optical communications systems and increase the deployment of broadband internet to underserved population areas.The specific goals of this research are to develop a unique, new selective waveguide core oxidation process for the AlInGaAs/InP material system used for telecommunication-wavelength photonic devices. A novel oxygen-enhanced wet thermal oxidation process will be optimized for this new material system and the benefits of the resulting low-refractive-index, low dielectric-constant, insulating, interface-passivating, and roughness-smoothing buried oxide layer fully exploited for the fabrication of high-speed electro-absorption modulator (EAM) and laser devices. The process allows the overall waveguide core width to be reduced to single-mode dimensions without the need for e-beam lithography. The low dielectric constant offers reduced parasitic capacitance and strong optical confinement without incurring increased contact resistance, thus reducing the overall RC time constant to achieve high modulation speed devices. The oxide promises to simultaneously dramatically reduce interface roughness and waveguide scattering loss and remediate dry-etch ion damage. The resulting high-index-contrast waveguide structure enables InP-based 1.3 and 1.55 micron telecomm wavelength devices with stable optical spatial mode confinement that can be aggressively curved with low bend loss for optical signal routing and on-chip lasers suitable for densely-packed photonic integrated circuits. Research methods to be used include optimization of oxidation system gas flow dynamics to enhance process control and oxide uniformity; characterization and optimization of oxide insulating properties, refractive index, and thermal conductivity; time-resolved photoluminescence to characterize oxide-semiconductor interface quality; precision angle polishing and focused ion beam milling for inspection of buried-oxide interface roughness; and swept-laser Fabry-Perot transmission resonance waveguide loss measurements. Three targeted oxide-confined AlInGaAs/InP device applications will be explored in collaboration with the Tyndall National Institute in Cork, Ireland: high-speed traveling-wave electro-absorption modulators; high-speed directly-modulated lasers; and compact, curved-resonator on-chip integrated lasers exploiting the low-bend loss properties of the proposed unique oxide-confined waveguiding structure.