铌酸锂有源光子线

Si photonics is established on the basis of silicon-on-insulator (SOI) photonic wire (PW). It is of great potential in the field of high-density modern integrated optics and is currently an international hot research field.. However, the research and development of relevant active devices based on the SOI-PW suffers from two aspects of serious intrinsic problems, i. e., great background absorption of silicon material itself and poor spectroscopic properties of doped active ions as well. It is therefore imperative to explore other feasible ways for developing highly efficient ultra-compact micro-photonic active devices. Based on that the applicant and his co-workers have been working on LiNbO3 (LN)-based optical waveguide devices over the past years, present project proposes to develop photorefractive-damage-resistant active photonic wire based on Er3+/Zr4+-codoped submicron thick near-stoichiometric (NS) LN thin film on insulator (LNOI). The main objective is to explore and develop a feasible technology to fabricate high-quality rare-earth-doped active LNOI-PW with low-loss and high resistance to photorefractive damage, from which the LN crystal suffers. The technology enables to find a feasible way and establish a technical supporting platform for the development of various highly efficient ultra-compact micro-photonic active devices. The research emphasizes on fabrication and characterization of NS Zr:Er:LNOI PW and amplifier. The main contents of research include (1) suggesting the strategy for developing an active LNOI-PW, (2) carrying out an overall characterization for the properties of the active LNOI-PW developed, (3) solving some crucial technical issues with regard to the active LNOI-PW fabrication, and (4) exemplifying to develop an optical amplifier so as to examine the applicability of the photorefractive-damage-resistant active LNOI-PW developed. The project proposed not only possesses solid ground and good continuity of research work, but also belongs to the pioneering work and is quite challenging. The outputs of the project are of crucial significance to the development of the high-density modern integrated optics, as well as in driving and accelerating the commercial applications and utilization of the LN-based waveguide devices.

硅光子学建立在硅光子线基础之上，在高密度集成光学领域具有巨大的发展潜力，是当今国际热点研究领域。但硅光子线有源器件的研发受困于硅材料巨大背景吸收以及所掺入的激光离子光谱特性较差。探索其它途径研发高效微光子有源器件势在必行。基于过去一直从事铌酸锂(LN)导波器件研究工作本项目提出研制基于铒、锆共掺亚微米厚LN薄膜的抗光折变有源光子线(LNOI-PW)。主要研究目标是探索研究并建立可行的技术用于制作低损耗、高抗光折变能力的有源LNOI-PW，为研发各种高效超紧凑微光子线有源器件探索出一条可行的途径并建立技术支撑平台。研究内容包括有源LNOI-PW制作战略、性能表征、一些关键技术问题，举例研发一光子线放大器以考察其可应用性。本研究项目不但具有良好研究工作基础和连续性，而且属于先驱性研究工作并富有挑战性。所取得研究成果对高密度集成光学的发展和推动LN光波导器件向实用化阶段迈进均具有重要的意义。

本项目提出研制亚微米厚铒掺杂LN薄膜和有源光子线(LNOI-PW)。主要研究结果包括如下几方面：.(1) 采用离子切削内嵌有窄条钛扩散层的NS Zr:Er:LN薄膜（战略A）以及首先离子切削NS Zr:Er:LN薄膜然后再进行光刻和软质子交换（战略B）两种战略制作出了稀土掺杂抗光折变有源LNOI光子线。还尝试了采用由Czochalski提拉法生长出的体掺铒铌酸锂晶体作为起始材料，采用氦离子束切削、化学机械抛光和晶片键合相结合的方法制作铒离子掺杂的Er:LNOI薄膜，并取得了成功。与上述两种制备战略A和B相比，该方法具有制作简单、成功率高和实用优点。.(2) 采用电子束曝光、反应离子刻蚀以及化学机械抛光技术相结合的方法在Er3+掺杂LNOI表面成功研制出了脊型光子线。.(3) 对所制作出的Er:LNOI薄膜和有源光子线进行全面、系统表征，包括光子线的形貌、晶相、组份、NS Zr:Er:LNOI薄膜厚度与He+离子注入能量关系、光子线内铒离子光谱性质、导波特性(包括模式特性、损耗，模场分布)、光折变性质、扩散离子浓度在光子线中的分布特征以及在光子线截面的二维折射率分布。.(4) 着重表征了光子线分别在980纳米和1480纳米波长泵浦下对1.53微米小信号的放大性能。结果显示：在980纳米泵浦功率仅为21毫瓦下，5毫米长微光子放大器的小信号片上增益可达5 dB，增益系数达10 dB/cm, 较传统Ti扩散Er:LN条形波导放大器的饱和增益系数提高了五倍。此外，由于光子线内超高的光子密度，该放大器具有超低的阈值泵浦功率<1 mW, 比传统Ti扩散Er:LN条形波导放大器低一个数量级。如此超高效的片上放大性能充分显示了其巨大的片上应用前景。.(5) 同步开展了光子线放大性能的仿真研究。获得了大量有参考价值的数值结果，为高效微光子线放大器的制作提供了理论依据。.本研究项目建立了一可行的技术用于制作低损耗、高抗光折变能力的有源LNOI-PW，实现了预期研究目标，为研发各种高效超紧凑微光子线有源器件探索出一条可行的途径并建立技术支撑平台。所取得研究成果对高密度集成光学的发展和推动LN光波导器件向实用化阶段迈进均具有重要的意义。此外，进一步加强了天津大学和香港城市大学之间的合作。