Lijing Zhong, Zakoldaev Roman A, Sergeev Maksim M, Petrov Andrey B, Veiko Vadim P, Alodjants Alexander P
Faculty of Laser Photonics and Optoelectronics, ITMO University, 197101 Saint Petersburg, Russia.
School of Optical and Electronic Information, Huazhong University of Science & Technology, Luoyu Road 1037, Wuhan 430074, China.
Nanomaterials (Basel). 2021 Jan 7;11(1):123. doi: 10.3390/nano11010123.
Laser direct writing technique in glass is a powerful tool for various waveguides' fabrication that highly develop the element base for designing photonic devices. We apply this technique to fabricate waveguides in porous glass (PG). Nanoporous optical materials for the inscription can elevate the sensing ability of such waveguides to higher standards. The waveguides were fabricated by a single-scan approach with femtosecond laser pulses in the densification mode, which resulted in the formation of a core and cladding. Experimental studies revealed three types of waveguides and quantified the refractive index contrast (up to Δn = 1.2·10) accompanied with ~1.2 dB/cm insertion losses. The waveguides demonstrated the sensitivity to small objects captured by the nanoporous framework. We noticed that the deposited ethanol molecules (3 µL) on the PG surface influence the waveguide optical properties indicating the penetration of the molecule to its cladding. Continuous monitoring of the output near field intensity distribution allowed us to determine the response time (6 s) of the waveguide buried at 400 µm below the glass surface. We found that the minimum distinguishable change of the refractive index contrast is 2 × 10. The results obtained pave the way to consider the waveguides inscribed into PG as primary transducers for sensor applications.
玻璃中的激光直写技术是制造各种波导的有力工具，极大地拓展了光子器件设计的元件基础。我们应用该技术在多孔玻璃（PG）中制造波导。用于刻写的纳米多孔光学材料可将此类波导的传感能力提升至更高水平。这些波导是通过飞秒激光脉冲以致密化模式的单扫描方法制造的，从而形成了芯层和包层。实验研究揭示了三种类型的波导，并量化了伴随约1.2 dB/cm插入损耗的折射率对比度（高达Δn = 1.2·10）。这些波导展示了对纳米多孔框架捕获的小物体的敏感性。我们注意到，沉积在PG表面的乙醇分子（3 µL）会影响波导的光学特性，这表明分子渗透到了其包层中。对输出近场强度分布的连续监测使我们能够确定埋在玻璃表面以下400 µm处的波导的响应时间（6 s）。我们发现折射率对比度的最小可分辨变化为2×10。所获得的结果为将刻写在PG中的波导视为传感器应用的主要换能器铺平了道路。
