多芯光纤端面上对称耦合双环微腔气体传感特性研究

Optical characteristics and vapor sensing applications of symmetrically coupled double-ring microcavities on the tip of multi-core optical fiber

光纤传感具有耐高温、抗腐蚀、无需供电、灵敏度高和可集成等优点,在光纤端面上设计制备微纳传感结构是实现探针式光纤传感器的重要途径.本文以七芯光纤端面作为平台,在其上设计了微纳波导对称耦合的双环微腔光学系统.环形微腔与微纳波导间隔一定距离,实现倏逝波耦合,波导中的光耦合进入腔内激发其高品质因子回音壁共振.当外界气体刺激改变微腔光学参数后,共振波长发生改变,从而实现对气体的传感.采用3D双光子光刻技术在多芯光纤端面上实现系统的制备.实验上观测到共振模式的品质因子最高可达2.66×10^(4),其对酒精蒸气的传感灵敏度为2.08×10^(−6)pm.

Optical fiber sensing has the advantages of high temperature resistance,corrosion resistance,power free,high sensitivity and integration.The design and fabrication of micro-nano sensing structure on the tip of optical fiber is an important way to realize the probe type optical fiber sensor.In this paper,a double ring microcavity optical system with symmetrical coupling of micro-nano waveguide is designed on the tip of seven-core optical fiber.The ring microcavity is separated from the micro-nano waveguide by a certain distance to realize the evanescent wave coupling,and the optical coupling in the waveguide enters the cavity to excite the whispering gallery modes with high quality factor.The resonance wavelength is changed when the external vapor stimulation changes the optical parameters of the microcavity,which realizes the sensing mechanism of the sensor.The system was fabricated by 3D two-photon lithography on the tip of the multi-core fiber.A resonant mode with a quality factor of 2.66×10^(4) and a sensitivity of 2.08×10^(−6) pm for alcohol vapor were obtained experimentally.