Optical waveguides were fabricated at the surface of Eagle2000 glass substrates, using femtosecond laser direct writing and wet etching, and their potential as intensity-modulated refractometers was assessed. Through the analysis of their broadband spectral response to different refractive index oils, we observed that mode mismatch is present when the guided mode reaches the surface of the substrate and interacts with the external medium, thus enabling the use of such optical waveguides in refractive index sensing. Refractive indices equal to or greater than that of the substrate also induced a coupling mechanism that was shown not to be suitable in these devices. The device’s wavelength of operation was found to be tunable by controlling the distance between the surface and the center of the optical waveguide. However, the sensitivity was seen to diminish by increasing the latter, being nonexistent for distances greater than 5.5 µm. In this study, the maximum sensitivity values were found for a surface to core center distance between 1 and 2 µm, in the biological range, and 2.5 to 3 µm, for a refractive index nearing that of the substrate. Accordingly, maximum sensitivities of ≈25 dB/RIU and ≈1200 dB/RIU were found between 1.300 $<n_D^{25ºC}<$ 1.400 and 1.490 $<n_D^{25ºC}<$ 1.500, respectively.

使用飞秒激光直接写入和湿法蚀刻在Eagle2000玻璃基板的表面上制造光波导，并评估了其作为强度调制折光仪的潜力。通过分析其对不同折射率油的宽带光谱响应，我们观察到，当引导模到达基板表面并与外部介质相互作用时，会出现模不匹配，因此可以在折射率传感中使用此类光波导。等于或大于衬底的折射率也引起了耦合机制，该耦合机制被证明不适用于这些设备。通过控制光波导的表面和中心之间的距离，发现该设备的工作波长是可调的。然而，通过增加后者可以降低灵敏度，而对于大于5.5 µm的距离则不存在。在这项研究中，发现在生物学范围内，表面到核心中心距离在1到2 µm之间，对于折射率接近基板的中心，最大灵敏度值在2.5到3 µm之间。因此，发现最大灵敏度为≈25dB / RIU和≈1200dB / RIU。$<{ñ}_d^{25ºC}<$ 1.400和1.490 $<{ñ}_d^{25ºC}<$ 1.500。