Packaged silica microsphere-taper coupling system for robust thermal sensing application

Abstract

We propose and realize a novel packaged microsphere-taper coupling structure (PMTCS) with a high quality factor (Q) up to 5×10(6) by using the low refractive index (RI) ultraviolet (UV) glue as the coating material. The optical loss of the PMTCS is analyzed experimentally and theoretically, which indicate that the Q is limited by the glue absorption and the radiation loss. Moreover, to verify the practicability of the PMTCS, thermal sensing experiments are carried out, showing the excellent convenience and anti-jamming ability of the PMTCS with a high temperature resolution of 1.1×10(-3) ◦C. The experiments also demonstrate that the PMTCS holds predominant advantages, such as the robustness, mobility, isolation, and the PMTCS can maintain the high Q for a long time. The above advantages make the PMTCS strikingly attractive and potential in the fiber-integrated sensors and laser.

High-Q silk fibroin whispering gallery microresonator

“…The resulting device has a thermal response with a measured sensitivity of -1.17 nm/K (circle points in Fig. 4), which is about 8 times what was previously reported in WGM thermal sensor [21][22][23][24].…”

“…Furthermore, we have demonstrated thermal sensing based on silk fibroin microtoroid with the sensitivity as high as 1.17 nm/K, which is about 8 times higher than the previous WGM resonator based thermal sensors [21][22][23][24]. The high sensitivity of the silk resonator based thermal sensor originates from the large thermal expansion coefficient [25], which is three order of magnitude larger than that of silica.…”

Theory of free space coupling to high-Q whispering gallery modes

“…It is taken for granted that free space coupling to WGMs is very inefficient since the radiation loss of circular shaped microcavity is isotropic and low, which brings the difficulty of energy transference between outside and WGMs. Near field couplers, such as prism [16], fiber taper [17,18] and perpendicular waveguide [19], enable high efficient excitations and collections to microresonators. Therefore, these near field couplers are widely adapted in experiments.…”

A Packaged Whispering Gallery Mode Strain Sensor Based on a Polymer-Wire Cylindrical Micro Resonator

“…Yan et al [27] and Wang et al [28] demonstrated a packaging method for a tapered fiber-coupled spherical micro resonator utilizing low refractive index UV curable glue as the coating material. The authors also carried out temperature and photosensitivity studies to evaluate the device performance after packaging.…”