Low Loss Splicing And Applications Of Optical Micro/Nanowires In Photonic Devices

Following the trends of miniaturization and integration of photonic devices, the fabrication and application of micro/nano-photonic devices have become important topics in the field of photonics. As elementary components of micro/nano-photonic devices, optical micro/nanowires possess the advantages of effective confinement of light, low loss and strong evanescent field, and have been used to construct many kinds of interferometers, resonators and lasers. But so far, most of the photonic devices based on optical micro/nanowires are maintained by substrate-supported friction or van der Waals attraction with inadequate robustness, which are unfavorable for practical application of microphotonic devices. In this work, we propose a novel approach to splicing optical micro/nanowires via polymer nanowires. The optical loss, mechanical strength and thermal stability of the spliced area are studied, and several kinds of passive and active microphotonic devices are assembled by the splicing method.In the first part of this work, we demonstrate the implementation of the polymer splicing technique and characterize the performances of the as-formed spliced area. Experimental results show that the spliced area has relatively high mechanical strength and good thermal stability, with additional optical loss down to0.51dB for a single splicing around the1550nm wavelength. Compared with other splicing approaches, this technique is quite simple and independent of the micro/nanowire material, and therefore represents a general approach.In the second part of this work, we demonstrate several functional optical components assembled via polymer splicing, including a microfiber ring resonator, a Mach-Zehnder interferometer, and a Sagnac loop mirror. The devices are evaluated in air and/or in water, showing high robustness and good performances. While maintaining the pre-splicing performances of the devices, the splicing technique yields pretty small and controllable splicing area, and markedly improves the flexibility and stability of the devices under complicated environments.In the third part of this work, we demonstrate a freestanding CdS nanowire ring laser, fabricated by the polymer splicing technique. The lasing spectra and thresholds of nanowire lasers in the forms of open-loop, closed-loop, and spliced-loop are compared, in which spliced-loop nanowire ring shows excellent cavity resonance and relatively low lasing threshold. Moreover, the spliced ring laser can be transferred to and still operated well in liquid environment, and is robust enough to resist a certain amount of deformation.The polymer splicing technique demonstrated in this work releases microphotonic devices based on micro/nanowires from the starting substrate, and broadens the scopes of applications to much wider circumstances, and can be applied to almost all kinds of micro/nanowires, showing certain significance for the research and technological applications of microphotonic device.