This paper presents the development and characterization of the first fiber-integrated optical device with multifunctional capabilities of optical source, actuation, and sensing. The main component of the proposed device is a specially engineered nanoparticle (NP)-doped optical fiber with high backscattering and optical amplification features. In this case, the proposed device is based on NP-doped fiber with inscribed fiber Bragg grating (FBG) and a tapered tip subjected to a 978-nm pump. The tapered tip of the optical fiber (in conjunction with the pump below the cutoff wavelength of the optical fiber) resulted in an optical fiber tweezer for particle manipulation. In addition, the NP-doped fiber has erbium ions for optical amplification, which, in conjunction with the high scattering of such fiber, resulted in the generation of a random laser at the 1550 nm wavelength window. Such random fiber laser functionality is used in conjunction with the inscribed FBG for the sensing (and self-sensing) characteristics of the device, where the FBG acts as an edge-filter for the wavelength shift conversion to optical power variation, which enables continuous monitoring of the particle movement as a function of the tapered tip. Results show an optimal pump laser between 200 mW and 250 mW for the generation of 17 spike lines, where such a higher number of lines can enhance the sensitivity of the self-sensing functionality due to higher optical power variation. Furthermore, the optical actuation functionality demonstrated the feasibility of trapping and manipulating particles as high as 21 μm size. Finally, the self-sensing characteristics of the proposed multifunctional NP-doped optical fiber tweezer demonstrated the possibility of non-contact monitoring of particle movement with relative errors of around 2.28 μm. Therefore, the proposed approach is an unique all-in-one optical fiber device that can be readily employed not only in particles manipulation, but also in the possibility of non-contact monitoring of different dynamic structures.
