The typical functions of the optical fiber are communication and sensing. However, the fiber functions need to extend to meet the requirements of the development of artificial intelligence. This paper achieves an all-fiber device with storage and logic computing functions using a single-mode fiber and Ge2Sb2Te5 (GST) material. We use the pulse amplitude modulation (the switching energy is about 50 nJ) to switch the GST state for performing the eight-level data storage (3-bit). The all-fiber memory device has the advantages of high optical contrast (about 38%), good reversibility, and high repeatability. We implement the all-optical logic operations (“AND” and “OR”) by using two memory cells in series and parallel. For the first time, we use the single-mode optical fiber to realize storage and computing functions, and this intelligent fiber has tremendous application potential in intelligent optical fiber communication and portends a new paradigm for brain-like computing.

A multi-focus optical fiber lens is numerically demonstrated based on an all-dielectric metasurface structure. The metasurface consists of an array of rectangular silicon resonators with varying widths in order to obtain the required phase distribution. The core diameter of the multimode fiber is large enough to contain sufficient resonance units. The spatial distribution of the dielectric resonators is dictated by spatial multiplexing, including interleaving meta-atoms and lens aperture division, to achieve multi-focus properties. The proposed optical fiber metalens can produce two or three focal points along the longitudinal direction with high focusing efficiency. The size of every focal point is close to the diffraction limit, and the relative intensity on each focus can be controlled by adjusting the number of the respective resonators. The proposed optical fiber lens will have a great potential in the fields of integrated optics and multifunctional micro/nano devices.

Light is a precious resource that nature has given to human beings. Converting green, recyclable light energy into the mechanical energy of a micromotor is undoubtedly an exciting challenge. However, the performance of current light-induced micromotor devices is unsatisfactory, as the light-to-work conversion efficiency is only 10?15–10?12. In this paper, we propose and demonstrate a laser-induced rotary micromotor operated by Δα-type photopheresis in pure liquid glycerol, whose energy conversion ratio reaches as high as 10?9, which is 3–6 orders of magnitude higher than that of previous light-induced micromotor devices. In addition, we operate the micromotor neither with a light field carrying angular momentum nor with a rotor with a special rotating symmetrical shape. We just employ an annular-core fiber to configure a conical-shaped light field and select a piece of graphite sheet (with an irregular shape) as the micro-rotor. The Δα-type photophoretic force introduced by the conical-shaped light field drives the rotation of the graphite sheet. We achieve a rotation rate up to 818.2 r/min, which can be controlled by tuning the incident laser power. This optical rotary micromotor is available for twisting macromolecules or generating vortex and shear force in a medium at the nanoscale.

We propose and demonstrate a dual-channel microfluidic sensor based on a side-hole fiber (SHF) with two long-period fiber grating (LPFG) structures. There are two air holes in the SHF, which are natural microfluidic channels. We fabricate two LPFGs (long-period gratings LPG-A and LPG-B) in the SHF with the resonance wavelengths of 1268.7 nm and 1385.8 nm, respectively. Results show that the refractive index sensitivities of LPG-A and LPG-B are ?76.0 nm/RIU and ?71.1 nm/RIU, respectively. One can measure the refractive index of liquid samples in two channels simultaneously. The proposed dual-channel microfluidic sensor has advantages of good linearity response, fluidic technology compatibility, and easy light input/output coupling and system integration, which helps the sensor to have a potential application in environmental detection and food safety detection.

We propose and demonstrate single fiber dual-functionality optical tweezers based on a graded-index multimode fiber. By using the multi-angle fiber grinding and polishing technology, we fabricate the multimode fiber tip to be a special tapered shape, contributing to focus the outgoing beam with a large intensity gradient for the first functionality—three-dimensional contactless trapping of a microparticle. By adjusting the radial direction offset between the lead-in single mode fiber and the graded-index multimode fiber, we perform the second functionality—axial shift of the trapped microparticle with respect to the fiber tip without need of moving the fiber probe itself. It is convenient for practical applications. The theoretical and experimental results about the relationship between the radial offset and the equilibrium positions of the microparticle have the good consistency. Tailoring the trap and axial shift of the microparticle based on the graded-index multimode fiber provides convenient avenues for fiber optical tweezers applied in practical researches.

In-fiber integrated optics is an attempt to use silica fiber as a substrate, integrating various optical paths or optical components into a single fiber, to build a functional optical device or component, and to realize a micro optical system, achieving various functions. In-fiber integrated optics is expected to be a new branch of photonics integration. This integration technique enables convenient light beams control and manipulation inside in one fiber. It also provides a research platform with micro and nano scale for interaction between light wave and microfluidic materials. In this review, we briefly summarize the main ideas and key technologies of the in-fiber integrated optics by series integration examples.

We propose and demonstrate a novel single fiber optical tweezer based on a graded-index multimode fiber (GIMMF), which works with a free length GIMMF (>30 cm). We achieve a three-dimensional stable trap of yeast cells by using the GIMMF optical tweezers. Compared with the single-mode fiber optical tweezers, the GIMMF optical tweezers possess large optical trapping forces. Owing to the freedom of the GIMMF length, the fabrication of the GIMMF optical tweezers is simple, repeatable, and highly efficient. The GIMMF tweezers have the penitential to become a new member of the single fiber optical tweezers family and have a wide range of applications in the medical and biological cytology fields.

We propose an ultra-simple dual-channel configuration for simultaneously evaluating two branches of a multifunctional integrated optic chip (MFIOC). In the configuration, the MFIOC is employed as a beam splitter to construct the demodulation interferometer together with a 2 × 2 fiber coupler. Interference happens between polarization modes traveling through different channels of the MFIOC. The cross-couplings of each channel are respectively characterized by the interference peaks which distribute on opposite sides of the central interference peak. Temperature responses of the MFIOC are experimentally measured from ?40°C to 80°C. Results show that the proposed configuration can achieve simultaneous dual-channel transient measurements with resolution of ?90 dB and dynamic range of 90 dB. In addition, the two channels of the configuration have consistent measuring performance, and the two branches of the MFIOC have different responses to temperature variation.