Single fiber dual-functionality optical tweezers based on graded-index multimode fiber

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 a~）Dlied in practical researches.

Intelligent all-fiber device: storage and logic computing

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 Ge_(2)Sb_(2)Te_(5)(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.

Dual-channel microfluidic sensor based on side-hole fiber with two long-period fiber gratings

We propose and demonstrate a dual-channel microfluidic sensor based on a side-hole fiber(SHF)with two longperiod 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.

Laser-induced rotary micromotor with high energy conversion efficiency

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 only10-15–10-12.In this paper,we propose and demonstrate a laser-induced rotary micromotor operated byΔα-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.TheΔα-type photophoretic force introduced by the conicalshaped 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.