Optical fibers are typically used in telecommunications services for data transmission, where the use of fiber tags is essential to distinguish between the different transmission fibers or channels and thus ensure the working functionality of the communication system. Traditional physical entity marking methods for fiber labeling are bulky, easily confused, and, most importantly, the label information can be accessed easily by all potential users. This work proposes an encrypted optical fiber tag based on an encoded fiber Bragg grating (FBG) array that is fabricated using a point-by-point femtosecond laser pulse chain inscription method. Gratings with different resonant wavelengths and reflectivities are realized by adjusting the grating period and the refractive index modulations. It is demonstrated that a binary data sequence carried by a fiber tag can be inscribed into the fiber core in the form of an FBG array, and the tag data can be encrypted through appropriate design of the spatial distributions of the FBGs with various reflection wavelengths and reflectivities. The proposed fiber tag technology can be used for applications in port identification, encrypted data storage, and transmission in fiber networks.

Ultrasensitive nanomechanical instruments, e.g. atomic force microscopy (AFM), can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes. However, these instruments are limited because of their size and complex feedback system. In this study, we demonstrate a miniature fiber optical nanomechanical probe (FONP) that can be used to detect the mechanical properties of single cells and in vivo tissue measurements. A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography. To realize stiffness matching of the FONP and sample, a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics. As a proof-of concept, three FONPs with spring constants varying from 0.421 N m⁻¹ to 52.6 N m⁻¹ by more than two orders of magnitude were prepared. The highest microforce sensitivity was 54.5 nm μN⁻¹ and the detection limit was 2.1 nN. The Young’s modulus of heterogeneous soft materials, such as polydimethylsiloxane, muscle tissue of living mice, onion cells, and MCF-7 cells, were successfully measured, which validating the broad applicability of this method. Our strategy provides a universal protocol for directly programming fiber-optic AFMs. Moreover, this method has no special requirements for the size and shape of living biological samples, which is infeasible when using commercial AFMs. FONP has made substantial progress in realizing basic biological discoveries, which may create new biomedical applications that cannot be realized by current AFMs.