Metamaterials are composed of periodic subwavelength metallic/dielectric structures that resonantly couple to the electric and magnetic fields of the incident electromagnetic waves, exhibiting unprecedented properties which are most typical within the context of the electromagnetic domain. However, the practical application of metamaterials is found challenging due to the high losses, strong dispersion associated with the resonant responses, and the difficulty in the fabrication of nanoscale 3D structures. The optical metasurface is termed as 2D metamaterials that inherent all of the properties of metamaterials and also provide a solution to the limitation of the conventional metamaterials. Over the past few years, metasurfaces; have been employed for the design and fabrication of optical elements and systems with abilities that surpass the performance of conventional diffractive optical elements. Metasurfaces can be fabricated using standard lithography and nanoimprinting methods, which is easier campared to the fabrication of the counterpart 3 days metamaterials. In this review article, the progress of the research on metasurfaces is illustrated. Concepts of anomalous reflection and refraction, applications of metasurfaces with the Pancharatanm-Berry Phase, and Huygens metasurface are discussed. The development of soft metasurface opens up a new dimension of application zone in conformal or wearable photonics. The progress of soft metasurface has also been discussed in this review. Meta-devices that are being developed with the principle of the shaping of wavefronts are elucidated in this review. Furthermore, it has been established that properties of novel optical metasurface can be modulated by the change in mechanical, electrical, or optical stimuli which leads to the development of dynamic metasurface. Research thrusts over the area of tunable metasurface has been reviewed in this article. Over the recent year, it has been found that optical fibers and metasurface are coagulated for the development of optical devices with the advantages of both domains. The metasurface with lab-on fiber-based devices is being discussed in this review paper. Finally, research trends, challenges, and future scope of the work are summarized in the conclusion part of the article.‬‬‬‬‬‬‬

A novel intrinsic fiber optic pressure sensor realized with a polarization-maintaining photonic crystal fiber (PM-PCF) based Sagnac interferometer is proposed and demonstrated experimentally. A large wavelength–pressure coefficient of $3.42\mathrm{nm}/\mathrm{MPa}$ was measured using a $58.4\mathrm{cm}$ long PM-PCF as the sensing element. Owing to the inherently low bending loss and thermal dependence of the PM-PCF, the proposed pressure sensor is very compact and exhibits low temperature sensitivity.

Phase-sensitive optical time-domain reflectometry (Φ-OTDR) has attracted numerous attention due to its superior performance in detecting the weak perturbations along the fiber. Relying on the ultra-sensitivity of light phase to the tiny deformation of optical fiber, Φ-OTDR has been treated as a powerful technique with a wide range of applications. It is fundamental to extract the phase of scattering light wave accurately and the methods include coherent detection, I/Q demodulation, 3 by 3 coupler, dual probe pulses, and so on. Meanwhile, researchers have also made great efforts to improve the performance of Φ-OTDR. The frequency response range, the measurement accuracy, the sensing distance, the spatial resolution, and the accuracy of event discrimination, all have been enhanced by various techniques. Furthermore, lots of researches on the applications in various kinds of fields have been carried out, where certain modifications and techniques have been developed. Therefore, Φ-OTDR remains as a booming technique in both researches and applications.