Thermally drawn multimaterial fibers have experienced rapid development in the past two decades owing to the high scalability, uniformity, and material and structure compatibility of the thermal drawing technique. This article reviews various multimaterial fibers based on different functional structures and their applications in disparate fields. We start from the functional structures achieved in optical fibers developed in the early stage of thermally drawn fibers. Subsequently, we introduce both typical functional structures and unique structures created in multimaterial fibers for varying applications. Next, we present the early attempts in breaking the axial symmetric structures of thermally drawn fibers for extended functionalities. Additionally, we summarize the current progress on creating surface structures on thermally drawn fibers. Finally, we provide an outlook for this trending topic towards wearable devices and smart textiles.

Recently, Rayleigh scattering-based distributed fiber sensors have been widely used for measurement of static and dynamic phenomena such as temperature change, dynamic strain, and sound waves. In this review paper, several sensing systems including traditional Rayleigh optical time domain reflectometry (OTDR), -OTDR, chirped pulse -OTDR, and optical frequency domain reflectometry (OFDR) are introduced for their working principles and recent progress with different instrumentations for various applications. Beyond the sensing technology and instrumentation, we also discuss new types of fiber sensors, such as ultraweak fiber Bragg gratings and random fiber gratings for distributed sensing and their interrogators. Ultimately, the limitations of Rayleigh-based distributed sensing systems are discussed.

Light-matter interactions have been explored for more than 40 years to achieve physical modulation of nanostructures or the manipulation of nanoparticle/biomolecule. Silicon photonics is a mature technology with standard fabrication techniques to fabricate micro- and nano-sized structures with a wide range of material properties (silicon oxides, silicon nitrides, p- and n-doping, etc.), high dielectric properties, high integration compatibility, and high biocompatibilities. Owing to these superior characteristics, silicon photonics is a promising approach to demonstrate optical force-based integrated devices and systems for practical applications. In this paper, we provide an overview of optical force in silicon nanophotonic and optomechanical systems and their latest technological development. First, we discuss various types of optical forces in light-matter interactions from particles or nanostructures. We then present particle manipulation in silicon nanophotonics and highlight its applications in biological and biomedical fields. Next, we discuss nanostructure mechanical modulation in silicon optomechanical devices, presenting their applications in photonic network, quantum physics, phonon manipulation, physical sensors, etc. Finally, we discuss the future perspective of optical force-based integrated silicon photonics.