A Sagnac interferometer has been a powerful tool for gyroscope, spectroscopy, and navigation based on the Sagnac effects between counterpropagating twin fields in a closed loop, whose difference phase is caused by Einstein’s special relativity. Here, a nonclassical version of a Sagnac interferometer is presented using completely different physics of coherence de Broglie waves (CBW) in a cavity, where CBW is a nonclassical feature overcoming the standard quantum limit governed by classical physics.

Brillouin-based fiber-optic sensing has been regarded as a powerful distributed measurement tool for monitoring the conditions of modern large civil and geotechnical structures, since it provides continuous environmental information (e.g., temperature and strain) along the whole fiber used for sensing applications. In the past few decades, great research efforts were devoted to improve its performance in terms of measurement range, spatial resolution, measurement speed, sensitivity, and cost-effectiveness, of which the slope-assisted measurement scheme, achieved by exploiting the linear slope of the Brillouin gain spectrum (BGS), have paved the way for dynamic distributed fiber-optic sensing. In this article, slope-assisted Brillouin-based distributed fiber-optic sensing techniques demonstrated in the past few years will be reviewed, including the slope-assisted Brillouin optical time-domain analysis/reflectometry (SA-BOTDA/SA-BOTDR), the slope-assisted Brillouin dynamic grating (BDG) sensor, and the slope-assisted Brillouin optical correlation domain analysis/reflectometry (SA-BOCDA/SA-BOCDR). Avenues for future research and development of slope-assisted Brillouin-based fiber-optic sensors are also prospected.

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.

A deep learning model was built to optimize the phase flicker performance for given pulse width modulation (PWM) driving patterns of a liquid crystal on silicon (LCOS) device. 10-bit phase modulation was physically realized with a phase flicker of 0.055% over 1024 addressed phase levels in respect to the total modulation range of and a separation probability of 62.63% for the phase to stay within its level without overlapping with the adjacent ones. The spatial information bandwidth of the full high-definition (HD) LCOS device at 100 Hz was improved by 25%, from ~1.6 Gb/sec to ~2 Gb/sec.