Mid-infrared photoacoustic brain imaging enabled by cascaded gas-filled hollow-core fiber lasers.

Significance: Extending the photoacoustic microscopy (PAM) into the mid-infrared (MIR) molecular fingerprint region constitutes a promising route toward label-free imaging of biological molecular structures. Realizing this objective requires a high-energy nanosecond MIR laser source. However, existing MIR laser technologies are limited to either low pulse energy or free-space structure that is sensitive to environmental conditions.

Laser: A two-domain photon-phonon laser.

The laser is one of the greatest inventions in history. Because of its ubiquitous applications and profound societal impact, the concept of the laser has been extended to other physical domains including phonon lasers and atom lasers. Quite often, a laser in one physical domain is pumped by energy in another.

Unsupervised full-color cellular image reconstruction through disordered optical fiber.

Recent years have witnessed the tremendous development of fusing fiber-optic imaging with supervised deep learning to enable high-quality imaging of hard-to-reach areas. Nevertheless, the supervised deep learning method imposes strict constraints on fiber-optic imaging systems, where the input objects and the fiber outputs have to be collected in pairs. To unleash the full potential of fiber-optic imaging, unsupervised image reconstruction is in demand.

Adaptive inverse mapping: a model-free semi-supervised learning approach towards robust imaging through dynamic scattering media.

Imaging through scattering media is a useful and yet demanding task since it involves solving for an inverse mapping from speckle images to object images. It becomes even more challenging when the scattering medium undergoes dynamic changes. Various approaches have been proposed in recent years.

High-performance vector bending and orientation distinguishing curvature sensor based on asymmetric coupled multi-core fibre.

Fibre optic technology is rapidly evolving, driven mainly by telecommunication and sensing applications. Excellent reliability of the manufacturing processes and low cost have drawn ever increasing attention to fibre-based sensors, e.g.

Erratum: Author Correction: Complete polarization control in multimode fibers with polarization and mode coupling.

[This corrects the article DOI: 10.1038/s41377-018-0047-4.].

A path to high-quality imaging through disordered optical fibers: a review.

In this paper, we review recent progress in disordered optical fiber featuring transverse Anderson localization and its applications for imaging. Anderson localizing optical fiber has a transversely random but longitudinally uniform refractive index profile. The strong scattering from the transversely disordered refractive index profiles generates thousands of guiding modes that are spatially isolated and mainly demonstrate single-mode properties.

Complete polarization control in multimode fibers with polarization and mode coupling.

Multimode optical fibers have seen increasing applications in communication, imaging, high-power lasers, and amplifiers. However, inherent imperfections and environmental perturbations cause random polarization and mode mixing, causing the output polarization states to be different from the input polarization states. This difference poses a serious issue for employing polarization-sensitive techniques to control light-matter interactions or nonlinear optical processes at the distal end of a fiber probe.

Photonic lantern broadband orbital angular momentum mode multiplexer.

Optical vortex beams that carry orbital angular momentum (OAM), also known as OAM modes, have attracted considerable interest in recent years as they can comprise an additional degree of freedom for a variety of advanced classical and quantum optical applications. While canonical methods of OAM mode generation are effective, a method that can simultaneously generate and multiplex OAM modes with low loss and over broad spectral range is still in great demand. Here, via novel design of an optical fiber device referred to as a photonic lantern, where the radial mode index ("m") is neglected, for the first time we demonstrate the simultaneous generation and multiplexing of OAM modes with low loss and over the broadest spectral range to date (550 nm).

Few-mode fibre-optic microwave photonic links.

The fibre-optic microwave photonic link has become one of the basic building blocks for microwave photonics. Increasing the optical power at the receiver is the best way to improve all link performance metrics including gain, noise figure and dynamic range. Even though lasers can produce and photodetectors can receive optical powers on the order of a Watt or more, the power-handling capability of optical fibres is orders-of-magnitude lower.

Image Transport Through Meter-Long Randomly Disordered Silica-Air Optical Fiber.

We present a randomly disordered silica-air optical fiber featuring a 28.5% air filling fraction in the structured region, and low attenuation below 1 dB per meter at visible wavelengths. The quality of images transported through this fiber is shown to be comparable to, or even better than, that of images sent through commercial multicore imaging fiber.

Time-division-multiplexed few-mode passive optical network.

We demonstrate the first few-mode-fiber based passive optical network, effectively utilizing mode multiplexing to eliminate combining loss for upstream traffic. Error-free performance has been achieved for 20-km low-crosstalk 3-mode transmission in a commercial GPON system carrying live Ethernet traffic. The alternative approach of low modal group delay is also analyzed with simulation results over 10 modes.