Dear Colleagues,

Nowadays, transmission of laser-excited optical signals over large-core silica optical fibers is widely used in various applications. This technique, combined with special launching conditions, provides a few-mode regime. Here, laser-excited optical emission is transferred over large-core optical fiber using a limited number of guided modes. Meanwhile, under the multimode regime, the transmitted optical signal contains almost all guided modes, satisfying cut-off conditions. Since the IEEE 802.3z standard was ratified in 1998, laser-based optical signal transmission over MMFs has been widely used for short-range multi-Gigabit solutions. It remains in demand for on-board and industrial network applications, requiring bit rates of 1 Gb/s or more, whereas silica MMFs with extremely enlarged core diameters up to 100 mm, as well as silica–polymer or polymer-polymer MMFs, are utilized.

Today, MMFs—as well as few-mode optical fibers (FMFs)—are also considered an alternative solution for new-generation transport networks, providing extra-high bit rates of hundreds Tb/s and more. Nonlinear effects, occurring in standard silica single-mode optical fibers during propagation of optical signals grouped by DWDM systems, are the main issue, and a passage to enhancing of fiber-effective area through core diameter enlargement in combination with MIMO technique is one of the approaches for decreasing or even almost suppression of optical fiber own nonlinearity for telecommunication system signals.

Presently, mode division multiplexing (MDM) is one of the new top trends in optical networking, which applies spatial mode or optical angular moments (OAMs) multiplexing. Moreover, MMFs as well FMFs have many applications outside telecommunications, in areas such as fiber-optic sensors, medicine; fiber-optic lasers/laser delivery systems; light sources for illumination; endoscopes; remote viewing; and others. A few-mode regime adds another new dimension to the space of parameters: it is associated with guided modes of particular order, of which a limited number (from two to a few dozen) transfer the greater part of the optical signal power over tested optical fiber.

Therefore, new multi- and few-mode effects, as well as utilization and customization of known multi- and few-mode regimes for specified applications in telecommunications, sensorics, medicine, fiber-optic lasers/laser-delivery systems, light sources for illumination, endoscopes, remote viewing, and other topics are the focus of the presented Special Issue. This Special Issue covers a broad scope of research in the area of multi- and few-mode effects in optical fibers, and solicits contributions including, but not limited to:

• MMFs and FMFs for telecommunications;
• MDM / SDM;
• MIMO technique for optical networks with MMFs and FMFs;
• laser optimized multimode optical fibers;
• FMFs;
• laser-based multi-Gigabit data transmission over large core optical fibers;
• fiber optic sensors based on a few-mode effects;
• extremely enlarged core optical fibers;
• MMFs and FMFs in medicine;
• MMFs and FMFs in lasers/laser delivery systems;
• image transmission over MMFs and FMFs;
• chiral MMFs and FMFs;
• Microstructured and photonic crystal MMFs and FMFs.

Prof. Dr. Anton Bourdine
Prof. Dr. Manish Tiwari
Dr. Airat Zh. Sakhabutdinov
Guest Editors

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