Fabrication of Optical Fiber and Fiber Amplifiers: From Design to Applications

Dear Colleagues,

The earliest development stage of optical fibers benefited from peoples’ pursuit of high-capacity communication. Apart from light transmission, optical fibers can also be utilized in sensing, filtering, amplification, and lasering. Different applications have incubated innovation in materials, structures, and fabrication methods of optical fibers. In terms of materials, substrates (such as silica and soft silica), polymers, and dopants (such as erbium, ytterbium, fluorine, and bismuth) are utilized to manufacture optical fibers with different functions. As for the structures, in addition to the traditional double-layered core-cladding fiber structure, multi-layered, multi-core, and micro-structured optical fibers are also developed. The fabrication of optical fibers involves methods such as vapor deposition methods, microtapering, and even 3D printing. Moreover, a combination of different materials, structures, and fabrication methods has led to the innovation and improvement of various functional fiber optic devices, such as FBGs and fiber interferometers. More materials, structures, and fabrication methods can be developed and improved to meet the new requirements of different applications.

Fiber amplifiers comprise an important branch of fiber optic devices. There are two main categories of fiber amplifiers: rare-earth-doped fiber amplifiers (such as erbium-doped fiber amplifiers (EDFAs)) and nonlinear fiber amplifiers (such as fiber Raman amplifiers and fiber Brillouin amplifiers). EDFAs are widely used in wavelength division multiplexing (WDM) and dense wavelength division multiplexing (DWDM) systems. Larger capacity communication systems pose new demands for fiber amplifiers. For example, mode division multiplexing (MDM) and space division multiplexing (SDM) systems require few high-performance mode EDFAs and multi-core EDFAs. EDFAs mainly operate in the C-band and L-band. In order to expand the wavelength band and further improve the communication capacity, other rare-earth-doped fiber amplifiers (such as bismuth-doped fiber amplifiers), fiber Raman amplifiers, and fiber Brillouin amplifiers also need to be studied and improved.

This Special Issue on “Fabrication of Optical Fiber and Fiber Amplifier: From Design to Applications” will welcome basic, methodological, and cutting-edge research contributions, as regular and review papers that focus on:

• The development and improvement of materials, and design and fabrication methods for optical fibers;
• Specialty optical fibers, such as micro-structured optical fibers and polymer fibers;
• Special erbium-doped fiber amplifiers (EDFAs), such as few-mode EDFAs and multicore EDFAs;
• Other rare-earth-doped fiber amplifiers, such as bismuth-doped fiber amplifiers;
• Nonlinear fiber amplifiers, including fiber Raman amplifiers and fiber Brillouin amplifiers;
• Applications based on optical fibers and fiber amplifiers, such as optical fiber sensors and optical fiber lasers.

Dr. Shiying Xiao
Dr. Beilei Wu
Dr. Yudong Lian
Guest Editors

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• optical fibers
• specialty optical fibers
• optical fiber amplifiers
• EDFAs
• rare-earth-doped fiber amplifiers
• fiber Raman amplifiers
• fiber Brillouin amplifiers
• optical fiber sensors
• optical fiber lasers

Title: Enhanced DWT-NLM for multimode fiber optic vibration signal
Authors: Zixuan Peng; Kaimin Yu; Yuanfang Zhang; Peibin Zhu; Wen Chen; Jianzhong Hao
Affiliation: School of Ocean Information Engineering, Jimei University
Abstract: Real-time monitoring of heartbeat signals using multimode fiber optic microvibration sensing technology is crucial for diagnosing cardiovascular diseases, but the heartbeat signals are very weak and susceptible to noise interference, leading to inaccurate diagnostic results. In this paper, a combined enhanced discrete wavelet transform (DWT) and nonlocal mean estimation (NLM) denoising method is proposed to remove noise from heartbeat signals, which adaptively determines the filtering parameters of the DWT -NLM composite method using objective noise reduction quality assessment metrics. By denoising different ECG signals from multiple databases with the addition of additive Gaussian white noise (AGW) with different signal-to-noise ratios (SNR). The noise reduction results are compared with those of NLM, enhanced DWT and conventional DWT combined with NLM method. The results show that the output SNR of the proposed method is significantly higher than the other methods compared in the range of -5 to 25 dB input SNR. Further, the proposed method is employed for noise reduction of heartbeat signals measured by fiber optic microvibration sensing. It is worth mentioning that the proposed method does not need to obtain the exact noise level, but only the adaptive filtering parameters based on the autocorrelation nature of the denoised signal. This work greatly improves the signal quality of the multimode fiber microvibration sensing system and helps to improve the diagnostic accuracy.