In this paper, a cholesterol biosensor is developed using a single-mode fiber (SMF) and a hollow core fiber (HCF) to detect and measure the cholesterol concentration in the human body. The ...sensitivity of an SMF-HCF structure (sensor probe) has been enhanced by the localized surface plasmon resonance (LSPR) technique using the gold nanoparticles (AuNPs) of 11± 0.5 nm particle size. Furthermore, sensor probe was functionalized with cholesterol oxidase (ChOx) enzyme to increase the selectivity of biosensor. The synthesis of AuNPs is confirmed by a UV-visible spectrophotometer, transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDS). Furthermore, the coating of AuNPs over an optical fiber is verified by scanning electron microscope (SEM). The linearity range and detection limit of the proposed sensor are 50 nM-<inline-formula> <tex-math notation="LaTeX">1~\mu \text{M} </tex-math></inline-formula> and 25.5 nM, respectively. The selectivity of biosensor has been determined with the 10-mM concentration of different solutions of cholesterol, glucose, urea, ascorbic acid, L-cysteine, and galactose that are generally present in serum.
This paper presents analytical results on longitudinal power profile estimation (PPE) methods, which visualize signal power evolution in optical fibers at a coherent receiver. The PPE can be ...formulated as an inverse problem of the nonlinear Schrödinger equation, where the nonlinear coefficient (and thus signal power) is reconstructed from boundary conditions, i.e., transmitted and received signals. Two types of PPE methods are reviewed and analyzed, including correlation-based methods (CMs) and minimum-mean-square-error-based methods (MMSEs). The analytical expressions for their output power profiles and spatial resolution are provided, and thus the theoretical performance limits of the two PPE methods and their differences are clarified. The derived equations indicate that the estimated power profiles of CMs can be understood as the convolution of a true power profile and a smoothing function. Consequently, the spatial resolution and measurement accuracy of CMs are limited, even under noiseless and distortionless conditions. Closed-form formulas for the spatial resolution of CMs are shown to be inversely proportional to the product of a chromatic dispersion coefficient and the square of signal bandwidth. With MMSEs, such a convolution effect is canceled out and the estimated power profiles approach a true power profile under a fine spatial step size.
We will present our recent work on the reliability of specialty optical fibers designed for use in silicon photonics, subjected to reflow soldering process conditions. Coating thermal stability, ...fiber mechanical properties, and induced optical loss after reflow soldering will be discussed. Performances of post-reflow fibers under temperature cycling and damp heat aging environmental tests will also be discussed.
As a new approach to realizing high-precision time synchronization between remote time scales, quantum two-way time transfer via laboratory fiber link has shown significant enhancement of the ...transfer stability to several tens of femtoseconds. To verify its great potential in practical systems, the field test in long-haul installed fiber optic infrastructure is required to be demonstrated. In this article, we implement the two-way quantum time transfer over a 103 km urban fiber link. A time transfer stability of 3.67 ps at 10 s and 0.28 ps at 40 000 s has been achieved, despite the large attenuation of 38 dB leading to fewer than 40 correlated events per second. This achievement marks the first successful step of quantum two-way time transfer in the task of high-precision long-distance field transfer systems.
The power scaling of single mode fiber lasers and amplifiers, due to the wide area of applications, has been the subject of great interest for many years. Increasing the mode area seems to be the ...obvious way to scale up the output power level from the single emitter if you consider well-known limitations like nonlinear effects, material damage threshold or thermal lensing. The nanostructurization of the fiber core is a method to control precisely optical properties of the active fiber. This method allows to design and develop the fiber with the core of any arbitrary defined refractive index distribution, with precision not available with other known fiber technology. The nanostructurization also open up an opportunity to incorporate simultaneously various active and non-active glasses into the fiber core. Those advantages can be used to fabricate the new class of fibers for laser applications. Here we show ytterbium doped phosphate single-mode fiber with nanostructured core, which is the first proof-of-concept of active fiber with entirely nanostructured core area.
Fiber optic surface plasmon resonance (SPR) sensors have achieved a large number of solutions for sensing physical quantities such as refractive index, micro displacement, curvature, strain, etc. ...However, there are few schemes for sensing torsional physical quantities. This article proposes an optical fiber SPR torsion sensor based on a threaded structure. A threaded structure that is prone to deformation during torsion is etched on the optical fiber. After the threaded area, an SPR sensing area is created. Clockwise rotation causes compression deformation in the threaded area, while counterclockwise rotation causes tensile deformation in the threaded area, resulting in a change in the optical transmission mode of the threaded area, changing the SPR incidence angle, causing the corresponding SPR resonance valley to move. Torsion sensing is achieved through the shift of the SPR resonance wavelength, and the torsion direction is determined by the shift direction of wavelength. The experiment indicates that the sensing probe has a clockwise twist sensitivity of 0.9088nm/(rad/m) and a counterclockwise twist sensitivity of -0.8291nm/(rad/m) within the detection range of -47.10rad/nm to 47.10rad/nm, providing a new scheme for directional detection of torsional physical quantities.
The combination of multi-band optical transmission and ITU-T G.654 loss-minimized large-effective-area fibers enables superior network performance in the low-loss C+L wavelength bands. As the maximum ...cut-off wavelength of the G.654 fiber is increased to 1530 nm, from 1260 nm in the commonly used G.652 fiber, the multi-path interference (MPI) resulting from the interplay between the fundamental LP01 mode and the high-order LP11 mode needs to be considered when expanding the multi-band transmission window to cover the S+E+O bands. In this paper, we study optical layer impairments such as the LP01-LP11 mode coupling induced MPI in G.654 fiber, the negative impact of the stimulated Raman scattering (SRS) on the use of optical supervisory channel (OSC) and optical time domain reflectometer (OTDR) in all fiber types, and the four-wave-mixing (FWM) issue in the O-band transmission over G.652 fiber, and discuss the corresponding mitigation techniques. Extensive measurements of G.654.E fibers are made to evaluate the MPI. For impact of MPI, we include it, along with the nonlinear interference, in the generalized Gaussian noise model to accurately assess the link performance, and mitigation strategies are discussed. Additional considerations of diverse optical link conditions on amplification schemes, link distances, and cost constraints are made for provisioning C+L+S+E+O multi-band optical networks with the combined use of both G.652 and G.654 fibers, aiming for the optimal utilization of the multi-band transmission in future ultrahigh-capacity optical networks for a wide variety of applications.
High Power Fiber Lasers: A Review Zervas, Michalis N.; Codemard, Christophe A.
IEEE journal of selected topics in quantum electronics,
09/2014, Letnik:
20, Številka:
5
Journal Article
Recenzirano
In this paper, we summarize the fundamental properties and review the latest developments in high power fiber lasers. The review is focused primarily on the most common fiber laser configurations and ...the associated cladding pumping issues. Special attention is placed on pump combination techniques and the parameters that affect the brightness enhancement observed in single-mode and multimode high power fiber lasers. The review includes the major limitations imposed by fiber nonlinearities and other parasitic effects, such as optical damage, transverse modal instabilities and photodarkening. Finally, the paper summarizes the power evolution in continuous-wave and pulsed ytterbium-doped fiber lasers and their impact on industrial applications.
A weakly coupled multi-core fiber with the standard 125-μm cladding diameter has shown promise as a next-generation large-capacity transmission medium for long-haul networks that can provide multiple ...optical paths while maintaining the existing cable structure. In this article, we numerically and experimentally demonstrate a standard cladding 4-core fiber (4CF) with a superior transmission performance in terms of figure-of-merit (FOM), which is defined as the relative spectral efficiency to a conventional G.654 fiber, by simultaneously optimizing the design of its effective area and loss and crosstalk characteristics for submarine transmission. By considering a counter-propagation configuration among neighboring cores, we can obtain larger effective area of the optimized 4CF design because of the relaxed tradeoff relationship with the crosstalk. Specifically, we report a 10,140-km transmission with the spectral efficiency of 7.52 bit/s/Hz using a counter-propagation configuration, which indicates we can exceed a 1 Pbit/s cable capacity when considering a conventional 17-mm-diameter submarine cable. We also investigate the applicability of the standard cladding 4CF to wide-band transmission in the C+L band to see if it is appropriate for a long-distance terrestrial system. Our findings show that our design of 4CF to maximize the FOM for co- and counter-propagation between cores enables us to obtain a higher FOM in not only the C band but also the C+L band.
We present a symmetric physical layer based secret key generation scheme for Point-to-Point Optical Link (PPOL) communication by exploiting Polarization Mode Dispersion (PMD) as a random and ...inimitable channel characteristic. The randomness and security strength of generated cryptographic keys based on PMD is significantly high. In this paper, we present that random modulation of a probe signal caused by PMD in a high-speed data communication network (40 Gb/s and 60 Gb/s) is reciprocal with average Pearson correlation coefficient of 0.862, despite the presence of optical nonlinearities, dispersion, and noise in the system. 128-bit symmetric cryptographic key has been successfully generated using the proposed scheme. Moreover, PMD-based encryption keys passed the National Institute of Standards and Technology (NIST) tests. We have shown through simulations with a 50 km link that, with optimal key generation settings, symmetric keys can be generated with high randomness (high P-values for NIST randomness tests) and with sufficient generation rates (>50%). Furthermore, we considered an attack model of a non-invasive adversary intercepting at 10 km into the link and found that the generated keys have high average key bit mismatch rates (>40%).