scholarly journals Control of Excitation of Cladding Modes by Tapering an Insertion of Special Fiber

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2498
Author(s):  
Diomid D. Bakurov ◽  
Oleg V. Ivanov
Keyword(s):  
Field Distribution ◽  
Refractive Indices ◽  
Coupling Coefficients ◽  
Core Mode ◽  
Transmission Characteristics ◽  
Tapered Fiber ◽  
Fiber Core ◽  
The Core

A method for controlling the excitation of cladding modes by tapering special fiber insertions made of SM450 and coreless fibers is proposed. The coupling coefficients between the core mode and the cladding modes of the tapered fiber insertion are calculated. For the calculation, changes in the effective refractive indices and phases of the fiber core and in the cladding modes upon tapering are found. The field distribution of the core mode of the standard fiber transmitted through fiber insertion is obtained. The transmission characteristics of insertions of SM450 and coreless fibers during tapering are simulated and compared with the experiment. The possibility of controlling the transmission and excitation of various cladding modes is confirmed experimentally.

scholarly journals High-Sensitivity Refractive Index Sensor Based on a Cascaded Core-Offset and Macrobending Single-Mode Fiber Interferometer

2021 ◽  
Vol 7 ◽  
Author(s):  
Chuanxin Teng ◽  
Yongjie Zhu ◽  
Fangda Yu ◽  
Shijie Deng ◽  
Libo Yuan ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Sensitivity ◽  
Single Mode ◽  
Spectral Shift ◽  
Single Mode Fiber ◽  
Refractive Index Sensor ◽  
Core Mode ◽  
Fiber Core ◽  
The Core ◽  
Modal Interference

A high-sensitivity Mach–Zehnder interferometer (MZI) based on the cascaded core-offset and macrobending fiber structure is proposed for refractive index (RI) measurement. The core-offset structure makes the fiber core mode couple to the cladding modes, and some of them recouple back to the fiber core at the macrobending structure forming a model interference effect. The liquid RI can be measured by monitoring the spectral shift of the modal interference. The RI sensing performances for the interferometers with different macrobending radii and core offsets are investigated experimentally. Experimental results show that when the core offset is 2 μm and the macrobending radius is 5.5 mm, the sensitivity can reach 699.95 nm/RIU for the RI of 1.43. The temperature dependence for the proposed sensor is also tested, and a temperature sensitivity of 0.112 nm/°C is obtained.

Study of Birefringence and Mode Field for Hollow-Core Photonic Bandgap Fiber

2014 ◽  
Vol 609-610 ◽  
pp. 324-329
Author(s):  
Li Shuang Feng ◽  
Wen Shuai Song ◽  
Xiao Yuan Ren
Keyword(s):  
Field Distribution ◽  
Photonic Bandgap ◽  
Surface Mode ◽  
Hollow Core ◽  
The Finite Element Method ◽  
Core Mode ◽  
Photonic Bandgap Fiber ◽  
Mode Field ◽  
Air Core ◽  
Polarization Maintaining

Since the Appearance of Hollow-Core Photonic Bandgap Fiber (HC-PBF), it was Widely Concerned for its Excellent Characteristics. in Order to Study the Characteristics of the HC-PBF that can be Used in Resonator Fiber Optic Gyros (R-Fogs), the Model Structure of a Polarization-Maintaining HC-PBF was Built and its Performance was Simulated by Using the Finite Element Method (FEM). its Mode Field Distribution and Birefringence Characteristics were Obtained. the Influences of the Air Core and Cladding Structures on the Mode Field Distribution and Birefringence were Simulated and Analyzed Further. the Result Showed that there are both Core Mode and Surface Mode in the Structure we Built. by Adding Scattering Points into the Fiber Core, the Surface Mode can be Significantly Suppressed. by Matching the Size of Core and Air Holes around the Core, a Birefringence up to 8*10-4 were Obtained.

Parallel analysis of thermal field in a layered DC cable

2014 ◽  
Vol 24 (3) ◽  
pp. 613-626
Author(s):  
Jerzy Golebiowski ◽  
Robert Piotr Bycul
Keyword(s):  
Steady State ◽  
Field Distribution ◽  
Time Constant ◽  
Thermal Field ◽  
Thermal Time ◽  
Content Type ◽  
The Core ◽  
Thermal Time Constant ◽  
Steady State Current

Purpose – The purpose of this paper is to prepare procedures for determination of characteristics and parameters of DC cables on the basis of transient and steady thermal field distribution in their cross-sections. Design/methodology/approach – Steady-state current rating was computed iteratively, with the use of steady thermal field distribution in the cable. The iterative process was regulated with respect to this field by changes of the mean surface temperature of the sheath of the cable. It was also controlled with respect to the unknown current rating by deviations of the temperature of the core from the maximum sustained temperature of the insulation (material zone) adjacent to the core. Heating curves were determined (in arbitrarily selected points of the cross-section of the cable) by a parallel algorithm described thoroughly in the first part of the paper. The algorithm was used for computing of transient thermal field distribution throughout the whole cross-section. Thermal time constant distributions were determined by the trapezium rule, where the upper integration limit of respective thermal field distributions was being changed. Findings – Using the methods prepared the following characteristics/parameters of the cable were determined: steady-state current rating, spatial-time heating curves, mean thermal time constant distribution. The results were verified and turned to be in conformance with those of the IEC 287 Standard and a commercial software – Nisa v. 16. Speedup and efficiency of the parallel computations were calculated. It was concluded that the parallel computations took less time than the sequential ones. Research limitations/implications – The specialized algorithms and software are dedicated to cylindrical DC cables. Practical implications – The knowledge of the determined characteristics and parameters contributes to optimal exploitation of a DC cable during its use. Originality/value – The algorithms of determination of the steady-state current rating and thermal time constant are original. The software described in the appendix has also been made by the authors.

scholarly journals Effect of Near-field Distribution on Transmission Characteristics of Fiber-fed Fabry–Perot Etalons

2021 ◽  
Vol 161 (6) ◽  
pp. 258
Author(s):  
Jun Hao ◽  
Liang Tang ◽  
Huiqi Ye ◽  
Zhibo Hao ◽  
Jian Han ◽  
...  
Keyword(s):  
Field Distribution ◽  
Near Field ◽  
Transmission Characteristics ◽  
Fabry Perot

Fiber core mode leakage induced by refractive index variation in high-power fiber laser

2017 ◽  
Vol 26 (3) ◽  
pp. 034205 ◽  
Author(s):  
Ping Yan ◽  
Xuejiao Wang ◽  
Yusheng Huang ◽  
Chen Fu ◽  
Junyi Sun ◽  
...  
Keyword(s):  
Refractive Index ◽  
Fiber Laser ◽  
High Power ◽  
Core Mode ◽  
Refractive Index Variation ◽  
Fiber Core ◽  
Index Variation

Ytterbium doped phosphate glass photonic crystal fiber laser

2009 ◽  
Vol 17 (3) ◽  
Author(s):  
M. Franczyk ◽  
R. Stępień ◽  
D. Pysz ◽  
I. Kujawa ◽  
R. Buczyński ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Phosphate Glass ◽  
Single Mode ◽  
Refractive Indices ◽  
Photonic Crystal Fibre ◽  
Single Mode Operation ◽  
Crystal Fiber ◽  
The Core ◽  
The Difference ◽  
Doped Glass

AbstractWe demonstrate the 3% mol ytterbium doped phosphate glass air-clad photonic crystal fibre (PCF) laser of 43-cm length in single-mode operation. The fabrication and testing of the laser is introduced. The laser has the diameter of the core of 12 µm created in photonic microstructure and generates at wavelength of 1030 nm. Near 4-W output power and 14.6% slope efficiency against the launched pump power is demonstrated in preliminary characterization. The difference of refractive indices achieved in doped and undoped glass is Δn = 0.0004. We used the doped glass with the negative core-cladding Δn to assure the photonic crystal fibre way of single-mode propagation.

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