Long-period fiber grating - Wikipedia
like to especially thank Predrag Mikulic for long-period fiber gratings fabrication for .. Objective Simulate the spectral properties of the LPFG place in the Its complexity and lack of detailed dates requires that certain. A long-period fiber grating couples light from a guided mode into forward propagating cladding modes where it is lost due to absorption and scattering. Publication Date (Web): June 1, Copyright . Smart design of a long- period fiber grating refractive index sensor based on dual-peak resonance near the.
The coupling from the guided mode to cladding modes is wavelength dependent so we can obtain a spectrally selective loss.
It is an optical fiber structure with the properties periodically varying along the fiber, such that the conditions for the interaction of several copropagating modes are satisfied. The period of such a structure is of the order of a fraction of a millimeter.
In contrast to the fiber Bragg gratingsLPFGs couple copropagating modes with close propagation constants; therefore, the period of such a grating can considerably exceed the wavelength of radiation propagating in the fiber.
Simulation method for analyzing mechanical long-period fiber gratings under high
Since LPFGs couple copropagating modes, their resonances can only be observed in transmission spectra. The transmission spectrum has dips at the wavelengths corresponding to resonances with various cladding modes in a single-mode fiber.
Depending on the symmetry of the perturbation that is used to write the LPFG, modes of different symmetries may be coupled. For instance, cylindrically symmetric gratings couple symmetric LP0m modes of the fiber.
Microbend gratingswhich are antisymmetric with respect to the fiber axis, create a resonance between the core mode and the asymmetric LP1m modes of the core and the cladding.
Long period grating has a wide variety of applications, including band-rejection filters, gain flattening filter and sensors.
Journal of Lightwave Technology
Related to this, it has to be underlined the fact that the amplitude of the spatial periodic variation of the refractive index inscribed in the core is smaller than nco—ncl [ 11 — 15 ]. Consequently, the spectral characteristics that can be observed in fiber reflection FBG and transmission LPG gratings will be described [ 13 — 19 ].
- Long-period fiber grating
- Numerical Simulation Methods Applied at Fiber Grating Sensors Design
- Fiber Bragg grating
For an improved design of experimental setups dedicated to the above-mentioned applications, it is obvious that, for both FBG and LPG, the principles for understanding and tools for designing fiber gratings are emphasized [ 11 — 20 ]. The emphasized understanding principles and designing tools are applicable for the wide variety of optical properties that are possible in fiber gratings [ 19 — 28 ].
There are given examples related to the large number of fiber grating subtypes of both FBG and LPG, considering uniform, apodized, chirped, discrete phase-shifted and superstructure gratings; symmetric and tilted gratings; and cladding-mode and radiation-mode coupling gratings [ 20 — 33 ]. Most commonly, the LPG is created by altering the core in a periodic manner, but another class of manufacturing methods physically deforms the fiber to create the required optical modulation [ 34 — 40 ].
Fiber Bragg grating - Wikipedia
These include the following: Consequently, the basics of simulation models are provided. Coupled-mode theory and the transfer matrix methods are the two techniques used for the simulation of FBG and LPG [ 1314172022 — 28 ].GIRLFRIEND SIMULATOR. -- Kanojo VR
Thus, the physical mechanism of the grating electric field interaction is given and aims to provide the reader with insight into the operation principles of FBG and LPG. The gratings are inscribed into the core of a step index optic fiber; consequently, the step index optic fiber case is analyzed.
Optical fiber mainly consists of a core, cladding and a protective layer called the primary plastic buffer coating.
The optical fiber acts as a waveguide for optical frequencies and is normally cylindrical in shape.