Broadening Adjustable Range on Post-Fabrication Resonance Wavelength Trimming of Long-Period Fiber Gratings and the Mechanisms of Resonance Wavelength Shifts

Transfer-matrix method based on a discrete coupling model for analyzing uniform and nonuniform codirectional fiber grating couplers

“…During the LPFG fabrication, the spectral transmission was monitored. The fiber was heated almost symmetrically by arc discharge and cooled rapidly in the air, and the coupling took place between the circularly symmetric core mode LP 01 and cladding modes LP 0m at the discharge points [6]. The coupling quantity and the propagation constants of the core and cladding modes are necessary to calculate the transmission spectra.…”

“…The accurate propagation constants of the core and cladding modes, β co and β cl , are essential for calculating transmission spectra of the codirectional grating couplers over a wide wavelength range. Effective indexes of the core and cladding modes of the SMF-28e fiber were calculated by using the equivalent staircase index profile with three layers of core, cladding, and air [6]. We applied the scalar approximation to calculate the effective indexes of the LP 01 core mode (n 01 ) and LP 0m cladding modes (n 0m ) in the fiber with three layers.…”

“…LPFGs are traditionally fabricated by using UV laser writing on a hydrogen-loaded fiber. Meanwhile, a point-by-point arc discharge technique is widely investigated, and it was shown that the advantages are the simple and flexible fabrication process, high temperature stability, availability of conventional silica fibers and pure silica photonic crystal fibers [1][2][3][4], and postfabrication resonance wavelength trimming [5,6].…”

Fabrication of long-period fiber gratings using low-pressure mercury lamp: Shortening of exposure time

“…Another method is periodic heating of a fiber. A focused CO 2 -laser beam [16][17][18][19] and an electric discharge 16,20,21) have been used for heating. Periodic exposure with a frequency-tripled Nd 3+ :YAG laser (355 nm), 22) femtosecond optical pulses, 23) and a focused ion beam 24) were also studied.…”