Tunable fiber laser based on the refractive index characteristic of MMI effects

Highly sensitive bending sensor based on multimode–multimode–coreoffset fiber structure

“…Besides, most of the sensors were applied to monitor the resonance wavelength. The sensitivity represented in the previous paper was about 274 nm/RIU in the RI range from 1.333 to 1.427 [18]. When the length of the NCF is as short as hundreds of microns, the transmission spectrum proximately exhibits a straight line monitored by the OSA.…”

Optical Sensing Using Fiber-Optic Multimode Interference Devices: A Review of Nonconventional Sensing Schemes

“…In other words, can be altered optically only for smaller values of , that is, for thin MMFs. Indeed, if the diameter of the MMF is reduced, two effects contribute to make the evanescent penetration deeper overall: If is reduced, the second term in Equation (10) becomes significant and, at the same time, the confinement factor decreases due to the smaller core, thus giving rise to longer evanescent tails [ 18 , 19 , 20 ]. Based on this, a typical approach to enhance the sensitivity to the surroundings relies on either tapering or etching down the MMF diameter to produce longer evanescent tails, as will become evident later.…”

Optical Property of Polarization-Maintaining Fiber Taper for Tunable Multi-Wavelength Fiber Laser Generation

“…Previously, tunable laser operation can be achieved by mode-selection using thin film filter, acousto-optic tunable filter in laser resonators [4], [5]. However, as to increase the compactness and reduce intracavity loss, fiber filters are used, such as fiber Bragg gratings (FBGs) [6], [7], high birefringence (HiBi) Sagnac interferometers [8], [9] and Mach-Zehnder interferometers (MZIs) [10], [11]. Wavelength tuning ability of the FBG is determined by its strain characteristics.…”

“…Laser stability of using the high birefringence (HiBi) Sagnac interferometers needs to be improved due to the dimension of the interference ring is relatively complex for integration. As for the MZI, the length of the two interference arms should to be precisely controlled [9]. Nonlinear effects in optical fibers could also be used for tunable laser mode-selection in fiber laser cavities, such as stimulated Brillouin scattering (SBS) [2], nonlinear polarization rotation (NPR) and Four-Wave mixing (FWM), etc [1], [10].…”