A Mueller-Stokes analysis of the polarization characteristics of a photonic crystal fiber (PCF) with a mechanically induced long-period fiber grating (MLPFG) is presented. Results show that the diattenuation and the polarizance parameters, and the anisotropic degree of depolarization, increase greatly with the LPFG in the PCF. The depolarization index, the Q (M) depolarization scalar metric, the theorem of Gil-Bernabeu, and the degree of polarization, provide consistent results that indicate the existence and the increasing of depolarization effects due to the presence of the LPFG in the PCF. Finally, the polarization dependent loss also increases when the LPFG is present in the fiber for a wavelength illumination centered at 1064 nm. As a conclusion, the PCF with LPFG cannot be described by the Jones matricial formulism. One important result we have found here is that the PCF we employed has an intrinsic anisotropic degree of depolarization.
We present the fabrication and characterization of a micro-displacement sensor using Mach-Zehnder
interferometer in conventional optical fiber SMF28-e. The Mach-Zehnder interferometer uses a
configuration of two long-period gratings (LPG) in series mechanically induced. The Mach-Zehnder
interferometers were made to operate in the region of 1300 nm. As a result the interferometers were
obtained with transmission bands with a bandwidth of 2 nm, extinction ratio of 12 dB and insertion loss of
2 to 3 dB. The characterization of the interferometer was found to be measured displacements up to 500
μm with a resolution of 7 microns, which envisions potential applications of micro-displacement sensor in
the measurement of micro-deformations.
We present the temperature response of a mechanically-induced long-period fiber grating (MLPFG) made in photonic
crystal fiber (PCF) with and without the coating polymer. In both cases, we found a wavelength shift to shorter
wavelengths and a critical decrease of the attenuation peaks. A maximum wavelength shift of 6 nm at 1060 nm was
obtained when the temperature changed from 20 to 80 °C in PCF without the polymer. Whereas, the depth of the
attenuation peaks were dramatically reduced from 12 to almost 2 dB at 1060 nm when the temperature increase from 20
to 100 °C in both experiments. These results are important to consider when MLPFG are applied in a medium with room
A method for tuning the transmission characteristics of arc-induced long-period fiber gratings by local heating is
presented. A traveling burner, produced by the combustion of a mixture of oxygen and butane, locally heats the longperiod
grating producing a wavelength shift of the resonant peaks. We have found that the resonant wavelengths are
blue-shifted during the first 7 round trips of the flame, but when heating process continues the notches shifts toward
longer wavelengths. A fine and long range tuning of the resonant wavelengths up to 120 nm can be achieved without
substantial degradation on the grating characteristics. The process is repeatable and only takes a few minutes.