In this paper we shows the results obtained to fabricate and implement Mach-Zehnder interferometers of
conventional fiber optic using Long Period Fiber Gratings (LPFG´s) which were developed by electric arc
technique. We obtains this type of interferometer when we fabricated two LPFG’s in series or in cascade with the
same characteristics such as number of discharges and the same period, placing them in cascade separated by a
distance which three times the length of the LPFG. The application which was given at interferometer fabricated
was as a liquids sensor, volume sensor of liquids and micro-displacement sensor. The sensors of liquids and liquids
volumes were placed in a container in which the interferometer is fixed so that results of measurements are only by
incorporating each of the liquid and not by some external movement. The sensed fluids were: water, alcohol and
solution (water with sugar). Final length of the interferometer is between 4 to 6 cm. We analyze the results obtained
to when a section the Mach-Zehnder interferometer is displaced in of the order of microns. The variations observed
in transmission spectra obtained from each of the sensors mentioned, show changes in the amplitude and the
attenuation peak of the interferometer was displaced.
We study numerically and experimentally multiple-wavelength operation of an erbium-doped figure-eight fiber laser
including a multiple-bandpass optical filter formed by two concatenated fiber tapers. Both continuous-wave and pulsed
operations are considered. In the continuous-wave regime, stable long-term operation at multiple closely spaced
wavelengths is only obtained if fine adjustments of the cavity losses are performed. Under these conditions,
simultaneous lasing at up to four wavelengths separated by 1.5 nm was observed experimentally. Tunable single-wavelength
operation over more than 20 nm is also observed in the continuous-wave regime. In the passive mode
locking regime, numerical simulations indicate that mechanisms involving the filter losses and the nonlinear
transmission characteristic of the NOLM contribute in principle to stabilize dual-wavelength operation, allowing less
demanding cavity loss adjustments. In this regime, the problem of synchronization between the pulse trains generated at
each wavelength adds an additional dimension to the problem. In presence of cavity dispersion, the pulses at each
wavelength tend to be asynchronous if the wavelength separation is large, however they can be synchronous in the case
of closely spaced wavelengths, if cross-phase modulation is able to compensate for the dispersion-induced walkoff.
Experimentally, fundamental and 2nd-order harmonic mode locking was observed, characterized by the generation of
noise-like pulses. Finally, a regime of multi-wavelength passive Q-switching was also observed. We believe that this
work will be helpful to guide the design of multiple-wavelength fiber laser sources, which are attractive for a wide range
of applications including Wavelength Division Multiplexing transmissions, signal processing and sensing.
We reported Supercontinuum (SC) generation in standard telecom fiber using picosecond pulses of microchip
laser. The pulses width is 700 ps at 1064 nm, using 57 m long of standard fiber, and the spectra extend from 700 to
above 1700 nm, some 100 nm further into the visible. The physical processes leading to the formation of the continuum
spectrum were studied by monitoring the growth of the SC while increasing the input power. The coupling efficiency of
ours experimental setup between the microchip laser and the telecom fiber helped us to obtain this wide spectrum.
In this work we study experimentally and numerically a passively mode-locked figure-eight fiber laser that includes a
polarization-imbalanced Nonlinear Optical Loop Mirror (NOLM), whose switching power can be adjusted through a
wave retarder plate. The laser emits broadband noise-like pulses with a bandwidth that can exceed 50 nm. The pulses are
actually sub-nanosecond wave packets with an inner fine structure of sub-ps pulses with random amplitude and duration.
The duration of the pulses as well as their spectral width can be adjusted through the variation of the NOLM switching
power. Numerical simulations are in good agreement with experimental results, confirming in particular the strong
dependence of the pulse properties on the value of the NOLM switching power, although NOLM switching alone does
not explain the appearance of the noise-like pulsing mode. The properties of this kind of pulses, like their wide
bandwidth and energy, make them attractive for applications like supercontinuum generation and metrology.
In this paper we show numerically how a Gires-Tournois etalons (DGTE) is used to flatten
the gain spectrum of an erbium-doped fiber amplifier. A broadband amplifier with uniform
gain over 40-nm with a residual gain <2-dB is presented.
In this work we study experimentally a novel passively mode-locked erbium-doped figure-eight fiber laser based on a
polarization-imbalanced Nonlinear Optical Loop Mirror (NOLM). The NOLM operation strongly depends on the
polarization state at its input. In this experiment, the input polarization state is set to linear, and its orientation is
controlled through a half-wave retarder plate. The variation of the input polarization angle allows adjusting the NOLM
switching power over a wide range. In this work we show experimentally that this adjustment makes it possible to tune
the spectral bandwidth and the temporal properties of the generated pulses over a wide range.
We propose and study experimentally a novel passively mode-locked figure-eight fiber laser scheme based on a
polarization-imbalanced Nonlinear Optical Loop Mirror (NOLM). In contrast to conventional power-imbalanced
structures, the NOLM used in the proposed laser relies on a difference of nonlinear polarization rotation between the
counter-propagating beams to provide switching. In this experiment, the polarization state at the NOLM input is set to
linear. By controlling the polarization orientation at the NOLM input through a half-wave retarder plate, it is possible to
adjust the NOLM switching power. This property of the NOLM is attractive in the frame of a figure-eight laser. Firstly,
the switching power can be readily set to a value ensuring stable mode-locking operation, without having to cut into the
loop and modify the NOLM length. On the other hand, we observed that stable pulsed operation is maintained over a
certain range of the NOLM input polarization angle, whereas the pulse properties vary over that range. In particular, the
spectral width varies from 16 to 52 nm over that range. This spectral variation is associated with a variation of the pulse
temporal properties. This result can be explained by the fact that the input polarization angle allows controlling the
critical power of the NOLM, which in turn affects the pulses characteristics. The proposed device thus offers a
convenient way to adjust the pulses properties (in particular their spectral bandwidth and duration), simply by controlling
the angle of a wave retarder, a property which is attractive for some applications.
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