Design of a pressure sensor of 0–7 bar in fiber optic using MMI methodology

This research shows the possibility of measuring pressure in the range of 0–7 bar and the comparison against 2 commercial sensors. The technique used is based on the multimodal interference in a fiber optic singlemode–multimode–singlemode (SMS) to 1550 nm. The fiber optic is mounted on a plate of stainless steel AISI 316, where the bending of the plate will generate a curvature on the part of the multimodal fiber generating a decoupling of modes and this generates a low intensity to the output of the system.     

Mode-locked fiber laser using an SU8/SWCNT saturable absorber

We report the fabrication of a saturable absorber based on SU8 single wall carbon nanotube (SWCNT) composite material. Thin films with a controllable thickness can be fabricated using a simple and reliable process. These films can be inserted between two FC/APC connectors in order to have an inline saturable absorber. A passive mode-locked laser was built by interleaving the fiberized saturable absorber in an erbium-doped fiber (L-band) ring cavity laser. The laser produces 871 fs pulses with a repetition rate of 21.27 MHz and a maximum average power of 1 mW.     

Extra revivals in cooperative atomic inversion in a cavity

We investigate collective and quantum properties of the atomic inversion of A two-level atoms interacting with a strong quantum field of a single-mode loss-free cavity. The dynamics consists of A fast scales of Rabi oscillations, each featuring collapses and revivals. The first revival of the second quasiharmonic scale can be observed with large cooperativity, demonstrating altogether the existence of the extra sidebands of the resonance fluorescence spectrum. There are also A slow cooperative scales which form the slow envelope of the inversion, which for large cooperativity can split the revivals. For the case of half excited initial atomic state the energy exchange between the field and atomic system is strongly suppressed, and there is an average energy loss by the atoms.     

Fiber-optic sensor for liquid level measurement

A novel (to the best of our knowledge) liquid level sensor based on multimode interference (MMI) effects is proposed and demonstrated. By using a multimode fiber (MMF) without cladding, known as no-core fiber, liquids around the MMF modify the self-imaging properties of the MMI device and the liquid level can be detected. We show that the sensor exhibits a highly linear response with the sensing range and multiplexed operations easily controlled by just modifying the length of the no-core fiber. At the same time, we can measure the refractive index of the liquid based on the maximum peak wavelength shift. We can also use the sensor for continuous and discrete liquid level sensing applications, thus providing a liquid level sensor that is inexpensive with a very simple fabrication process.     

Photorefractive phase conjugation of pulses: A numerical and analytical comparison

We study numerically the temporal behavior of the phase conjugation of a pulse, by a single four-wave mixing grating, in photorefractive media. We solve numerically the time-dependent coupled-wave equations obtained from a currently used generalization of the Khuktarev model, under the standard restriction of undepleted pump and slowly varying envelope approximations. The fully numerical solutions presented here are terminal solutions that do not require solving any intermediate steps such as the reflectivity. However, we compare the numerical reflectivity with its analytical counterpart, when available, and discuss the differences on their predictions of the phase conjugate pulse.Current permanent position at INAOE and on a Sabbatical leave from the Centro de Investigaciones en Optica, Apdo. Postal 948, Leon, Gto. 37000. Mexico.     

Vector soliton fiber lasers

We show by simulations that a nonlinear optical loop mirror with birefringent fiber can have intensity-dependent transmission of vector soliton pulses with a 50/50 coupler. Using this result we propose two mode-locked laser cavity designs.     

Generation of short light pulses under the stimulated Brillouin scattering in fibers with an optimal feedback

The generation of short light pulses (1 ns) in single mode fibers under pumping by wide laser pulses (of a microsecond duration) due to the backward stimulated Brillouin scattering (SBS) is numerically investigated. The influence of the acoustic diffraction is taken into account. The cases of acoustic waveguide and anti-waveguide fibers are considered. For an acoustic anti-waveguide fiber, a dependence of overlap integral S on the acoustic mode number n has a sharp peak in the region of n 100. Computer simulations have demonstrated the energy conversion of the pump wave into short pulses of the signal (Stokes) wave in the case of synchronous pumping. The optimal length of the fiber should be approximately equal to the half-length of the pump pulse. The bypass time of the Stokes pulse of the optimal circuit fiber and the feedback loop must be equal to the repetition period of the pump pulse. An importance of acoustic mode structure of the fiber for the process of forming pulse train in shown. We have found that the acoustic anti-waveguide fibers with a small core (a < 3 m) can be preferable for obtaining the stable train of compressed pulses.