Juan Castillo Mixcóatl

Optimization of a Fabry-Perot Q-switch fiber optic laser

Optical fiber Q-Switch lasers have been used in a variety of application areas in science as well as in industry owing to their multiple characteristics. A possible application is that owing to their high output power they can be used as pumping sources for supercontinuum generation. Such source can be employed in optical coherence tomography (OCT) focused to dermatology. Therefore it is important to develop sources with emission wavelength that are not injurious to human skin. In the present work erbium doped fiber (EDF) was used owing that its emission wavelength (1550 nm) is adequate for this purpose. The most efficient way of achieving high power in a Q-Switch laser is optimizing all the parameters involved in the pulses generation, such as pumping power, active medium length and modulation frequency. The results show that using a fiber length of 7 meters is possible to get 10 μJ of energy, a peak power of 140 W, an average power of 27.5mW with temporal widths of 500 ns. The laser uses an acousto-optic device to modulate the internal loses inside the cavity. As highly reflecting mirrors, a Sagnac Interferometer and a Fiber Bragg Grating was employed.

Measurement of the dispersion in special optical fibers

Dispersion is a quite important parameter in optical fiber systems, mainly in pulsed lasers where the temporal width of the pulses are affected by this factor. There are many interferometric arrangements to evaluate this parameter and generally, these systems vary the wavelength to obtain information about the refractive index dependency n(λ), which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable light sources with a narrow bandwidth. In this work we propose an alternative method to measure dispersion and we present the results of measurements of special optical fibers, such as microstructured, Er doped, Yb doped, and Er/Yb doped fibers, among others. The experimental arrangement consists of a Mach-Zehnder interferometer, where the fiber under test is located in one of its arms while the air is employed as the reference arm. In order to determine the n(λ) dependency, a wide spectrum light source in the wavelength range of interest was used together with an optical spectrum analyzer. The phase information was evaluated from the measured interferogram. The obtained dispersion values were in agreement with those reported by the fabricant and they were used to calibrate the system in order to obtain non reported values.Dispersion is a quite important parameter in optical fiber systems, mainly in pulsed lasers where the temporal width of the pulses are affected by this factor. There are many interferometric arrangements to evaluate this parameter and generally, these systems vary the wavelength to obtain information about the refractive index dependency n(λ), which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable light sources with a narrow bandwidth. In this work we propose an alternative method to measure dispersion and we present the results of measurements of special optical fibers, such as microstructured, Er doped, Yb doped, and Er/Yb doped fibers, among others. The experimental arrangement consists of a Mach-Zehnder interferometer, where the fiber under test is located in one of its arms while the air is employed as the reference arm. In order to determine the n(λ) dependency, a wide spectrum light source in the wavelength range of interest was used together with an optical spectrum analyzer. The phase information was evaluated from the measured interferogram. The obtained dispersion values were in agreement with those reported by the fabricant and they were used to calibrate the system in order to obtain non reported values.

Experimental arrangement to measure dispersion in optical fiber devices

Dispersion is a quite important parameter in systems based on optical fiber, especially in pulsed emission lasers, where the temporal width is affected by such parameter. Therefore, it is necessary to consider the dispersion provoked by each component in the cavity. There are various experimental interferometric arrangements to evaluate this parameter. Generally, these systems modify the wavelength to obtain information about the n(λ) dependency, which is contained in the interferogram phase. However, this makes the system quite slow and it requires tunable and narrow bandwidth laser sources. In the present work, results obtained from an arrangement based on Mach-Zehnder interferometer where one of the arms is the optical fiber under study, while the reference one is air, are presented. In order to determine the n(λ) dependency, a wide spectrum light source was used in the wavelength range of interest. The phase information was evaluated from the interferometric signal measured by an optical spectrum analyzer.

All fiber laser using a ring cavity

Mode‐locked laser have a number of potential applications, depending on the wavelength and pulse width. They could be used as sources in communications systems for time division multiplexing (TDM) or wavelength‐division‐multiplexing (WDM) as spectroscopic tools in the laboratory for time‐resolved studies of fast nonlinear phenomena in semiconductors, or as seeds for solid‐state amplifers such as Nd:Glass, color center alexandrite, or Ti:Sapphire. Short pulses also have potential use in electro‐optic sampling systems, as a source for pulsed sensors, or as tunable seed pulses for lasers in medical applications. Applications such as optical coherent tomography could take advantage of the broad bandwidth of a mode‐locked fiber laser rather that the temporal ultra‐short pulse width. This work shows the characterization of active mode‐locking all‐fiber laser by using an acousto‐optic frequency shifter to the ring cavity, an erbium doped fiber (EDF) and polarization controllers (PC). The results shows a highly s...

Optical fiber laser of multifrequency emission

The wavelength division multiplexor (WDM) has a great importance in the technology of the communications by optical fiber, is an economic and efficient form, to increase the capacity of transmission by several orders of magnitude, reason why it is desirable to have laser sources of multiple wavelengths in a system WDM, which, according to reported works, have been obtained using diverse types of filters. In this work we presented a laser of multifrequency emission, of Erbium doped optical fiber, tuned with an optical fiber filter. The configuration of the optical filter, presents high stability and low lost by insertion, independence to the changes of polarization, low powers of light entrance, and has an useful spectral wide. It has the advantage to have a simple design and easy manufacture in addition to his low losses.

Optical fiber sensor for the measurement of the pH level using organic dyes deposited by the sol-gel process

Some pH sensors based on optical fibers use organic dyes which are sensitive to the pH levels. Such dyes are deposited over the fiber and they are supported by a matrix, (TiO 2 ) in this case. In this work, we present the results obtained of the fabrication and characterization of an optical fibers sensor with a thin film doped with two different organics dyes (Rhodamine 6G and Coumarin), deposited in a little section of the optical fiber by the SOL - GEL process. It was found that each dye is sensitive to different pH ranges (2 to 12). The fiber optics sensor can be used for the measured of the pH level of aqueous testing solution, and the combination of the dyes is possible to cover a dynamic ranges from 2 to 12. It is also analyzed the sensitivity of the sensor with the Rhodamine 6G and Coumarin dye for different molar concentrations in a range 0.01% to 0.08% and to determine this way the best concentration for the sensor.dyes deposited by the sol–gel process. Juan Pablo Padilla Martínez*, Imelda Santiago Núñez, Georgina Beltrán Pérez, Juan Castillo Mixcóatl, Severino Muñoz Aguirre, Rodolfo Palomino Merino. Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y Rio Verde, Col. San Manuel, Ciudad Universitaria, Puebla, Pue. C.P. 72570, México email: padillamtz7@yahoo.com.mx*

Optical Fiber pH Sensor Using Sol-Gel Deposited TiO 2 Film Doped with Organic Dyes

In the present work there is introduced the fabrication and characterization of a pH sensor based on a multimodal optical fiber that uses a sensing film deposited by the Sol-Gel technique.

Multiwavelength Erbium-Doped Fiber Ring Laser Thermally-Tunable

We propose the wavelength change of a laser of ring cavity, using a filter tunable based on the interferometer of Sagnac with a section of birefringence fiber which response to variations of temperature.

A Water Flow-Meter Using a Fiber Laser and Bragg Gratings

In this work we present a monitoring system to measure the water flux into tubing. The experimental setup uses an optical fiber laser sensor which is constituted by two Bragg grating used like a mirrors.