We report the simulation and modeling of a passively Q-switched dual-cavity fiber-laser-doped Yb–Yb. To the best of our knowledge, this is the first time that the traveling-wave model has been applied to the study of the dynamics and to the optimization of the two laser signals produced by the two-cavity laser. An excellent agreement between our simulation results and the experimental measurements published by other researchers is obtained. In addition, we show that the density of the saturable absorber (SA) is a crucial parameter for the optimization of the two laser signals. An increase in the peak power of the two laser signals by an order of magnitude is obtained by increasing the density of the SA.
This study concerns the determination of the diameter of an optical fiber by analysis of a 2D measured diffraction pattern relative to this linear object, falling within the scope of the Fraunhofer approximation. In this approach, when considering a small line-shaped aperture, with a radius α, or a diffractive object placed at the y-axis, an amplitude of the in-line Fraunhofer hologram can be achieved by a mathematical expression, for a given wavelength of the illuminating light λ and a distance z between the particle and the recording plane. The interferometric signal depends on an Airy curve expressed by a Sinc function whose determination of the zeros makes it possible to deduce an argument giving the radius of the fiber. The measurement is carried out for an object-CCD distance equal to z = 60 mm, with a wavelength of illumination λ = 635nm. The zeros of the Airy function appearing in the analytic expression of the interferometric signal allows us to achieve the value of the measured diameter. Knowing that the fiber radius is α = 62.5 μm, the measured value is acquired with an error of 1.7%.
The work developed and presented in this communication, relates to the restitution of frequency chirp of an interferometric signal deduced from a measured diffraction pattern relating to a spherical micro-particle. For this purpose, analysis were achieved by implementing a parametric method with a sliding window. These frequencies allows us to reconstruct the axial position of the corresponding object. The study, achieved in the far field approximation, allows us to validate preceding methods based on simulation results. The principle consists to generate optically in-line diffraction patterns of a spherical particle with radii of 39μm and measured with a microscope ZEISS. The collimated coherent light was generated from a He-Ne laser that the wavelength is λ = 632.8 nm. The generated diffraction pattern was recorded by using a 2D-CCD camera Ophir having 1024 x768 pixels with a pitch of 4.65 μm connected to a computer. Since the variation of the chirp frequency is linear, the knowledge of its variation slop, resulting from a linear fit, enables us to deduce the z-position of the particle. This is achieved with a resolution of 1.2 %.
This work focuses on the simulation and modeling of a passively Q-switched dual-cavity fiber laser doped Yb:Yb, to our knowledge, it is for the first time that the progressive wave model is applied to this type of laser, a good agreement between our simulation results and the experimental results published by another team is obtained, two pulse trains are produced by this laser, the first is at the wavelength of 1064 nm, and the second is at 1100 nm, we also show that certain parameters such as the concentration of Yb ions and their length are an important parameters for the optimization of the two laser signals at 1064 nm and 1100 nm.
A numerical model of an all-fiber Nd3+ laser passively Q-switched with Cr4+ is presented. The repetition rate, average output power, and pulse width have been calculated with the same parameters as those of an experimental setup of another group. We found a qualitative agreement between the two results. The validated model has been used on another proposed setup to investigate and optimize laser parameters. The low and high self-impulse amplitude regimes were found for different Cr4+ ion densities. The optimal efficiency of the high regime was established when the saturable absorber density increases.
An autoregressive method to analyze the fringe pattern observed in holographic interferometry is reported. Considering the impact of a 30 dB signal-to-noise ratio, we have shown that the reconstruction of the simulated symmetric profiles with 3, 4, and 5 fringes produces a maximum error of 0.300, 0.520, and 1.015 rad, respectively. The reconstruction of an asymmetric profile gives a larger error. The method was also applied to a recent fringe pattern. Our results are in qualitative agreement with those obtained using other methods.
We have adapted the point model for the study of an all-fiber laser doped with Nd3+ and Q-switched by a saturable fiber absorber doped with Cr4+. Calculations of the output power of the 1084 nm laser are considered as a function of the pump power supplied by a 790 nm laser diode. The analysis of the simulation results reveals the existence of pulsed, sinusoidal, and dc operating regimes.
Curvature of a multimode optical fiber reduces the numerical aperture and induces radiation losses. We study this phenomenon and we present the "model disadaptation" method to calculate the local numerical aperture and the power attenuation. We exploit the bending effect on the local numerical aperture to propose a new intrinsic optical fiber temperature sensor. The modeling results are experimentally validated for two kinds of optical fibers: a silica-silicone optical fiber and a silica-polymer optical fiber. The simulation and the experimental results are in good accordance and show that the silica-silicone optical fiber sensor can operate between −60 and 152°C with a good response. The silica-polymer optical fiber temperature sensor can sense the temperatures between −249 and 83°C with a good response.
The frequency of the holographic fringe signal is proportional to the measured object deformation or displacement. Fast Fourier transform (FFT) is the most commoly used signal processing technique for analyzing output fringes. One problem with this approach is that a long data acquisition is required to achieve adequate deformation resolution, typically 5 to 10 fringes are needed. We propose using an autoregressive (AR) model to obtain with the same advantages deformation of an opaque object using holographic interferometry. This deformation will be estimated directly from the model parameters. The theoretical and experimental results obtained indicate that the proposed method has a good accuracy by using a small number of fringes.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.