Search results for "fiber"
showing 10 items of 2343 documents
Glowing optical fiber designs and parameters
1997
Side-emitting optical fiber designs and main parameters have been studied. A simplified model to describe emission of the 'glowing' fiber is developed. Basic expressions for the emission parameters as functions of the input radiation intensity, distance along the fiber axis and scattering efficiency longitudinal distribution are given for several design modifications. The model assumptions have been checked experimentally by testing silica core side-glowing optical fiber samples.
Long period gratings formed in depressed cladding fibres
1997
There has been a significant interest in long period gratings, primarily due to their applications in gain-flattened erbium doped fibre amplifiers [1]. Up till now, cladding modes supported by the glass-air interface of an optical fibre have been used in a forward mode coupling scheme involving also the guided fundamental mode of the optical fibre. Here we propose an alternative technique. In a single mode depressed cladding fibre of an appropriate design (an example is given in fig. 1), the higher order LP11 mode can be made to be a leaky mode in such a structure, i.e. it can propagate for a short length before being stripped off the high index region beyond the depressed cladding. This en…
Visible Light Generation and Its Influence to Supercontinuum in As2S3 Microstructured Fiber
2011
We demonstrate visible light generation in As 2 S 3 microstructured fiber for the first time. It limits the spectral range of supercontinuum. The visible light generation can be avoided by designing the fiber for the single-mode operation.
Acousto-optic Modulators Based on Flexural Acoustic Waves and its Application to Mode-locked Fiber Lasers
2014
Acousto-optic modulators based on flexural acoustic waves and its application to implement active mode-locking in fiber lasers is reported. Optical pulses as short as 25 ps temporal width were obtained at 2.46 MHz repetition rate.
'SMART laser', Development of laser sources integrating an optimized functioning via a process of learning
2022
Ost commercially available mode-blocking lasers provide a unique pulse regime to the user, driven only by a simple switch. To solve certain problems, it would be advantageous to increase the possibilities of pulse adjustment in many areas of application, from micro-machining to wavelength conversion. One way to increase the degrees of freedom of a laser cavity is to incorporate into it a saturable absorbant with adjustable parameters, as with non-linear polarization evolution devices (NPEs). The absence of an analytical relationship between the adjustable cavity parameters and the characteristics of a generated pulse can be circumvented by the use of scalable algorithms, well suited to mult…
Evolutionary algorithm for fiber laser in ultrashort pulse regime
2016
This thesis deals with the generation of ultrashort pulses within a fiber laser cavity through the automatic optimization of its parameters by an evolutionary algorithm. The interest of this subject comes from the difficulty to systematically explore dynamics in a large domain of experimental parameters. We have shown that it is possible to implement an evolutionary algorithm on fiber laser cavity with appropriate precautions. We have experimentally demonstrated for the first time the mode locking of a laser cavity only using the optimization of polarization controllers through an automatic and self-learning procedure. We also have demonstrated that selecting the mode locking from it radio-…
Synthesis of silacyclopent-2-en-4-ols via intramolecular [2 + 2] photocycloaddition of benzoyl(allyl)silanes
2019
Organosilicon compounds are versatile units with a wide range of uses from medicinal chemistry to the field of organic electronics. An unprecedented method for the synthesis of novel diaryl-substituted silacyclopentenols via blue-light promoted intramolecular [2 + 2] photocycloaddition of acyl silanes is herein disclosed. Additionally, the present findings demonstrate the influence of the olefin substituents in controlling the regioselectivity of the intramolecular Paterno–Buchi reaction, providing silacycles different from previously reported ones. The high degree of functionalization of these compounds makes them attractive precursors to other synthetically challenging silacyclopentanes.
Determination of the facial/oral alveolar crest using RF-echograms. An in vitro study on the periodontium of pigs.
1989
Abstract This study is a part of a research project in which we have been investigating the use of the ultrasonic pulse echo technique as a means of determining in vivo the facial/oral alveolar crest precisely and routinely. Here, RF-echograms are presented, showing the facial/oral periodontium of pigs. These echograms have been produced using a focussed 20 MHz transducer and a special design of an ultrasonic measuring and analysis system. In one series of measurements on macerated periodontia of pigs we found out that RF-echograms characteristic of a particular level of the facial/oral pericrestal aspect can be achieved. Based upon these results, we succeeded in determining exactly the hei…
Ultrasonic B-scans of the facial/oral periodontium in pigs.
1989
In vitro ultrasonic scans of the oral/facial periodontium of pigs were obtained using a special experimental design and with the help of a newly developed ultrasonic measuring and analysis system. These two-dimensional images distinguish themselves from the one-dimensional RF-echograms and A-scans in that they enable the viewer to have a quick overview of the relationship between different interfaces in a scanned sector. A selection of ultrasonic B-scans proves that the scanned tissues such as gingiva, bone, periodontal ligament, tooth surface and even structures of the inner part of the tooth may be clearly imaged and distinctly differentiated. Furthermore, we demonstrate with manipulation…
Reimplantation: clinical Implications and outcome of dry storage of avulsed teeth
2010
Reimplantation refers to the insertion and temporary fixation of completely or partially avulsed teeth that have resulted from traumatic injury. Reimplantation of an avulsed tooth depends on certain clinical conditions like phy- siological status of periodontal ligament (PDL), the stage of root development and the length of extra oral time. Depending on the patient’s age, retention of the permanent incisor can maintain the aesthetic appearance, occlusal function and alveolar ridge height. Though the risk of progressive replacement resorption and subsequent tooth loss is high after a long dry storage, reimplantation makes a provision for an aesthetically acceptable permanent prosthesis at a …