Design of Ytterbium Doped Fiber Amplifier - Literature review Example

DESIGN OF YTTERBIUM DOPED FIBER AMPLIFIER Name Professor Institution Course Date Literature Review Photo darkening in Ytterbium-doped fibres Ytterbium-doped fibres have a wide use in applications that require simple fibre amplification systems. These systems are also necessary for the pulse amplification of high power. One of the major problems faced by the reliability and high performance of such amplification devices is the mitigation of the active fibre with regard to photo darkening. The manifestation of photo darkening takes place as an increase that temporarily happens in the absorption of broadband. This absorption is situated at a central position were the wavelengths are visible and they have variations with regard to the manner in which fibre manufacturing happens. A portion of absorption for photo darkening extends to certain regions where it results in serious degradation of fibre efficiency with time. Techniques that are used to obtain an accurate measurement of photo darkening characterization should be enhanced to allow for a clear understanding of it causes [21 J. P. Gordon]. This would allow for the formulation of methods and procedures important in realizing extensive commercialization ytterbium-doped silica fibres that are reliable. Previous research studies have been able to present simple techniques to assist in the characterization of photo darkening in single mode as well as double mode with clad Yb-doped fibres. The pumping of a short fibre is done using a brighter source in order to attain uniform and high inversion. The high inversion facilitates the colour centre formation to the high levels of degradation and thus lowering the duration used in performing the analysis [29 R. Paschotta]. With this technique, the measurement of photo darkening can be done using short fibres by avoiding losses at wavelengths that are visible. There has been a previous analysis of the repeatability of the technique of measurement used against the properties of fibre samples and the conditions of pumping.   High-energy Ytterbium-doped fiber amplifiers Sources of high-energy Ytterbium-doped fiber amplifiers find application is several areas, which include spectroscopy as well as laser remote sensing. Various presentations that previously been made with regard to high-energy Ytterbium-doped fibers include single frequency pulsed laser. The laser has four stages of fiber amplification. In the last stage, there is the utilization of a large mode area (LMA) as well as the numerical aperture (NA). The system considers the seed laser with regard to its low power, which results in the modulation of the continuous wave (CW) laser using an acousto-optic modulator (AOM). The repetition frequencies of the modulated pulse of the first two stages of amplification are set in such a way to obtain the minimization of the amplified spontaneous emissions [40 J. Nilsson]. There is then the insertion of another component that plays the role of changing the modulated pulse frequency from by raising its value. The changes play a significant role in the elimination of optical power build up that is released within a bandwidth that is similar to the amplified spontaneous emission filter. In order to ensure that the steepening of pulse does not occur in the stage of amplification, the pre-shaping of the initial acousto-optic modulator takes place. This also includes the demonstration of the last pulse that is shaped into an almost straight top. The raising of the pulse energy takes place by more than 75% through a technique that involves a special shaped pulse [37]. Towards the end, there is the realization of a of a pulse energy of a certain amount at a given duration of pulse at a repetition rate of 100 Hz. Phase-modulated laser pulse from maintaining ytterbium-doped polarization According to the present fusion laser drivers of inertial confinement, the front end for integrated fiber has a wide application towards the generation of polarized laser pulses with phase modulation. The laser pulses are also able to release energies in terms of several thousands of joules. With regard to consideration of various projects and research study activities, the design of pulse amplifier takes place with the use of optical components that are able to maintain polarization. The amplification process involving phase-modulated pulses is subjected to an experimental demonstration through ytterbium-doped large area mode of fiber amplifier [35]. The energy of the pulse is subjected to an amplification of about 4 kilo joules, which is free from stimulated scattering and pulse distortion. The degree of modulation after carrying out optical compensation for wave plates is not more than 6% due to the diffraction limitation brought about by mode field of the output. Several developments with regard to fiber laser are associated with mode-locked Ytterbium. The developments occur in short ultra-pulse generation systems having ytterbium-doped fiber lasers. Previous research studies on this subject have involved the technical challenges and basic properties of single mode and mode lock fiber lasers. This also includes the operation of techniques that aid in the achievement of high peak power levels [35]. The studies have also demonstrated high energy levels of mode locked fiber laser with regard to photonic crystal fiber that features shorts lengths of absorption as well as large mode core. An Ytterbium-doped fiber laser (YDFL) that is efficient in its operation can be demonstrated with the use of a fiber Bragg grating (FBG). This Ytterbium-doped fiber (YDF) is obtained from components that are manufactured by depositing of porous layers. These layers consist of certain elements that play an important role when functioning in conjunction with a solution doping method. The fabricated Ytterbium-doped fiber laser consists of components that are useful in the absorption of 7.55 dB/ m at 984 nm. The laser of the fiber displays a maximum efficiency of 55% with a power threshold from the pump measuring up to 18 mW with the help of fiber Bragg grating. This measurement also considers the use of a Fresnel reflection, which brings about the formation of a linear cavity resonator. The threshold and efficiency can be subjected to a comparison with similar Ytterbium-doped fiber laser configurations using a commercially available Ytterbium-doped fiber. When it comes to comparing the photo darkening process in Ytterbium-doped fibers with other fibers, the development of photo darkening is analyzed with regard to two different areas of ytterbium-doped fibers. In order to realize an acceleration of this process, the use of cladding pumping is employed to achieve uniform and effective inversions. In addition, the measurement and comparison of intensity profiles take place in efforts that are aimed at detecting the possibilities of radial variations in the losses that are introduced. Research studies on the losses experienced in ytterbium-doped fibers are associated with the heating that takes place in a photo-darkened fiber [10]. The photo darkening takes place as result of further increase in losses experienced and which is attributable to the broadening of the absorption spectrum, which is dependent on temperature. The introduction of permanent heat raises the level of loses experienced is an indication of the existing intermediate state of energy levels in the Ytterbium-doped fiber mechanism. Further, there is the application of the energy curve technique to realize the derivation of the energy that is introduced due to defects. Previous works in this area of research study have been able to explore the synchronization of laser between various levels of high-power fiber laser [34 A. Lau and]. In this case, the generation of Nano second pulses takes place through a long cavity that of ytterbium-doped fiber laser. This is then synchronized with mismatch in cavity due the enhancement of resonance as well as the modulation of cross absorption in additional earth doped fiber. The use of two stages in the pre-amplification of Ytterbium-doped fibers and double clad fiber results in the synchronization of nanosecond pulses. References [26] Johnson, L. F. (1963). Optical Maser Characteristics of Rare‐Earth Ions in Crystals. Journal of Applied Physics, 34(4), 897-909.‏ (Johnson, 1963) [33] Lau, A. P., & Kahn, J. M. (2006). Design of Inline Amplifier Gains and Spacings to Minimize the Phase Noise in Optical Transmission Systems. IEEE/OSA Journal of Lightwave Technology, 24(3), 1334-1341. doi:10.1109/JLT.2005.863285 (Lau, Kahn & others, 2006) [35] Limpert, J., Schmidt, O., Rothhardt, J., Schreiber, T., TŘnnermann, A., Ermeneux, S., ... & Salin, F. (2006). Extended single-mode photonic crystal fiber lasers. Optics express, 14(7), 2715-2720.‏ (Limpert et al., 2006) [15] Luo, Z., Ye, C., Sun, G., Cai, Z., Si, M., & Li, Q. (2007). Simplified analytic solutions and a novel fast algorithm for Yb< sup> 3+-doped double-clad fiber lasers. Optics Communications, 277(1), 118--124. (Luo et al., 2007) [29] Paschotta, D. (2014). Encyclopedia of Laser Physics and Technology - double-clad fibers, cladding pumping, cladding-pumped fiber, high power, fiber lasers, amplifiers. Rp-photonics.com. Retrieved 10 August 2014, from http://www.rp-photonics.com/double_clad_fibers.html. (Paschotta, 2014) [37] Pask, H. M., Carman, R. J., Hanna, D. C., Tropper, A. C., Mackechnie, C. J., Barber, P. R., & Dawes, J. M. (1995). Ytterbium-doped silica fiber lasers: versatile sources for the 1-1.2 μm region. Selected Topics in Quantum Electronics, IEEE Journal of, 1(1), 2-13.‏ (Pask et al., 1995) Read More