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Optical pulse generation using an optically injected Nd:YVO4 laser

Kamel, Nada (2015) Optical pulse generation using an optically injected Nd:YVO4 laser. PhD thesis, Prifysgol Bangor University.

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Abstract

This thesis experimentally investigates the use of the optically injected solid state-laser system as a new approach to generate optical pulses with a continuous range of pulse repetition frequency. The construction of the system, the basic requirements and various performance characteristics of different dynamical states resulted from the optical injection are introduced and discussed. One of the objectives of this research is to investigate control over the pulse repetition frequency (PRF) of the nonlinear dynamics of solid state laser, by varying the frequency detuning between the free running injection and the main lasers. For this purpose, the response of the pulse repetition frequency to the changes in the detuning is evaluated for the main dynamical regimes that operate in this system. The results showed a high level of response of PRF to the changes in detuning for the perioddoubling regime and for the limit cycle regime with a correlation coefficient between the PRF and the detuning of around 0.99. A very low correlation coefficient for the same variables, of 0.2 and less are determined in the spiky regime, showing low response to the detuning change. While different correlation coefficients of PRF and detuning were obtained in the quasi-periodic regime. The results revealed a bistable behaviour of periodic and quasi-periodic waveforms in the spiky regime. Pulses with a continuously variable pulse repetition frequency and intensity, are obtained by adjusting the frequency detuning between the frequencies of the injection laser and main laser. The accessible range of pulse repetition frequency in this system is from approximately 200 kHz up to 7.5 MHz. The experimental curves reveal that the relationship between PRF, intensity and detuning is a piecewise function which means that different parts have different properties. The thesis includes also, an evaluation of the frequency instability of the optically pumped solid state laser that leads to stabilise the optically injected solid state-laser system. In this regards, normalised root Allan variance is used as a measure of the instability. The lowest frequency instability of the free running Nd:YVO4 laser was measured to be 10-11 for evaluating time less than 1ms. The frequency instability of the optically pumped Nd:GdVO4 is also evaluated, showing approximately a similar level of instability as Nd:YVO4. The two lasers show a normal level of frequency instability compared to other kinds of optically pumped solid-state lasers. The investigation reveals the existence of many kinds of systematic noise mostly related to the temperature controlling system. This work paves the way to employ the nonlinear dynamics of an optically injected Nd:YVO4 laser as a source of optical pulses.

Item Type: Thesis (PhD)
Subjects: Degree Thesis
Departments: College of Physical and Applied Sciences > School of Electronic Engineering
Degree Thesis
Date Deposited: 21 Aug 2015 08:57
Last Modified: 28 Jun 2016 09:10
URI: http://e.bangor.ac.uk/id/eprint/5267
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