000			03343nam a2200289 a 4500
008			2016
082	0	4	_aTHESES PRESS
100	1		_aButler, Thomas, _eauthor.
245	1	0	_aReal-time characterisation of dynamic laser fields / _cThomas Butler.
264		1	_aCork : _bCork Institute of Technology, _c2016
300			_aix, 248 pages : _bcolor illustrations, graphs, tables. ; _c30 cm
336			_atext _btxt _2rdacontent
337			_aunmediated _bn _2rdamedia
338			_avolume _bnc _2rdacarrier
490	0		_aPh.D - Physical sciences
502			_aThesis (Ph.D.) - Cork Institute of Technology, 2016
504			_aIncludes bibliographical references.
520			_a"Many modern technologies rely on laser devices, in areas such as communications, sensing and imaging. Examination and research into the fundamental operational dynamics of lasers and characterisation of laser performances, are a crucial tool in ensuring the quality and effectiveness of laser-based applications. The development of characterisation tools is an important part of improving upon existing technologies and advancing the next generation of devices. In this work, a real-time multiheterodyne detection technique is developed which allows for the study of dynamically varying pulse trains formed by optical frequency combs. Single-shot complex spectrum analysis is performed with a 50 MHz frame-rate on a series of dynamic amplitude and frequency modulated pulse trains. This high time-resolution characterisation method is the first known multiheterodyne technique to be applied to non-periodic waveforms. A real-time electric field reconstruction technique is also presented, for the characterisation of fast frequency-swept lasers. Phase measurement of the laser field output is achieved for a variety of lasers designed for optical coherence tomography applications. Swept sources with bandwidth of up to ~20 THz, and repetition rates of 200 kHz, are studied. The novel 3x3 fibre coupler-based interferometric method is shown to completely recover the complex electric field, enabling analysis of the spectral, temporal, coherence and dynamic properties of these lasers. Compared to pre-existing time-averaging methods, new experimental results demonstrate the ability to completely characterise the laser sweep and imaging properties in a single-shot, showing both inter- and intra-sweep properties. Finally, an optical random number generator scheme is presented, based on the operation of a turbulent fibre laser. Random bit streams of 1 Tb/s are demonstrated. These results are competitive with many state-of-the-art optical systems utilising more complex generation schemes. Furthermore, it is shown that in the absence of an external optical signal, the inherent electrical noise of a modern high-speed analogue-to-digital converter can be leveraged to provide Tb/s generation rates in a highly simple and cost-effective manner". - (Author's abstract)
650		0	_aLasers. _939105
650		0	_aLaser industry. _939099
650		0	_aFiber optics. _937299
650		0	_aSpectrum analysis. _942802
650		0	_aPulse techniques (Electronics) _9100976
907			_a.b11211210 _b161006 _c161005
942			_n0
998			_ac _b161005 _cm _da _e- _feng _gie _h0
999			_c106383 _d106383