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Propagation of some coherent and partially coherent laser beams
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

In this thesis, we investigate the propagation of some coherent and partially coherent laser beams, including a dark hollow beam (DHB), an elliptical Gaussian beam (EGB), a flat-topped beam and a twisted anisotropic Gaussian Schell-model (TAGSM) beam, through a paraxial optical system or a turbulent atmosphere. Several theoretical models are proposed to describe a DHB of circular or non-circular symmetry. Approximate analytical formulas for a DHB and a partially coherent TAGSM beam propagating through an apertured paraxial optical system are derived based on the generalized Collins formula. Analytical formulas for a DHB, an EGB, a flat-topped beam and a partially coherent TAGSM beam propagating in a turbulent atmosphere are derived in a tensor form based on the extended Huygens-Fresnel integral formula. It is found that after a long propagation distance these beams become circular Gaussian beams in a turbulent atmosphere, and this is quite different from their propagation properties in free space. The conversion of any of these beams to a circular Gaussian beam becomes quicker and the beam spot in the far field spreads more rapidly for a larger structure constant of the turbulent atmosphere, a shorter wavelength and a smaller waist size of the initial beam. Lower coherence and larger twist have a stronger effect of anti-circularization of the beam spot. Our analytical formulas provide a convenient way for studying the propagation of various laser beams through a paraxial optical system or a turbulent atmosphere. The concept of coincidence fractional Fourier transform (FRT) with an incoherent or partially coherent beam is introduced, and the optical system for its implementation is designed. The coincidence FRT is demonstrated experimentally with a partially coherent beam, and the experimental results are consistent with the theoretical results.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , 67 p.
Series
Trita-EE, ISSN 1653-5146 ; 2006-20
Keyword [en]
: dark hollow beam, elliptical Gaussian beam, flat-topped beam, twisted anisotropic Gaussian Schell-model, partial coherent, propagation, paraxial optical system
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4034ISBN: 91-7178-391-1 (print)OAI: oai:DiVA.org:kth-4034DiVA: diva2:10492
Public defence
2006-06-15, auditorium H1, Teknikringer 33, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100831Available from: 2006-06-02 Created: 2006-06-02 Last updated: 2010-08-31Bibliographically approved
List of papers
1. Propagation of various flat-topped beams in a turbulent atmosphere
Open this publication in new window or tab >>Propagation of various flat-topped beams in a turbulent atmosphere
2006 (English)In: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 8, no 6, 537-545 p.Article in journal (Refereed) Published
Abstract [en]

The propagation of flat-topped beams with circular, elliptical and rectangular symmetries in a turbulent atmosphere is investigated. Analytical formulae for the average intensity of various flat-topped beams propagating in a turbulent atmosphere are derived in a tensor form. The formulae derived can easily be reduced to those for flat-topped beams propagating in free space (in the absence of turbulence). The propagation properties of flat-topped beams are studied in detail. We find that a flat-topped beam with circular or non-circular symmetry will evolve into a circular Gaussian beam in the far field under the influence of atmospheric turbulence, which is quite different to its properties in free space. Our method provides an effective and convenient way to analyse the propagation of various flat-topped beams in a turbulent atmosphere.

Keyword
flat-topped beam, propagation, turbulent atmosphere
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24263 (URN)10.1088/1464-4258/8/6/008 (DOI)000238506900009 ()2-s2.0-33745771119 (Scopus ID)
Note
QC 20100831Available from: 2010-08-31 Created: 2010-08-31 Last updated: 2017-12-12Bibliographically approved
2. Propagation of hollow Gaussian beams through apertured paraxial optical systems
Open this publication in new window or tab >>Propagation of hollow Gaussian beams through apertured paraxial optical systems
2006 (English)In: Journal of the Optical Society of America a-Optics Image Science and Vision, ISSN 1084-7529, Vol. 23, no 6, 1410-1418 p.Article in journal (Refereed) Published
Abstract [en]

On the basis of the generalized Collins formula and the expansion of the hard-aperture function into a finite sum of complex Gaussian functions, an approximate analytical formula for a hollow Gaussian beam propagating through an apertured paraxial stigmatic (ST) ABCD optical system is derived. Some numerical examples are given. Furthermore, by using a tensor method, we derive approximate analytical formulas for a hollow elliptical Gaussian beam propagating through an apertured paraxial general astigmatic ABCD optical system and an apertured paraxial misaligned ST ABCD optical system. Our results provide a convenient way for studying the propagation and transformation of a hollow Gaussian beam and a hollow elliptical Gaussian beam through an apertured general optical system.

Keyword
angular-momentum, atomic motion, light-beams, wave-guides, generation, fibers, bessel
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15695 (URN)000237755000017 ()2-s2.0-33745755809 (Scopus ID)
Note
QC 20100831Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2013-11-19Bibliographically approved
3. Propagation of various dark hollow beams in a turbulent atmosphere
Open this publication in new window or tab >>Propagation of various dark hollow beams in a turbulent atmosphere
2006 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 14, no 4, 1353-1367 p.Article in journal (Refereed) Published
Abstract [en]

Propagation of a dark hollow beam (DHB) of circular, elliptical or rectangular symmetry in a turbulent atmosphere is investigated. Analytical formulas for the average intensity of various DHBs propagating in a turbulent atmosphere are derived in a tensor form based on the extended Huygens-Fresnel integral. The intensity and spreading properties of the DHBs in a turbulent atmosphere are studied numerically. It is found that after a long propagation distance a dark hollow beam of circular or non-circular eventually becomes a circular Gaussian beam (without dark hollow) in a turbulent atmosphere, which is much different from its propagation properties in free space. The conversion from a DHB to a circular Gaussian beam becomes quicker and the beam spot in the far field spreads more rapidly for a larger structure constant, a shorter wavelength, a lower beam order and a smaller waist size of the initial beam.

Keyword
gaussian laser-beams, free-space, order, intensity, networks
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15432 (URN)000235424400002 ()
Note
QC 20100831Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
4. Average intensity and spreading of an elliptical Gaussian beam propagating in a turbulent atmosphere
Open this publication in new window or tab >>Average intensity and spreading of an elliptical Gaussian beam propagating in a turbulent atmosphere
2006 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, no 5, 568-570 p.Article in journal (Refereed) Published
Abstract [en]

An analytical formula for the average intensity of an elliptical Gaussian beam (EGB) propagating in a turbulent atmosphere is derived. The spreading properties of an EGB in a turbulent atmosphere are studied. It is found that an EGB will eventually become a circular Gaussian beam in a turbulent atmosphere. This interesting phenomenon is quite different from the propagation of an EGB in free space. The evolution properties are closely related to the parameters of the beam and the turbulent atmosphere

Keyword
laser-beams, z-scan, networks
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15447 (URN)000235532600002 ()2-s2.0-33644925880 (Scopus ID)
Note
QC 20100831Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
5. Propagation of a partially coherent twisted anisotropic Gaussian Schell-model beam in a turbulent atmosphere
Open this publication in new window or tab >>Propagation of a partially coherent twisted anisotropic Gaussian Schell-model beam in a turbulent atmosphere
2006 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 4Article in journal (Refereed) Published
Abstract [en]

Analytical formulas are derived for the propagation of a partially coherent twisted anisotropic Gaussian Schell-model (TAGSM) beam in a turbulent atmosphere. Propagation properties of a TAGSM beam in a turbulent atmosphere are investigated in detail. It is found that a TAGSM beam will become a circular beam in a turbulent atmosphere, and low coherence and larger twist have an effect of anticircularization of the beam spot. The beam spot spreads more rapidly for lower coherence, larger twist, or stronger turbulence.

Keyword
average intensity, laser-beams, space
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15875 (URN)10.1063/1.2236463 (DOI)000239376500017 ()
Note
QC 20100831Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
6. Propagation of partially coherent twisted anisotropic Gaussian Schell-model beams through an apertured astigmatic optical system
Open this publication in new window or tab >>Propagation of partially coherent twisted anisotropic Gaussian Schell-model beams through an apertured astigmatic optical system
2006 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, no 6, 685-687 p.Article in journal (Refereed) Published
Abstract [en]

By expanding the hard-aperture function into a finite sum of complex Gaussian functions, we derived an approximate analytical formula for a partially coherent twisted anisotropic Gaussian Schell-model (AGSM) beam propagating through an apertured paraxial general astigmatic (GA) optical system by use of a tenser method. The results obtained by using the approximate analytical formula are in good agreement with those obtained by using the numerical integral calculation. Our formulas avoid time-consuming numerical integration and provide a convenient and effective way for studying the propagation and transformation of a partially coherent twisted AGSM beam through an apertured paraxial GA optical system. (c) 2006 Optical Society of America.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24262 (URN)000235833400003 ()
Note
QC 20100831Available from: 2010-08-31 Created: 2010-08-31 Last updated: 2017-12-12Bibliographically approved
7. Coincidence fractional Fourier transform implemented with partially coherent light radiation
Open this publication in new window or tab >>Coincidence fractional Fourier transform implemented with partially coherent light radiation
2005 (English)In: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION, ISSN 1084-7529, Vol. 22, no 9, 1798-1804 p.Article in journal (Refereed) Published
Abstract [en]

We introduce the coincidence fractional Fourier transform (FRT) implemented with incoherent and partially coherent light radiation. Optical systems for implementing the coincidence FRT are designed. The results show that the visibility and quality of the coincidence FRT of an object are closely related to the light source's transverse size, coherence, and spectral width. As an example, we numerically study the coincidence FRT of a single slit. (c) 2005 Optical Society of America.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24264 (URN)000231544400010 ()
Note
QC 20100831Available from: 2010-08-31 Created: 2010-08-31 Last updated: 2010-08-31Bibliographically approved
8. Experimental observation of coincidence Fractional Fourier transform with a partially coherent beam
Open this publication in new window or tab >>Experimental observation of coincidence Fractional Fourier transform with a partially coherent beam
2006 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 14, no 16, 6999-7004 p.Article in journal (Refereed) Published
Abstract [en]

The coincidence Fractional Fourier transform (FRT) is implemented with a partially coherent light source experimentally. The visibility and quality of the coincidence FRT pattern of an object are investigated theoretically. The FRT pattern of an object is obtained by measuring the coincidence counting rate between the detected signals passing through two different optical paths. The experimental results are analyzed and found to be consistent with the theoretical results.

Keyword
optical implementation, light
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15926 (URN)000239861100003 ()
Note
QC 20100831Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved

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Citation style
  • apa
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  • modern-language-association-8th-edition
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  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
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