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Polymer encapsulated miniature Nd:YAG lasers
Acreo AB, Kista.
KTH, Superseded Departments, Physics.
Acreo AB, Kista.
Acreo AB, Kista.
Show others and affiliations
2003 (English)In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 39, no 20, 1446-1448 p.Article in journal (Refereed) Published
Abstract [en]

A continuation of the previously introduced microstructured silicon carrier concept for diode-pumped solid-state lasers is presented, using novel heat-conducting polymers as a carrier. The most prominent features of the silicon carrier concept are maintained, adding to the mass production possibilities of the inexpensive polymers. The first experiments, using a continuous wave Nd:YAG microchip laser, have given an output power of 2 W at 1064 nm, showing the potential of this new approach.

Place, publisher, year, edition, pages
2003. Vol. 39, no 20, 1446-1448 p.
Keyword [en]
Conductive plastics, Encapsulation, Heat conduction, Microstructure, Microchip lasers, Neodymium lasers
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-8891DOI: 10.1049/el:20030924ISI: 000186031500014OAI: oai:DiVA.org:kth-8891DiVA: diva2:14370
Note
QC 20100901Available from: 2005-12-08 Created: 2005-12-08 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Concepts for compact solid-state lasers in the visible and UV
Open this publication in new window or tab >>Concepts for compact solid-state lasers in the visible and UV
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In many fields, scientific or industrial, optical devices that can be tailored in terms of spectral qualities and output power depending on the application in question are attractive. Nonlinear optics in combination with powerful laser sources provide a tool to achieve essentially any wavelength in the electromagnetic spectrum, and the advancement of material technology during the last decade has opened up new possibilities in terms of realising such devices.

The main part of the thesis deals with the development of compact functional lasers based on nonlinear interaction utilising diode-pumped solid-state lasers and also laser diodes. Efficient frequency conversion into the visible and ultraviolet part of the electromagnetic spectrum has been achieved, using both Nd:YAG and Nd:YVO4 lasers as well as a semiconductor laser as the fundamental light sources. For the nonlinear conversion, periodically poled potassium titanyl phosphate (PPKTP), bismuth triborate (BiBO) and beta barium borate (BBO) have been employed.

In the search for compact and reliable light sources emitting in the visible part of the spectrum, two different approaches have been explored. First, a scheme based on sum-frequency mixing of a diode-pumped solid-state laser and a laser diode of good beam quality. The idea of this approach is to take advantage of the individual strength of each device, which would be the flexibility in terms of wavelength for the laser diode and the possibility to reach high output power from the diode-pumped solid-state laser. Second, by mixing two different solid-state lasers substantially more output power could be generated albeit at a cost of less freedom in the choice of spectral output. As these two light sources had their central wavelength at 492 nm and 593 nm, respectively, they are highly interesting in biomedical applications since they correspond to the peak absorption of several popular fluorophores.

In applications such as lithography, material synthesis and fibre grating fabrication, laser sources emitting in the deep-UV spectrum are desired. An all solid-state 236 nm laser source with 20 mW of average power have been designed and constructed, by frequency-quadrupling a passively Q-switched Nd:YAG laser lasing on a quasi-three level transition.

Also, a novel concept for miniaturising solid-state lasers has been examined. Using a heat-conductive polymer carrier, a generic approach especially suited for mass-production of functional laser devices is presented.

Finally, it has been proven that GRIN lenses can provide a very compact beam shaping solution to standard laser diodes based on the beam twisting approach. This method offers several advantages such as compactness of the beam shaping system, automated assembly in solid-state laser manufacturing due to the shape of these lenses and polarisation preservation of the laser diode output.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. xiii, 76 p.
Series
Trita-FYS, ISSN 0280-316X ; 2006:72
Keyword
nonlinear optics, frequency conversion, visible lasers, ultraviolet lasers, KTiOPO4, BiBO, BBO, quasi phase-matching, birefringent phase-matching, solid-state lasers
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-4223 (URN)978-91-7178-539-8 (ISBN)
Public defence
2006-12-15, FB55, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100903Available from: 2006-12-11 Created: 2006-12-11 Last updated: 2015-03-30Bibliographically approved
2. Diode-pumped rare-earth-doped quasi-three-level lasers
Open this publication in new window or tab >>Diode-pumped rare-earth-doped quasi-three-level lasers
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Many rare-earth-doped materials are suitable for laser operation and this thesis focuses on diode-pumped solid-state lasers employing crystals doped with the trivalent rare-earth ions neodymium (Nd3+), ytterbium (Yb3+) and erbium (Er3+). Especially, the quasi-three-level transitions in Nd and Yb have been studied as well as the eye-safe three-level transition around 1.5 µm in Er.

Quasi-three-level laser transitions in neodymium-doped crystals such as Nd:YAG, Nd:YLF and Nd:YVO4 have received a great deal of interest because they allow for generation of blue light by frequency doubling. For solid-state blue laser sources, there exist numerous applications as in high-density optical data storage, colour displays, submarine communication and biological applications.

Efficient lasing on quasi-three-level transitions at 900¬–950 nm in Nd-doped crystals is considerably more difficult to achieve than on the stronger four-level transitions at 1–1.1 µm. The problems with these quasi-three-level transitions are a significant reabsorption loss at room temperature and a small stimulated emission cross section. This requires a tight focusing of the pump light, which is achieved by end-pumping with high-intensity diode lasers. Nd:YAG lasers at the 946 nm transition have been built and a maximum power of 7.0 W was obtained. By inserting a thin quartz etalon in the laser cavity, the 938.5 nm laser line could be selected and an output power of 3.9 W was then obtained.

By using nonlinear crystals, frequency-doubling of laser light at both 946 nm and 938.5 nm was achieved. Efficient generation of blue light at 473 nm has been obtained in periodically poled KTP, both in single-pass extra-cavity and intracavity configurations. More than 0.5 W was obtained at 473 nm by intracavity doubling. Intracavity second harmonic generation of the 938.5 nm transition gave slightly more than 200 mW at 469 nm.

During recent years, Yb-doped double-tungstate crystals like KGW and KYW have shown efficient laser operation. A comparative, experimental study of the laser performance and thermal-lensing properties between standard b-cut Yb:KGW and Yb:KGW cut along a novel athermal direction is presented. The results show that the thermal lens is about two times weaker and less astigmatic in the athermal-direction-cut crystal, for the same absorbed power. Also, Er-Yb-doped KGW and KYW have been investigated and the fluorescence dynamics have been measured for the Yb (2F5/2), Er (4I13/2) and Er (4S3/2) levels around 1 µm, 1.5 µm and 0.55 µm, respectively.

The influence of upconversion is a detrimental effect both in Nd-doped and Er-Yb-doped lasers. Analytical models starting from rate equations have been developed for these lasers including the influence of upconversion effects. The results of the general models have been applied to 946 nm Nd:YAG lasers and to Er-Yb-doped double-tungstate crystals in order to find the optimum doping concentrations for high gain for an eye-safe laser at 1.53 µm.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. viii, 86 p.
Series
Trita-FYS, ISSN 0280-316X ; 2005:70
Keyword
Optics, laser optics
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-544 (URN)91-7178-220-6 (ISBN)
Public defence
2005-12-16, Sal FD5, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100901Available from: 2005-12-08 Created: 2005-12-08 Last updated: 2010-09-01Bibliographically approved

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