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Sub-Nanosecond Minilaser

#B-520


Sub-Nanosecond Minilasers on the Base of Perspective Media for Spectroscopic and Screening Applications

Tech Area / Field

  • PHY-OPL/Optics and Lasers/Physics

Status
3 Approved without Funding

Registration date
25.05.2000

Leading Institute
B.I. Stepanov Institute of Physics, Belarus, Minsk

Collaborators

  • Technische Universität Berlin / Institute für Optik und Atomare Physik, Germany, Berlin\nUniversity of Applied Sciences/FB Technologie &Management/Rechenzentrum, Germany, Ravensburg-Weingarden\nUniversität Hamburg / Institut für Laser Physik, Germany, Hamburg

Project summary

The state of the art in the field and the impact of the proposed project on the progress in this field.
High efficiency, compactness, reliability, possibility of direct modulation of radiation by applying electronic schemes for drivers are the most attractive advantages of solid-state lasers with diode pumping (DPSSL) in comparison with other types of lasers. In accordance with data of Laser Focus World the DPSSL took first place in the selling growth in comparison to other type of lasers (except for laser diodes), and fifth place of the sell volume at the laser world market.
Recently the great interest of researchers and developers of new laser systems is in the field of microchip lasers. Such systems are sub-miniature DPSSL with the cavity formed by dielectric mirrors deposited directly onto crystal facets. Usually microchip laser consists of one, two, three, or more crystals which are connected together, namely, active element, Q-switch, nonlinear crystals. Q-switch, or passive saturable absorber, is necessary when minilaser is designed for Q-switched regime of operation. Short pulse duration, high intensity, and stability of radiation of Q-switched microchip laser in combination with compactness, reliability, simplicity in usage and relatively low cost define a wide region of their application - as a source of SRS and other nonlinear optical effects excitation in optical fiber for receiving the radiation with extra-broad spectrum, in defect detection systems for semiconductor process technology, in device for chemicals and biological particles detection in atmosphere, including pollution monitoring by LIDARs, in microsurgery and so on. At present time well known minilasers are on the base of neodymium containing active media Nd:YAG, Nd:LSB, Nd:YVO4 and Nd:YLF. The best efficiency of laser action was demonstrated for minilasers with Nd:YAG and Nd:LSB. Unfortunately the growth technology for these crystals of high purity and optical quality is sufficiently complicated and expensive. In this Project the development of minilasers on the base of active media differing the relatively high efficient laser action at ~ 1 micron, and easy, reproducible, and inexpensive growth technology is offered. Double tungstates are also high efficient SRS media due to their structure symmetry. This property considerably extends the range of their application in laser systems.
The main goal of the Project is development, creation, investigation of power characteristics and nonlinear optical dynamics, and application of diode pumped solid-state Q- switched minilasers emitting in infrared (IR), visible, and ultraviolet (UV) spectral regions on the base of perspective laser and Raman active media - double tungstates Nd:KGW and Yb:KYW.
Expected results and their application.
As the result fulfillment of the first part of the Project the microchip lasers with pulse width less than 10-9 s and output radiation parameters:
- wavelength l= 1.06 mm, average power P=100 mW,
- l=1.030…1.050, P=100 mW,
- l=0.53 mm, P=25 mW,
- l=0.35 mm, P=1 mW,
- l=0.26 mm, P=3 mW
will be developed and created.
Visible and UV laser radiation will be obtained by second, third, and forth harmonic generation. During the Project realization the different media for saturable absorber will be used. The laser dynamics of minilasers will be investigated. With the aim of increasing the laser efficiency the processes of the pumping and nonlinear conversion will be investigated by use of Bessel laser beams possessing in comparison with Gaussian beams such features as diffraction-free propagation and high intensity nearby the axis. The comparative analysis of laser characteristics of different active media will be carried out.
The second part of the Project includes the investigation, elaboration and creation the minilasers with stimulated Raman scattering (SRS) self frequency conversion (l=1.13…1.16 и 1.18 mm, P=10 mW; l=1.5 mm, P=0.1 mW), where the active crystals Nd:KGW and Yb:KYW are also SRS active media. Nonlinear dynamics of lasing processes and SRS conversion in minilasers will be studied, their characteristics will be optimized.
In the third part of the Project the developed minilasers emitting in visible and UV spectral ranges will be used in spectroscopic studies of important model organic molecules (porphyrins, metalloporphyrins), related biological compounds (heme proteins), and metalloporphyrin-DNA intermolecular complexes. Main attention will be focused on two spectroscopic techniques - (1) time-resolved r4sonance Raman spectroscopy in nano- and microsecond time domains, and (2) Luminescent spectroscopy.
Thus during the Project realization:

- new fundamental knowledge will be obtained – nonlinear dynamics of generation, SRS self-conversion, and nonlinear conversion of Bessel beams in new laser systems will be studied;
- design tasks connected with elaboration and creation of experimental samples of minilasers with new perspective laser media will be solved;
- applying the created lasers for spectroscopy of biologic objects will be carried out.

Experimental samples of lasers created during the Project fulfillment will be the prototypes of future production of Belorussian laser equipment manufacturers.
Addressing the ISTC objectives. From point of view of military conversion it is very important that a large scientific group including 4 doctors and 10 candidates of sciences which previously worked under military program projects will obtain an opportunity to apply their knowledge and experience to solve the scientific problems for peaceful aims. For achievement of the Project goal it is planned the usage of experimental set-ups and measurement installation of the Institute of Physics, the application of the methods and inventions of the Project authors, including those which were elaborated and created during fulfillment former military programs.
Scope of activities. The work will be fulfilled during 36 months, the total volume of work is 274 person-months.
Competence of the project team.
The scientific group which will perform the Project has a large experience in laser physics, nonlinear optics and spectroscopy and has available the most of necessary scientific equipment.
During last years the Project group fulfilled the researches directly connected to the Project subject. The DPSSLs including microchip lasers on the base of active media Nd:YAG, Nd:KGW, Nd:BEL, Nd:YVO4, Nd:LBGM, Nd:LGNO, Yb:KYW were elaborated and investigated. Some of them have been elaborated for the first time. The best world level results on efficiency conversion were achieved. Preliminary nonlinear optical conversion of laser Bessel light beams was successfully carried out. The laser action in all solid-state diode pumped SRS-laser with self frequency conversion for the first time has been realized, two new types of SRS-soliton were found, the possibility of SRS-generation with super Gaussian statistics was determined. Two-frequency source of radiation for ozone distribution monitoring in atmosphere based on excimer laser radiation SRS-shifter was elaborated. New photo-chemical reactions was observed by means of laser spectroscopy.
Role of foreign collaborators. Theoretical and experimental results received during working out of the Project, as well as created experimental samples of the minilasers will be widely used for investigation in cooperation with the scientific group headed by Dr. S.Kueck (Institut fuer Laser-Physik, Universitaet Hamburg) and with the scientific group headed by Prof. Dr. H.J.Eichler (Optisches Institute, Technische Universitat Berlin).
Computer simulation of nonlinear dynamics of processes in minilasers will be carried out jointly with the computer center headed by Prof. Dr. R.Kragler (agreement on cooperation between Fachhochschule, Ravensburg-Weingarten, Germany, and Institute of Physics of NASB, Belarus) and scientific group headed by Prof. Dr. K.A.Shore (University of Walles).
Technical approach and methodology.
The work on the Project will be based on the results achieved by the authors of the Project in the past three years and methods developed during the fulfillment of these works: development of Nd:KGW and Yb:KYW diode pumped lasers, including microchips; SRS DPSSL with self frequency conversion; experimental and theoretical investigation of BLB sum frequency generation; emission and time resolved spectroscopy of bio-molecules.
The research and applied parts of the Project will be conducted simultaneously, being interdependent and supplementary each other.
During the development of DPSSL minilasers mechanical and optical elements and modules developed and created by the authors of the Project under their works on military programs will be used. That greatly reduces material and intelligent expenses of the offered Project.
Calculation of laser resonators and elements, and computer modeling of laser operation will be carried out on the base of programs, written in “MATEMATICA 4.0”
Elaboration and creation of minilasers will be performed on the base of experience and techniques developed by scientists of the Project group, including those which developed during fulfillment of the former military programs.


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