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Optimization of Multi-Channel Lasers

#2152


Study of Radiation Properties of Different Types Multi-Channel Lasers and Optimization of their Parameters

Tech Area / Field

  • PHY-OPL/Optics and Lasers/Physics
  • INF-OTH/Other/Information and Communications

Status
3 Approved without Funding

Registration date
27.03.2001

Leading Institute
TRINITI, Russia, Moscow reg., Troitsk

Supporting institutes

  • Institute of the Problems of Laser and Information Technologies, Russia, Moscow reg., Shatura\nMoscow State University / Institute of Nuclear Physics, Russia, Moscow

Collaborators

  • Korea Advanced Institute of Science and Technology, Korea, Taejon\nUniversity of Wisconsin-Madison / Department of Electrical and Computer Engineering, USA, WI, Madison\nUniversity of Potsdam / Center for Nonlinear Dynamics, Germany, Potsdam\nUniversité de Paris VI / Laboratoire pour l'Utilisation des Lasers Intenses (LULI)\nUniversite de Franche-Comte, France, Besancon

Project summary

The objective of this project is study of radiation properties and optimization of schemes construction of different types multi-channel lasers containing an array of gas-discharge molecular lasers, of injection and e-beam excited semiconductor lasers, and of solid-state lasers with lamp and laser excitation at coherent and incoherent addition of the beams of single channels.

At present the problem of powerful and high-quality laser radiation receiving is relevant and its solving has a great importance both for fundamental and applied researches. It‘s well known that increase of output power of any type single-channel laser at the expense of its lateral dimensions increase, leads to decrease of radiation quality. Multi-channel method of lasers design using an array of relatively low-level radiators is free from this defect. It provides a high efficiency of power deposition and heat removal for active medium, allows to increase output power in direct proportion to the channels number and, as consequence, to create a powerful compact lasers with high-quality radiation typical for single laser in an array. On this method the composition is based of well-known developments of different types powerful multi-channel lasers emitting in different spectral ranges.

For working mixture excitation of multi-channel waveguide CO2-lasers with diffusion gas cooling we employ a capacitive ac-discharge with frequency close to 104 Hz. It has allowed to eliminate the power losses of the power supply on capacitive ballast load and to increase total laser efficiency in comparison with dc-discharge, to avoid of the problems of load matching in comparison with rf-discharge and to create a series of effective lasers emitting in a range from 0.5 kW to 10 kW. Our 2-kW laser MTL-2 is being produced in lots and applied in industry for surface hardening of the components of machines and mechanisms, and lasers of the “Genom” – series were found an application in medicine for healing of heart ischemia.

As continuation of these works within the framework of the project, we plan to create a powerful multi-channel CO-laser excited with a capacitive ac-discharge and operated at the temperature of the tubes wall close to the room temperature. Along of effective selection of fundamental waveguide mode it will allow easily and without of losses to match output laser radiation with light-guides existent for given spectral range and characterized by small value of the absorption factor that will provide an effective carriage of laser radiation. Full-scale production of these lasers may be advantageous commercial provision.

For many lasers applications not only total output power but also the possibility of power density increase at radiation focusing is important. If the light fields of single channels of multi-channel laser are not phase-locked its maximal power density increases in direct proportion to N (here N is the number of the channels) in comparison with maximal power density of single-channel laser achieved at similar focusing conditions. In the case of multi-channel laser radiation phase-locking and in-phase distribution of the field across of compound aperture, its maximal power density increases proportionally to N squared.

Studies on multi-channel lasers phase-locking induce a great interest and these studies many scientific centers carry out. For achievement of phase-locked operation of laser array, an optical coupling between single lasers is being introduced or an external signal injection is being implemented. Different types of optical coupling and different methods of its insertion were used in an experiments on phase-locking of the arrays of waveguide CO2-lasers, of semiconductor and solid-state lasers. Single lasers as well as laser arrays were phase-locked also with master oscillator at external signal injection.

The authors of the project proposed were carried out in this direction the series of the foreground works. So, an external Talbot cavity was proposed for phase-locking of periodical laser arrays and sequential analysis of collective modes properties in a such type cavity was carried out. Possibility of coherent addition of radiation of the arrays of e-beam excited semiconductor lasers is shown in a first experiments on phase-locking of two-dimensional laser arrays. New type of multi-channel CO2-amplifier with input from phase-locked multi-channel master oscillator was proposed and studied. The effect of cooperative phase-locking at increase of the detunings of eigen-frequencies of single lasers in an array was detected. The elements of the computer optics were applied successfully for phase-locking and for correction of the far-field pattern of powerful multi-channel CO2-lasers.

Key problem at phase-locking of the fields of multi-channel lasers is achievement of stable in-phase regime operation of its channels because this regime in an arrays with parallel arrangement of the channels provides formation of radiation characterized by small angle pergence determined by sizes of the compound aperture of multi-channel laser. Other important problem is achievement of effective phase-locking or maximally possible decrease of in-cavity losses introduced at optical coupling between channels. Up to now systematic experimental studies are not carried out for solving of these problems.

Within the framework of this project we plane implementation of the cycle of experimental and numerical studies directed for receiving of stable and effective phase-locking of the 2D arrays of waveguide CO2-lasers, of semiconductor lasers with longitudinal and transverse e-beam excitation, of solid-state diode-pumped YAG:Nd chip-lasers, and of the two-element arrays of multi-frequency CO-lasers and lamp pumped pulse-periodical YAG:Nd-lasers. New laser scheme for e-beam excited semiconductor lasers containing a master oscillator and multi-element array-amplifier, and the scheme of two-channel pulse sapphire-titanium amplifier excited with radiation of second harmonic of YAG:Nd-laser will be studied also. These laser devices characterized by high axial brightness of radiation will find an application in many regions of scientific researches, in laser technology, in medicine, in ecology.

During of several last years study of the regimes of synchronization of chaotic oscillations in nonlinear dynamical systems causes a great interest. Possibility of chaos synchronization was shown for the first time for coupled dynamical systems described by Lorenz attractor. Subsequently controlled and synchronized chaos was studied also for other dynamical systems including the systems of optically coupled lasers. Phenomenon of chaos synchronization in a lasers was found an application in information transmission systems.

Our theoretical studies of the regimes of chaotic lasers synchronization carried out earlier allow us within the framework of the project get down to complex experimental and theoretical study of these regimes in a systems of gas-discharge, of injection and solid-state chip-lasers with optical coupling and to probe the possibility of application of the results received in an information systems.

The scope of the work planned is solving of five interrelated tasks. Radiation properties of the arrays of different types of optically coupled lasers will be studied at execution of the project. The regime of mutual lazing of inpidual lasers in an array depends on the value and on the type of optical coupling introduced between them. Alteration of the value of optical coupling will actualize as at coupling between adjacent lasers as well as at global coupling enveloping all lasers of the array. Modern technologies of the arrays manufacture and modern methods for study of laser radiation parameters will employ.

At execution of the project close collaboration with foreign collaborators will actualize. Its role comprises in common discussion and cross-validation of the results received, in common testing of experimental methods and programs debugging, etc.

The project results will be directed only for peaceful purposes in accordance with ISTC principles. As result of project implementation a comprehensive study of radiation properties of the arrays of different types lasers containing gas-discharge, semiconductor and solid-state lasers will be carried out and arrays parameters will be optimized. Experimental samples of lasers with high radiation quality will be created. The results received will promote for expansion of our knowledge about laser dynamics and will find a practical application in scientific researches, in laser technology, in medicine, in ecology, in communication systems and in other regions.


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