Introduction

Fibre lasers based on active glass fibres are finding wide application in engineering and are convenient in use. In these lasers an activised glass fibre is both a source of laser emission and an element enabling to transmit this emission to the required place. The active element can be formed of a fibre bundle, which provides irradiation of several objects simultaneously. Recently fibre lasers pumped with a pulse gas discharge lamp have been designed. The laser head in such lasers comprises of a glass tube with a discharge lamp inside it and an activised fibre coiled around it. These lasers have bulky and expensive systems of electric lamp pumping and head water cooling.

These systems reduce the fields of application of such lasers, increase their cost, and bring down their consumer and commercial value. The use of semiconductor lasers as a pumping source of fibre lasers could result in decrease of overall dimensions and weight of the power unit, and elimination of the cooling systems. The application of resonance pumping improves the efficiency of light pumping energy. Besides, the efficiency of semiconductor lasers reaches 50%, ten times as much as the efficiency of discharge lamps. The use of injection lasers with different wavelengths on one chamber and active fibres doped with various rare-earth elements, allows to create multiwave fibre laser with one chamber. In the framework of this project, it is proposed that a miniature be created which is highly efficient, competitive, having high customer- and commercial-value, single or double-wave fibre emission source based on the fibre, activated by rare-earth elements. This project is aimed at the development, creation, advertising and organisation of production of compact, highly efficient and easy-to-use solid-state lasers (including double-wave ones) based on the fibres, activated by Er and Nd ions. As a pump source, semiconductor injection laser arrays would be used. The expected efficiency of pumping would reach 5-10%. The expected parameters of the proposed laser: Wavelength 1060nm and 1540nm, 2930nm Pulse duration 0.15 - 1.5 ms Average output more than 8W To provide optical pumping there must be semiconductor laser with the wavelength 800-860 nm (for laser wavelength-1060nm) and 940-980 nm (for laser wavelength 1540 and 2930 nm).

The necessary emission power of arrays makes up to 80 W at the efficiency of conversion of light energy to laser energy of 10%, having 0.5 W from an LD chip with the dimensions 0.1*0.4*0.5mm3, and the array consisting of 160 chips. A new model of CW semiconductor laser diode (MOCVD) with the power upto 1W has been designed. The key element to be developed in the project will be Nd:glass and Er:glass fibre laser pump chamber. Using glass with luminescent centres activated with ions of rare-earth elements, neodymium or erbium, makes it possible to manufacture glass fibres, which being irradiated by the light of a pump tube, generate stimulated emission with the wavelength of 1060 or 1540 nm respectively.

The fibres laser pump chamber is made in the form of a cylinder box of standard size, consisting of a bundle of activated glass fibres, reflector, pump tube and cooling system. The chamber is installed under the control panel of the main medical laser with fibre output to a surgical operation area. The chamber can operate both in single pulse mode and in the mode of repeating pulses. At generation pulse duration of 100-120 us, output power makes up about 0.6-0.7 J at the wavelength of 1060 nm. In this case the emission power density is 10 MW/sq.mm. Incase of repeating pulses with the frequency of 10-20 Hz, the average power is 15-18 W (Er activated fibre - 6-8 W). At the wavelength of 1540 nm the output power makes up about 0.3-0.4 J at generation pulse duration of 100-200 us. The use of a bundle of Er and Nd activated glass fibres allows to receive the output of emission with two wavelengths of 1060 and 1540 nm. The design of the fibre laser, having a laser emission output from the end of a freely flexible bundle of fibres is convenient for application in medicine, scientific research and for technological purposes.

Area of Application: Medicine, cosmetics, micro-surgery, stomatology Laser welding and soldering cutting, engraving Removal of thin coatings by laser beam Ignition of internal-combustion engines

Advantages: Currently there is a growing demand in powerful small laser medical units. The small laser units for medical purposes operating with two and more wavelengths are not available today in the market. Besides, existing small laser diode systems do not feature enough peak optical power, which sharply limits possibilities of their application.

Contact:

Asian and Pacific Centre for Transfer of Technology
APCTT Building
C-2 Qutab Institutional Area
P.O.Box - 4575
New Delhi - 110 016
Tel : 91-11-26966509
Fax : 91-11-26856274