Medicinal
Technologies -
High Power Diode Laser Pumped Fibre Optic Laser
for Medicine and Clinic Service and Removal of Thin
Coatings
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
