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Material System for Molecular Beam Epitaxy Preparation of Waveguide Lasers

IP.com Disclosure Number: IPCOM000116262D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Farrow, RF: AUTHOR [+3]

Abstract

Disclosed is a material system adapted to the production of planar waveguide lasers by Molecular Beam Epitaxy (MBE). The waveguide configuration is particularly advantageous when using a nonlinear up-conversion pumping scheme since the confinement of the pump light over a long (~ 2cm) path and the good overlap between excited and lasing volumes that can be achieved makes for an efficient laser. It can also be used in the fabrication of conventional lasers. Up-conversion lasers are potentially useful sources of blue-green light pumped by near infrared sources. They have been operated in bulk crystals at reduced temperatures and in glass fiber waveguides at ambient temperature.

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Material System for Molecular Beam Epitaxy Preparation of Waveguide
Lasers

      Disclosed is a material system adapted to the production of
planar waveguide lasers by Molecular Beam Epitaxy (MBE).  The
waveguide configuration is particularly advantageous when using a
nonlinear up-conversion pumping scheme since the confinement of the
pump light over a long (~ 2cm) path and the good overlap
between excited and lasing volumes that can be achieved makes for an
efficient laser.  It can also be used in the fabrication of
conventional lasers.  Up-conversion lasers are potentially useful
sources of blue-green light pumped by near infrared sources.  They
have been operated in bulk crystals at reduced temperatures and in
glass fiber waveguides at ambient temperature.  A planar or 1-D
crystalline waveguide geometry may enable the temperature of
operation of crystal up-conversion lasers to be increased to room
temperature.  In designing a material system for waveguide
fabrication by MBE, it is necessary to choose materials that exhibit
a good lattice match between waveguide layer and substrate, to have a
refractive index difference between the guide and substrate which
allows single-mode guiding at the wavelengths desired and for which
the guide material can be deposited from the vapor phase without loss
of stoichiometry and with low defect structure.  The system of  'LaF'
sub '3' doped with rare-earths, on a (111) oriented substrate of
'SrF' sub '2', satisfies these criteria.

      It has been shown (1) that 'LaF' sub '3' can be deposited by
MBE as high-quality thin layers on suitable substrates since this
material retains its stoichiometry by existing in the gas phase as
the 'LaF' sub '3' molecule.  Crystalline 'LaF' sub '3' is hexagonal
and grows with its c-axis normal to the film plane on suitably
oriented hexagonal or cubic substrates.  For waveguide laser
applications, this substrate must have a higher refractive index than
the 'LaF' sub '3' guiding layer.  (111) oriented cubic strontium
fluoride ('SrF' sub '2') is chosen here for the substrate material
because the lattice match between the hexagonal array of lattice
sites in the (111) planes (4.101A) and and the hexagonal lattice of
'LaF' sub '3' (4.149A) is very good...