Browse Prior Art Database

Tetrahedrally Coordinated Cobalt Systems as Materials for Tunable Solid State Lasers

IP.com Disclosure Number: IPCOM000115854D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Macfarlane, RM: AUTHOR [+2]

Abstract

Divalent cobalt ions present as tetrahedrally coordinated impurities in solids such as spinels and II-VI compounds, are proposed as the active medium for compact tunable solid state lasers. The advantage of tetrahedral coordination is that the crystal field is very asymmetric which results in a high oscillator strength for d rarrow d transitions and a high stimulated emission cross section. The tetrahedral environment also produces a low crystal field in which the sup 4 T sub 1 (P) level of divalent cobalt has a large energy gap below it, often resulting in weak non-radiative decay and a good quantum efficiency for light emission. In order to have tunable laser action it is desirable to have a vibrational sideband on the electronic optical transition.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Tetrahedrally Coordinated Cobalt Systems as Materials for Tunable
Solid State Lasers

      Divalent cobalt ions present as tetrahedrally coordinated
impurities in solids such as spinels and II-VI compounds, are
proposed as the active medium for compact tunable solid state
lasers.  The advantage of tetrahedral coordination is that the
crystal field is very asymmetric which results in a high oscillator
strength for d rarrow d transitions and a high stimulated emission
cross section.  The tetrahedral environment also produces a low
crystal field in which the sup 4 T sub 1 (P) level of divalent
cobalt has a large energy gap below it, often resulting in weak
non-radiative decay and a good quantum efficiency for light emission.
In order to have tunable laser action it is desirable to have a
vibrational sideband on the electronic optical transition.  In the
case of tetrahedral cobalt systems the vibronic coupling is
moderately strong (Debye Waller factor tilde 3) which produces
phonon sidebands approximately 1000 - 2000 cm sup -1 wide.  This
determines the range of tunability of a laser based on these
materials and provides useful tunability while at the same time
retaining a high peak stimulated emission cross section of tilde
10 sup -18 cm sup 2 .

      An example of the class of materials proposed here is LiGasub
5 Osub 8:Co sup 2+.  It grows from suitable fluxes as octahedra with
naturally parallel (111) faces.  At a concentration of 0.2% Co sup 2+
ions, the abs...