Back to results
US 3,970,960 AGranted
Broadly tunable continuous-wave laser using color centers
AssigneeBell Telephone Laboratories, Incorporated
InventorLinn Frederick Mollenauer
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeBell Telephone Laboratories, Incorporated
InventorLinn Frederick Mollenauer
Estimating the term…
Broadly tunable infrared lasers analogous to dye lasers operating in the visible spectrum are provided by significant improvements upon an F.sub.A (II) color center laser previously demonstrated in a limited way. The improvements include techniques for also using F.sub.B (II) and F.sub.2 .sup.+ color centers and include substantially increased concentrations of the F-centers in regions of pumpable geometry, judicious choice of pumping frequencies and powers and variable, frequency-selecting resonators that are capable of producing oscillation anywhere in the color center fluorescence bands. All solid-state cooling by means of contact between the crystal and a solid heat sink is provided in a way that provides the optical quality needed for efficient operation and for greatest tuning bandwidth of the laser. Use of the color centers in distributed feedback devices is described.
Apparatus for the stimulated emission of radiation of the type comprising a body of an alkali halide crystal having color centers capable of substantial absorption of a particular band of radiation, means for supplying the band of radiation to the crystal to produce a population inversion between radiatively coupled energy levels, and means including reflective surfaces associated with the crystal for stimulating the emission of coherent radiation from the inverted population of color centers, characterized in that the apparatus includes means for cooling the crystal by conduction from the crystal, said cooling means including a substantial solid body contacting said crystal and providing an optical path within said body of negligible loss for the stimulated radiation.
Apparatus for the stimulated emission of coherent radiation comprising a body of an alkali halide containing a substantial concentration of color centers, said color centers being one type selected from the group of types of color centers consisting of F.sub.A (II), F.sub.2 .sup.+ and F.sub.B (II), means for providing heat transfer from said body primarily by solid-state contact, means for exciting said body to provide a population inversion therein by absorption by said selected color centers including means for pumping said body with radiant energy predominantly within the absorption bands of said selected color centers, and means for variably resonating emission from the inverted population to stimulate the coherent radiation.
Apparatus for the stimulated emission of coherent radiation comprising a body of potassium chloride containing lithium as an impurity, said body containing at least 1 .times. 10.sup.17 color centers per cubic centimeter of type F.sub.A (II), means for cooling said body, including a copper heat sink and means for providing a slip-fit mounting of said body to said heat sink with its thinnest dimension being in a direction at Brewster's angle with respect to the laser axis, means for continuously pumping said body in its red absorption band attributable to F.sub.A (II) centers to provide a population inversion in said body, and means for stimulating the emission of coherent radiation from said body, including a resonator including first and second nearly concentrically-spaced focusing reflectors the first of which partially transmits the pump light and the second of which partially transmits the infrared light, and disposed beyond the second of said reflectors, a focusing lens and a diffraction grating rotatable about an axis orthogonal to the laser axis and parallel to the grating plane to promote adjustment of the oscillation frequency.
An optical device of the type comprising a body of an alkali halide having active color centers therein and means for supplying light of well-defined frequency to said body to yield light of another well-defined frequency, said device being characterized by alternating regions of U centers and the active color centers, said U center regions including excess hydrogen to render the body colorless therein, said active center regions and said U center regions having widths orthogonal to their interfaces equal to odd multiples of the wavelength of said emission to provide a distributed feedback effect.
Dependencies are inferred from the claim text.