Rockwell International Corporation

Boeing North American, Inc.

Mark J Rosker

Patricia H Cunningham

Leslie F Warren, Jr

Mark D Ewbank

Henry O Marcy, 5th

William R Christian

Ian C McMichael

Peter Gunter

A family of cesium-germanium halide salts have utility as nonlinear optical crystals in applications including electro-optics and optical frequency conversion. These salts have the general formula CsGeCl.sub.x Br.sub.y I.sub.z, in which x, y, and z equal 0 through 3, inclusive, and where x+y+z=3. In contrast to well-known oxygen-containing materials, such as LiNbO.sub.3, these cesium-germanium halide salts exhibit optical nonlinearity with an extremely wide transparency range (without significant absorption) at wavelengths from about 0.4 .mu.m to greater than 25 .mu.m (covering the entire MWIR and LWIR regions). Based on Ge.sup.2+ ions, these halides have non-centrosymmetric perovskite structures. The halide ions form a strongly coordinating octahedral environment about the Ge.sup.2+ ions and resist migration in an electric field. The Ge2+ ions, however, are shifted slightly off center in the tetragonal phase, leading to a net electric dipole moment in each unit cell. The alignment of these dipole moments into ferroelectric domains can be controlled through applied electric fields. By aligning all dipole moments into a single ferroelectric domain, these cesium-germanium halides have utility for electro-optic and birefringently phase-matched frequency conversion devices. Alternately, periodic poling of the ferroelectric domains allows these materials to be used for quasi-phase-matched frequency conversion. Cesium-germanium halide salts, which can be isolated from aqueous solutions as salts of GeX.sub.3 .sup.- anions, are water-soluble, which facilitates large-aperture crystal growth.

Cesium-germanium halide salts forming nonlinear optical crystals

A nonlinear optical material includes a noncentrosymmetric crystal of an anionic boron complex salt containing a cation and at least one organic ligand coordinated to a boron atom. The nonlinear optical crystal may consist of a compound having the formula A[BC.sub.2 ] where A is a monocation, B is boron, and C is the organic ligand, or a compound having the formula A[BC.sub.2 ].sub.2 where A is a dication, B is boron, and C is the organic ligand. The organic ligands may also be organic molecules having .alpha.-dihydroxy functionalities. Furthermore, the organic ligands may be selected from the group consisting of .alpha.-hydroxy carboxylic acids and 1,2-diols or from the group consisting of d-malic acid, d-lactic acid, d-tartaric acid, dimethyl-d-tartrate, diethyl-d-tartrate, l-malic acid, l-lactic acid, l-tartaric acid, dimethyl-l-tartrate, diethyl-l-tartrate, and ethylene glycol. The anionic boron complex may be selected from the group consisting of boro-di(l-malate), boro-di(l-tartrate), boro-di(l-lactate), boro-di(diethyl-l-tartrate), boro-di(methyl-1-tartrate), boro-di(d-tartrate), boro-di(d-lactate), boro-di(diethyl-d-tartrate), boro-di(dimethyl-d-tartrate) and boro-di(ethylene glycolate). The cation may be selected from the group consisting of alkali metals, alkaline earth metals, ammonium ions, and Group 2B dications. The cation may be further selected from the group consisting of lithium, sodium, potassium, the ammonium NH.sub.4.sup.+ ion, the guanidinium C(NH.sub.2).sub.3.sup.+ ion, calcium, and zinc.

Semi-organic crystals for nonlinear optical devices

A pulsed diode ring laser gyroscope and method of modulation are provided to greatly reduce the occurrence of frequency locking in optical gyroscopes at low rotational rates. One or two optical diodes serve as optical amplifiers for a pair of counterpropagating optical pulses circulating in an optical ring resonator. The amplifiers are driven twice each round trip (once for each pulse) using pulses much shorter than the round trip time. The short optical pulses overlap in regions of the resonator generally isolated from light scattering elements. The pulses are produced by gain switching the optical amplifiers with an electrical current pulse train having a fundamental period synchronous with the optical round trip time in the resonator cavity. With this modulation scheme, the diodes can be thought of as gates that open twice each round trip-once for each of the counterpropagating pulses. During each on time, the diodes amplify only a clockwise or counterclockwise pulse. Backscattered light from any optical element, which is not coincident with either of the pulses, is absorbed by the amplifiers.

Pulsed diode ring laser gyroscope

Growing community of inventors

Newbury Park, CA, United States of America

Mark J Rosker