The harmonic generating properties of potassium lanthanum nitrate (KLN) and potassium cerium nitrate (KCN) are described. These crystals have much larger nonlinear coefficients than potassium dihydrogen phosphate (KDP) and are nearly noncritically phase matched at room temperature for Type I frequency doubling of 1.064- mu m light, and for Type II doubling of light near 0.95 mu m. Thus, these crys...

We have experimentally determined the spectrally noncritical phase-matching behavior of type I frequency doubling in potassium dihydrogen phosphate (KDP) and its dependence on deuteration level in partially deuterated KD*P. Our results are in agreement with predictions based on available refractive-index data. The first-order wavelength-sensitivity parameter partial derivative-DELTA-k/partial derivative-lambda for type I doubling of 1.053-mu-m light vanishes for a KD*P crystal with a deuteration level of 12 +/- 2%. Calculations of this effect in other KDP analogs are presented, and the possibility of finding materials that have spectrally noncritical behavior for other phase-matched processes is discussed.

The development and operation of a kilowatt scale KD(asterisk)P second harmonic generator is described. The design utilizes a simple and compact two-plate alternating-Z configuration with a transverse thermal gradient. The calculated single pulse conversion efficiency is between 50 and 75 percent for beams whose divergence is up to 15 times the diffraction limit. Offline subaperture tests demonstrated that the effect of induced thermal gradients on conversion efficiency was less than 5 percent for optical loads expected for kilowatt operation. Full aperture tests with a 300 watt average power Nd:glass zigzag slab laser gave conversions of 35 percent.

We are searching for new second and third harmonic generators among the salts of organic acids and bases. We discuss the relevant properties of crystals from this group of compounds, including their nonlinear and phasematching characteristics, linear absorption, damage threshold and crystal growth. In addition, we summarize what is known concerning other nonlinear optical properties of these crystals, such as two-photon absorption, nonlinear refractive index, and stimulated Raman thresholds. A preliminary assessment is made of the potential of these materials for use in future high power, large aperture lasers such as those used for inertial confinement fusion experiments.

NH 4 ) 2 ZrF 6 , M-241.29, orthorhombic, Pca2 1 , a-13.398(8), b-7.739(3), c-11.680(4)A, V-1211.1 A 3 , Z-8, D-2.65 g/cm 3 , A(MoKa) -0.71073 A, ~-18.36 cm-1 , F(OOO)-928, T-296 K, R-0.026 for 6359 [F 2 >a(F 2 )] of 7225 total unique data.zr 2 F 12 units extend in an infinite chain along the £ axis.Each Zr has 8 fluorine neighbors with• distances ranging from 2.02 to 2.34 A.* Lists of structure factors, anisotropic thermal parameters, H-atom parameters

A novel injection and switchout scheme for multipass laser amplifiers is described. The method utilizes noncollinear difference frequency generation for injection and harmonic generation for switchout. Both injection and switchout are accomplished in the same crystal. The scheme is passive, avoids leakage through mirrors or electrooptic switching, and optically isolates the seed pulse generator fr...

L-arginine phosphate is a promising new material for generating harmonics of the Nd: YAG fundamental wavelength, 1064 nm. The synthesis of 20 other salts of L-arginine was attempted and millimeter size crystals of 10 of these were obtained. These were analyzed for crystal structure and chemical composition and the linear and nonlinear optical properties were measured. The compounds were all oprically biaxial and several gave second harmonic signals greater than quartz. Phasematching has been observed in four of the crystals to date.

High average power frequency conversion using solid-state nonlinear materials is discussed.Recent laboratory experience and new developments in design concepts show that current technology, a few tens of watts, may be extended by several orders of magnitude.For example, using KD*P, efficient doubling ( > 70 percent) of Nd:YAG at average powers approaching 100 KW is possible; for doubling to the blue or UV regions the average power may approach 1 MW.Configurations using segmented apertures permit essentially unlimited scaling of average power.High average power is achieved by configuring the nonlinear material as a set of thin plates with a large ratio of surface area to volume, and cooling the exposed surfaces with a flowing gas.The design and material fabrication of such a harmonic generator is well within current technology.

A technique for frequency conversion of high-power lasers is described which uses two crystals for each conversion step rather than one. The two crystals are oriented so that the waves generated in them are orthogonally polarized. The conversion efficiency of these quadrature arrangements is much less sensitive to laser pulse nonuniformities than that in single-crystal methods. Consequently, very ...

We consider all possible paths for amplified spontaneous emission (ASE) in multipass laser amplifiers using a Cassegrainian telescope geometry. In particular, we study ASE which is reflected back into the medium off the telescope mirrors themselves. These ASE components are unavoidable in this amplifier geometry. We show that there is a component of the ASE which makes approximately double the number of passes through the amplifier as the laser signal makes. We also show that these high order ASE components are also present in amplifiers which are almost Cassegrainian. They cannot be eliminated by changing the ratio of the scraper and hole radii or the separation of the mirrors. It is likely that these ASE components will be more significant in pulsed lasers than cw lasers.

The linear electrooptic effect is reviewed with emphasis on understanding the implications of crystal symmetry with regard to device performance. The index changes and the rotations of the index ellipsoid are calculated in detail for each of the 18 biaxial and uniaxial electrooptic crystal classes, and for an applied field of arbitrary direction. For most crystal classes, the EO effect exhibits orthogonality where the index changes and the ellipsoid rotation are proportional to orthogonal components of the applied field. Explicit expressions are given in each crystal class for the electrooptic parameters of selected attractive EO device configurations.

The average power of electrooptic switches is limited by thermal effects arising from linear optical absorption of the laser pulse. Under some circumstances, even a small optical absorption can cause the switch to be the average-power-limiting component of the laser system. These thermal effects can be managed by configuring the switch as a cooled thin plate. The thermal properties of thin plate s...

Measurements of the dispersion of the refractive index using a nonlinear interferometer are described. A sample of the optical material to be measured is interposed between two optically nonlinear crystals, and a moderately intense laser is passed through the combination. By observing the interference between the second harmonics produced in the two nonlinear crystals, the difference between the refractive indices of the sample at the laser frequency and its second harmonic frequency can be determined very precisely. We have used the interferometer to measure the dispersion in several gases between 1064 and 532 nm. We have also used it to determine the dispersion of two transparent solids. The method can measure the index difference to better than 0.1%, which for gases such as helium represents an absolute accuracy of ∼10−9.

The advantages of short wavelength (<1-μm) inertial fusion laser drivers have been known for sometime.1 The Nd:glass laser can provide this capability through the use of a well-known technique called harmonic generation.2 Recent small scale ICF experiments using this approach3-5 have indicated that significant improvement in target performance can be achieved at 0.532- and 0.355-μm wavelengths.