Donald J. Gettemy

Some optical properties of KTP, LiIO/sub 3/, and LiNbO/sub 3/

Measurements of the absorption coefficient for KTP, LiIO/sub 3/, and LiNbO/sub 3/ are discussed. The variation of the refractive index with temperature has been measured for KTP and LiIO/sub 3/. It is necessary to know both the absorption coefficient beta and the variation in the indexes of refraction with temperature change dn/dT to determine the average power limit of a nonlinear interaction. With the dn/dT information, it is also possible to estimate the temperature half width of any nonlinear interaction by calculating the variation of the phase-matching condition with temperature. >

Variation of the refractive index with temperature and the tuning rate for KDP isomorphs

The variation of refractive index with temperature is measured as a function of wavelength, temperature, and polarization for KDP and eight of its isomorphs. These data are used to predict the tuning rate for second-harmonic generation as a function of temperature. The predicted tuning rate compares well with the measured tuning rate. Reasonable agreement is found in most cases, the principal exceptions being those cases in which the data must be extrapolated significantly beyond the range of the measured values.

Comparison of Nd 1.06 and 1.33 µm operation in various hosts

Performances of Nd in various hosts including Nd:YAG, Nd:YLF, Nd:BEL, and Nd:Cr:GSGG were characterized and compared for operation on the nominal 1.06 μm and 1.33 μm transitions. Comparison included continuous mode operation, normal mode operation, Q -switched operation, and gain measurements. Continuous lasing of Nd:Cr:GSGG under lamp pumping is reported for what may be the first time. Characterization included operation with different mirror reflectivities to obtain the internal losses, measurement of the upper laser level lifetime, measurement of the beam quality of the lasers operating under nominally similar circumstances, and measurement of the wavelength. These measurements should provide a comparison of the various Nd hosts under similar circumstances for a wide variety of operational modes and at both wavelengths of interest.

Temperature variation of the refractive indices of yttrium lithium fluoride

The temperature variations of the refractive indices of LiYF4, YLF, have been measured in the visible region of the spectrum. The temperature variation at 0.546 μm are −0.67×10−6/°C and −2.30×10−6/°C for the ordinary and extraordinary refractive indices, respectively. A Sellmeier equation was fit to more extensive room-temperature refractive-index data measured elsewhere.

Performance of Ho:YAG as a function of temperature

The performance of two multiply doped Ho:YAG lasers has been characterized as a function of the laser rod temperature. From the experimental results, the dependence of the slope efficiency and threshold on temperature has been extracted. Threshold can be correlated with the occupation of the lower laser level. Implications on the optimum operating temperature are discussed.

Thulium YAG laser operation at 2.01 μm

Variable temperature laser experiments were performed with two compositions of Tm:Cr:YAG (5.0:1.0 and 1.5:2.0 percent substitutions), with special attention given to the spectroscopic details of energy transfer and quasi-3 level lasing. Differences in laser threshold and flashlamp degradation were found in lasing the two compositions, and it is suggested that the difference is due to the 1.5:2.0 rod having much less efficient energy transfer than the 5.0:1.0 Tm:Cr crystals. To first order, the thermal occupation factor is found to dominate laser threshold determination at temperatures betwen 120 and 240 K.

TEM 00 Mode Ho:YLF Laser

A flashlamp pumped liquid nitrogen cooled Ho:YLF laser was constructed and operated both normal mode and Q-switched. In normal mode operation, the laser produced over 300 mj at 2.9 percent slope efficiency but it operated on several lines. Lasing was restricted to one line and Q-switched operation was achieved up to 150 mj.

Cr:YSAG — A Tunable Near-Infrared Laser Material

Cr:YSAG has been evaluated as a tunable laser material in the near-infrared region of the spectrum. Basic parameters such as the upper laser level lifetime and the fluorescent spectra have been measured. Gain, as a function of flashlamp energy and wavelength, has also been measured.as well as the flashlamp-induced loss at 0.532 and 1.064 µm.

Thermal Cycling Absorption Process (TCAP): Instrument and Simulation Development Status at Los Alamos National Laboratory

The Thermal Cycling Absorption Process (TCAP) Project at Los Alamos National Laboratory has been a collaborative effort with Savannah River Site to demonstrate the Tube-in-Tube (TnT) column design and to improve TCAP science. TnT TCAP is an alternative design which uses a liquid to thermally cycle the metal hydride packed column. Inert gas displacement tests and deuterium pulse tests have been performed on the TnT TCAP column. The inert gas displacement tests are designed to measure plug flow in the column while the deuterium pulse tests determine the separation ability of the column. A residual gas analyzer measures the gases in the exit stream and the experimental results are compared with pulse test model results.

Performance of Ho:Tm:Cr:YAG and Ho:Tm:Er:YAG as a Function of Temperature

Concentration of the active atom as well as type and concentration of sensitizers can have a significant impact on the performance of a multiply doped Ho:YAG laser. Moreover, the temperature dependent performance depends on the concentrations of the various constituents of the laser rod. Performance of three laser rods, two sensitized with Tm and Cr and the third sensitized with Tm and Er, was measured as a function of temperature. Measured threshold correlates well with temperature dependent occupation factors while slope efficiency data correlates well with an up conversion process.