<title>National Ignition Facility frequency converter development</title>

Abstract

A preliminary error budget for the third harmonic converter for the National Ignition Facility (NIF) laser driver has been developed using a root-sum-square-accumulation of error sources. Such a budget sets an upper bound on the allowable magnitude of the various effects that reduce conversion efficiency. Development efforts on crystal mounting technology and crystal quality studies are discussed.

<title>Third-harmonic performance of the Beamlet prototype laser</title>

“…On the other hmtd, only a 50-prad shift in phase matching angle is rrceded to pmducc the same effect in the doubler. Furthermore, h'rmsrnission interfemgrmua of the duubler obtained with unpukwized light exhibit several fcaturca in the rcfmctive index with a pattern similar to that shown in Figma l(b) [14]. Aa part of the NIF frequency converter develop ment effort, a comprehensive set of testa is now undcnvay to evaluate crystal homogeneity and its impact on harmonic generation.…”

“…Test parameters were designed to simulate NIF conditions as closely as possible. The frequency converter used in the tests was of a two-crystal design identical to that adopted for the NIF, consisting of type-I doubling in 10.5 mm of KDP followed by type-II sum-frequency mixing in 9.5 mm of deuterated KDP (KD*P) [12][13][14]. The crystals were 37-cm prototypes of the 40-cm NIF crystals, finished to a surface roughness of< 20 Angstroms RMS prior to the tests to be consistent with NIF specifications for optical quality.…”

Wavefront Shaping by a Small-Aperture Deformable Mirror in the Front Stage for High-Power Laser Systems

“…The wavefront is directly related to the far-field distribution of the output laser that influences the focused intensity as well as the alignment of the beam path in a high-power laser system (like spatial filter) [13]. Additionally, in a frequency conversion module, the frequency conversion efficiency decreases sharply with the increase of the wavefront error [14,15], due to the angle matching of conversion cannot be achieved perfectly in the full aperture range. Therefore, it is necessary to control the wavefront in high-power laser systems, which can satisfy the basic requirements for laser transmission, focusing, and frequency conversion [16,17].…”