In this paper, characterizations of a cryogenic Xe capillary jet target for a laser-produced plasma extreme ultraviolet (EUV) light source are reported. The capillary jet target is a candidate of fast-supplying targets for mitigating debris generation and target consumption in a vacuum chamber without reducing the EUV conversion efficiency. Xe capillary jets (jet velocity ~ 0.4 m/s) were generated in vacuum by using annular nozzles chilled to ~ 170 K at a Xe backing pressure of ~ 0.7 MPa. Forming mechanisms of the capillary jet targets were studied by using numerical calculations. Furthermore, laser-produced plasma EUV generation was performed by irradiating a Nd:YAG laser (1064 nm, ~ 0.5 J, 10 ns, 120 μmφ, ~ 4×10<sup>11</sup> W/cm<sup>2</sup>) on a Xe capillary jet target (outer / inner diameter = 100 / 70 μmφ). The angular distribution of EUV generation was approximately uniform around the Xe capillary jet target, and the peak kinetic energy of the fast-ions was evaluated to be ~ 2 keV.
We intended to use deposition-free target such as cryogenic Xe target as a laser produced plasma EUV source. We reported an enhancement of conversion efficiency (CE) by double pulse irradiation and a CE dependence on wavelength of drive laser. Lithium target used with hot multi-layer mirror was proposed by Cymer, as a new deposition-free target. We made EUV source studies experimentally on cryogenic Xe target and lithium new scheme target. In this paper, we report newly made double pulse irradiation experiments on cryogenic Xe target and an enhanced EUV generation with new "forced recombination" and/or "expansion energy re-conversion" lithium target. Laser systems used in the experiments were a 320 Hz repetition rate Nd:YAG slab laser and a 10 Hz Nd:YAG rod laser with maximum pulse energy of 1J. EUV emissions were measured by a time resolved and a time integrated imaging cameras, a transmission and a grazing incidence spectrometers, fast EUV photo-diodes and a Flying Circus 3 for power monitor. Temporal resolved EUV images from Li target indicate relatively long emission time and large emission area. The size of emission area is improved and the emission intensity is enhanced by adding a wall in front of the Li target. Experimental results indicate the expected forced recombination and expansion energy re-conversion characteristics.
Characteristics of large fan-out interconnection are studied in terms of signal propagation delay and power consumption. Four types of interconnection models are considered and their properties are formulated. The obtained result supports the effectiveness of optical digital computing schemes based on large fan-out interconnection such as optical array logic.
Bulk laser damage in CsLiB<SUB>6</SUB>O<SUB>10</SUB> was measured using a single-shot Q-switched Nd:YAG laser in a transverse and longitudinal single model. The bulk laser damage thresholds of CLBO, with laser irradiation direction (parallel) < 001 > and polarization (parallel) < 001 >, were determined to be 29 GW/cm<SUP>2</SUP> at 1.064 micrometers , and 6.4 GW/cm<SUP>2</SUP> at 0.266 micrometers . The value at 1.064 micrometers is higher than that of fused quartz, (beta) - BaB<SUB>2</SUB>O<SUB>4</SUB> and KH<SUB>2</SUB>PO<SUB>4</SUB>. The morphology of bulk damage in CLBO crystal was also observed. THe damage pattern suggests that the < 001 > direction is mechanically weak, which is consistent with the result of the mechanical strength tests.
This paper investigates ion etching process to the surface of CsLiB<SUB>6</SUB>O<SUB>10</SUB> (CLBO) crystal. Laser-induced surface damage was reduced and surface durability of CLBO crystal was improved by removing the subsurface embedded polishing compound. There was no surface degradation as a result of the ion etching. The effects of ion etching on surface damage were measured by a 1-on-1 test at a laser wavelength of 266 nm. Durability of the CLBO crystal was tested by the approximately 7 W fourth harmonic generated by a Nd:YAG laser. The durability of the ion etched surface was improved more than 10 times as compared with the as-polished surface.