No abstract

No abstract

No abstract

A new radiative heater for high T c thin film growth Rev.The design and performance of a radiative substrate heater that operates under vacuum in a highly oxidizing environment is described. Using this heater, substrate temperatures exceeding 1050°C are readily achieved. These are the highest temperatures reported for a pulsed laser deposition ͑PLD͒ heater that operates in an oxidizing ambient. This heater was designed for the growth of oxide thin films by PLD, but the design concept is suitable for other vacuum deposition methods requiring high substrate temperatures to be achieved in an oxidizing environment. In addition to the high substrate temperatures achievable, the design described enables easy switching between on-axis PLD and off-axis PLD ͑allowing both sides of the wafer to be coated in the same growth͒ and allows the target-to-substrate distance to be easily adjusted from outside the chamber.

We demonstrate, for the first time, a single-shot, complete spatiotemporal measurement of pulses from a terawatt-scale, multi-stage-amplified, low repetition-rate laser source. The ultrashort pulse electric field, E(x,y,z,t), is spatiotemporally complex due to distortions that accrue from multiple chirped-pulse amplifiers, which requires a complete characterization. Meanwhile, the instability of the laser source introduces field profiles that vary significantly from pulse to pulse, which, together with the low repetition-rate (15 shots/hour), requires the use of a single-shot measurement technique. To accomplish the measurements, we used a wavelength-multiplexed, digital-holographic technique called Spatially and Temporally Resolved Intensity and Phase Evaluation Device: Full Information from a Single Hologram, specially tailored to measure picosecond pulses at a wavelength of about 1 μm. Specifically, individual pulses from the compact multipulse terawatt laser were measured, with up to 0.3 J per shot of energy and ∼2 ps pulse durations, at 1052 nm. With these measurements, we characterized several major spatiotemporal distortions that affect the peak intensity at the laser focus, as well as the pulse-shape instability on a shot-to-shot basis. Our technique allows detailed diagnosis of laser pulses (especially high-order spatiotemporal distortions) and provides straightforward four-dimensional animations of pulse propagation to a focus.