Abstract
Pulse contrast is a crucial parameter of high peak-power lasers since the prepulse noise may disturb laser–plasma interactions. Contrast measurement is thus a prerequisite to tackle the contrast challenge in high peak-power lasers. This paper presents the progress review of single-shot cross-correlator (SSCC) for real-time contrast characterization. We begin with the key technologies that enable an SSCC to simultaneously possess high dynamic range ($10^{10}$), large temporal window (50–70 ps) and high fidelity. We also summarize the instrumentation of SSCC prototypes and their applications on five sets of petawatt laser facilities in China. Finally, we discuss how to extend contrast measurements from time domain to spatiotemporal domain. Real-time and high-dynamic-range contrast measurements, provided by SSCC, can not only characterize various complex noises in high peak-power lasers but also guide the system optimization.
Highlights
High peak-power lasers open the door to strong-field physics such as plasma acceleration[1, 2]
The aim of pulse-contrast measurement is to reveal the noise background and prepulse spikes at the leading edge of the main pulse, and to judge whether it is below the ionization threshold of the target
Most current single-shot cross-correlator (SSCC) characterize laser pulses in the near-field, whereas targets are normally located in the far-field
Summary
High peak-power lasers open the door to strong-field physics such as plasma acceleration[1, 2]. For example, the pulse contrast should reach 1010 approximately Accurate measurement of such a high contrast is the prerequisite to explore unknown noise mechanisms and optimize the laser systems. It is extremely inefficient for the DSCC to measure the petawatt lasers operating at a low repetition rate ( 10 Hz) or even single shot[2,3,4, 12, 13] This determines that the DSCC could hardly be applied for the real-time optimization of laser systems, and is only suitable to evaluate the contrast parameter after construction. The artificial noise during measurement can be as large as 10−6–10−8 of the main pulse, which will severely degrade the measurement fidelity[24] This fidelity issue, has not drawn attention due to the limited dynamic range of SSCC. We discuss the prospect of extending the SSCC to spatiotemporal crosscorrelator (STCC) and summarize the review
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