Simultaneously measuring absolute and relative delay of laser pulses

Recently, researchers from the Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) have made new progress in the timing measurement and control of ultrashort laser pulses.

The researchers proposed to use the double-hump laser spectrum to obtain a near-field interference pattern, which could simultaneously measure the absolute and relative delay of the laser pulses. The time jitter was compensated by a feedback loop. The results were published in Optics Express on November 10, 2020.

Owing to the advantages of high precision, fast response speed and high signal-to-noise ratio, laser synchronization technology has been used in precision synchronization and control in various fields, such as optical parametric amplification, laser coherent beam combination, and coherent synthesis. The previous technologies can measure the relative delay between laser pulses but are not able to measure the absolute delay accurately.

In this study, the researchers used the double-hump spectrum to obtain the near-field interference pattern of two beams. The absolute delay between laser pulses was accurately measured by the effective recognition of the interference pattern envelope, and the time jitter was controlled by a closed-loop feedback system. A sub-femtosecond synchronization accuracy was achieved.

The proposed scheme avoids the influence of absolute delay in the applications of laser synchronization and coherent synthesis and reaches higher synchronization accuracy and peak intensity.

This study has developed a new way of measuring and controlling the absolute delay of laser pulses, that provides a solution for related applications.