Phase modulator for generating millejoule-level, few-cycle laser pulses

Reference Number: K 08-11

Inventors: Chang, Zenghu; Wang, He; Wu, Yi

Owner: Kansas State University Research Foundation

USPTO Link:

Invention Summary

Significant effort has been devoted to reduce laser pulse duration while increasing the pulse energy for application in both industry and academic research. Our new technique can produce pulses with much higher energy than previous adaptive pulse compressors and has potential to achieve pulses with single-cycle duration. While the shortest recorded pulse (2.8 fs) does not have enough energy for practical application and high power lasers (30 fs) suffer from narrow bandwidth, by improving the throughput of an adaptive phase modulator and by applying it to a high power hollow-core fiber, we compressed laser pulses to ~5 fs at half-millijoule energy levels. As far as we know, this is the highest energy few-cycle pulse ever achieved by adaptive pulse compressors. The phase controllable, millijoule level few-cycle pulses are a new powerful tool for studying single attosecond pulse generation and performing coherent control in new parameter spaces.

Compared to the most widely used method of pulse compression by chirped mirrors, the adaptive phase modulator used in this invention has a larger bandwidth and high flexibility of phase control because it can be adjusted to cope with the day to day phase variations of the white-light pulses and to compensate the high order phase errors.

Fig. 1 demonstrates the pulse spectra after passing through hollow core fiber and the phase modulator. Fig. 2 shows the MIIPS traces from the different iterations and the final pulse duration. Fig. 3 shows the FROG result to confirm the pulse duration.

Advantages

• Ability to produce short-duration (5.1 fs), higher-energy (300 µJ) pulses with potential to achieve mono-cycle pulses.

• New Phase modulator design creates higher-energy throughput (50%), easier pulse compression and pulse shaping.

• Modified Multiphoton Intrapulse Interference Phase Scan (MIIPS) simplifies setup and can be used to check correctness of applied phase pattern

Applications

• Coherent control experiments using sub-5 fs pulses

• High field physics

• Biological imaging

• Micromachining