Acta Photonica Sinica, Volume. 52, Issue 6, 0614002(2023)

Theoretical Study of Near Single-cycle Post Compression for Yb Dopped Lasers

Qi CHENG1,2, Hao YUAN1,2, Huabao CAO1、*, and Yuxi FU1、**
Author Affiliations
  • 1Center for Attosecond Science and Technology, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
  • show less

    The attosecond light source can reveal the macroscopic properties of matter from the microscopic field, so it is widely used in the fields of materials, medicine, atomic and molecular physics, and quantum physics. The common laser for generating attosecond light sources is the Ti∶Sapphire laser with a central wavelength of 800 nm. However, the average power is limited due to the thermal effect limitation. With the deepening of the application of attosecond light sources, high power with a high repetition rate driving laser if highly demanded. In order to achieve the driving laser with short pulse duration, high repetition rate and high pulse energy, Yb-doped lasers, such as Yb∶KGW, Yb∶YAG have been developed rapidly in recent years. However, the pulse duration of the Yb-doped laser is much longer, and it needs to be compressed by a post-compression method in order to obtain few-cycle laser pulses. Noble gas filled hollow core fibers are widely employed for pulse compression, but it is difficult to compress the 515 nm pulses obtained by frequency doubling to a nearly single cycle. Therefore, this paper simulates the compression obtaining few cycle pulses based on the time-domain generalized nonlinear Schr?dinger equation satisfied when the pulses are transmitted in a hollow core fiber. The light source in the calculation process refers to the PH2-2mJ-SP laser of Light Conversion Company, the center wavelength is 1 030 nm, the repetition rate is 10 kHz, and the pulse energy is 2mJ. In the simulation, the input pulse with a center wavelength of 515 nm, a pulse energy of 1 mJ, and a pulse duration of 250 fs is employed, which peak power is 4×109 W. In order to achieve controlled spectral broadening with minimum loss in the hollow core fiber, the peak power of the pulse should first be less than the photoionization threshold intensity of the noble gas, which limits the minimum core radius to 50 μm. Besides, the peak power should be lower than the self-focusing threshold in order to avoid self-focusing when the pulse is transmitted in a hollow core fiber, which limits the maximum pressure of the noble gas. For the argon and krypton to be investigated, the maximum pressures are 10 bar and 3.5 bar, respectively. Considering the loss coefficient when the pulse is transmitted in the hollow core fiber, and the broadening factor required to broaden the pulse spectrum to an octave, a preliminary length of 2.5 m and a core radius of 125 um can be determined for the hollow core fiber. On this basis, the frequency spectrum and time domain broadening of the pulses under various gas pressure and propagation length are simulated. Finally, the pulse spectrum can be broadened to an octave. Considering the influence of the broadening factor and transmission efficiency, the length of the hollow core fiber is finally selected as 2.5 m when the argon and krypton are filled at their maximum pressures. After compensating the dispersions, the pulses of 2.91 fs and 2.62 fs can be obtained in argon and krypton, respectively, which are less than two optical cycles. But at this time, the compressed pulses still have some high-order dispersion that cannot be compensated. Thus, we employed the multi-stage compression method, which avoids introducing too much high-order dispersion. The first stage compression is referenced to the work of HARITON V et al., who successfully compressed a 515 nm, 250 fs pulse to 38 fs in their experiments using a multi-pass cavity. The second stage uses a hollow core fiber. Under the appropriate gas pressure, transmission length, and dispersion compensation, the pulse is compressed to ~ 2 fs, which is close to a single cycle, with significantly reduced high-order dispersion than that from single stage compression.

    Tools

    Get Citation

    Copy Citation Text

    Qi CHENG, Hao YUAN, Huabao CAO, Yuxi FU. Theoretical Study of Near Single-cycle Post Compression for Yb Dopped Lasers[J]. Acta Photonica Sinica, 2023, 52(6): 0614002

    Download Citation

    EndNote(RIS)BibTexPlain Text
    Save article for my favorites
    Paper Information

    Category:

    Received: Mar. 1, 2023

    Accepted: Mar. 28, 2023

    Published Online: Jul. 27, 2023

    The Author Email: CAO Huabao (caohuabao@opt.ac.cn), FU Yuxi (fuyuxi@opt.ac.cn)

    DOI:10.3788/gzxb20235206.0614002

    Topics