Photoionization

When the pulse becomes strong, it is likely to ionize the gas, inducing special effects, such as photoionization-induced blueshift [1, 2]. It is important to take this effect into account in simulations, especially for strong pulses. Most previous work on gas-based nonlinear optics in hollow-core fibers are based on the Ammosov–Delone–Krainov (ADK) model due to its simple implementation [3-6]; however, the ADK model works the best only when the Keldysh parameter < 1/2 which is satisfied only by strong low-frequency fields. In our model, we implement the Perelomov-Popov-Terent’ev (PPT) model, which works for an arbitrary Keldysh parameter [7].

For more information, please see the supplement of our paper.

Photoionization-induced blueshift in He with different pulse energies from (a) our model and (b) Huang’s experiments [9].

[1] M. F. Saleh, W. Chang, P. Holzer, A. Nazarkin, J. C. Travers, N. Y. Joly, P. St. J. Russell, and F. Biancalana, “Theory of Photoionization-Induced Blueshift of Ultrashort Solitons in Gas-Filled Hollow-Core Photonic Crystal Fibers”, Phys. Rev. Lett. 107, 203902 (2011).

[2] Z. Y. Huang, Y. F. Chen, F. Yu, D. Wang, R. R. Zhao, Y. Zhao, S. F. Gao, Y. Y. Wang, P. Wang, M. Pang, and Y. X. Leng, “Continuously wavelengthtunable blueshifting soliton generated in gas-filled photonic crystal fibers”, Opt. Lett. 44, 1805–1808 (2019).

[3] P. A. Carpeggiani, G. Coccia, G. Fan, E. Kaksis, A. Pugzlys, A. Baltuska, R. Piccoli, Y.-G. Jeong, A. Rovere, R. Morandotti, L. Razzari, B. E. Schmidt, A. A. Voronin, and A. M. Zheltikov, “Extreme Raman red shift: ultrafast multimode nonlinear space-time dynamics, pulse compression, and broadly tunable frequency conversion”, Optica 7, 1349–1354 (2020).

[4] W. Chang, A. Nazarkin, J. C. Travers, J. Nold, P. Holzer, N. Y. Joly, and P. St. J. Russell, “Influence of ionization on ultrafast gas-based nonlinear fiber optics”, Opt. Express 19, 21018–21027 (2011).

[5] M. F. Saleh and F. Biancalana, “Ultra-broadband supercontinuum generation in gas-filled photonic-crystal fibers: the epsilon-near-zero regime”, Opt. Lett. 46, 1959–1962 (2021).

[6] J. C. Travers, W. Chang, J. Nold, N. Y. Joly, and P. St. J. Russell, “Ultrafast nonlinear optics in gas-filled hollow-core photonic crystal fibers [Invited]”, J. Opt. Soc. Am. B 28, A11–A26 (2011).

[7] A. M. Perelomov, V. S. Popov, and M. V. Terent’ev, “Ionization of Atoms in an Alternating Electric Field”, Sov. Phys. JETP 23, 924 (1966).

[8] Y.-H. Chen, J. Moses, F. Wise, “Femtosecond long-wave-infrared generation in hydrogen-filled hollow-core fiber”, J. Opt. Soc. Am. B (2023)

[9] Z. Y. Huang, Y. F. Chen, F. Yu, D. Wang, R. R. Zhao, Y. Zhao, S. F. Gao, Y. Y. Wang, P. Wang, M. Pang, and Y. X. Leng, “Continuously wavelengthtunable blueshifting soliton generated in gas-filled photonic crystal fibers”, Opt. Lett. 44, 1805–1808 (2019).