Direct Classic Route of Generating Mono-Color EM-Pulse with Attosecond-Level Duration

• Main Authors: Hai Lin, Chengpu Liu
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: Applied Sciences
• Subjects: attosecond; laser pulse; radiation source; attosecond duration; classic orbit
• Online Access: https://www.mdpi.com/2076-3417/9/3/362

Current conception of attosecond pulse is based on Fourier optics and refers to an electromagnetic pulse with a broad, homogeneous weight Fourier spectrum. Its preparation/generation is along an indirect route in which the output of commercial available <inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">&#956;</mi> </semantics> </math> </inline-formula>m-level wavelength laser is &#8220;processed&#8222; by elaborately designed optics medium allowing high-order harmonics effect to change its Fourier spectrum to be of a flat high-frequency tail. Such an indirect, quantum scheme is limited by its efficiency in high-order harmonics generation. For higher efficiency, other routes for the same goal, i.e., light pulse with an attosecond-level duration, deserve to be tried. The method proposed is a direct, classic scheme. It is to directly control the time duration of classic electrons doing acceleration/deceleration in a feasible, elaborately-designed driving DC fields configuration. The duration can be adjusted by initial electrons velocity, geometric dimension of driving field configuration. The maximum strength of a generated pulse is controlled by the number of electrons. The frequency of a generated pulse is controlled by initial electrons position in the configuration. The shortest duration of single pulse can be down to sub-attosecond-level according to currently available minimum geometric dimension of driving field and suitable gesture of electrons entering into the driving field configuration. This work displays a feasible, direct, classic route of achieving EM pulse with an attosecond-level duration. In particular, the pulse is mono-color, rather than a superposition of Fourier components with nearly-equal weight.