CEP-stable tunable THz-emission originating from laser-waveform-controlled sub-cycle plasma-electron bursts

Area of Science:

• Plasma Physics
• Quantum Optics
• Terahertz (THz) Science and Technology

Background:

• Terahertz (THz) emission is crucial for various scientific and technological applications.
• Controlling THz emission frequency traditionally presents significant challenges.
• Previous methods often lack tunability or require complex setups.

Purpose of the Study:

• To investigate tunable THz emission from plasma driven by incommensurate-frequency two-color laser fields.
• To develop and validate a semi-classical model for THz emission.
• To achieve continuous tuning of THz emission into the mid-infrared (mid-IR) spectral range.

Main Methods:

• A semi-classical transient electron current model was derived from quantum mechanical principles.
• Experimental generation of two-color laser pulses using a CEP-locked laser and optical parametric amplifier.
• Utilizing incommensurate laser frequencies to drive plasma and generate THz emission.

Main Results:

• Successfully generated CEP-stable THz emission with continuously tunable frequency.
• Demonstrated tunability into the mid-IR range by adjusting the incommensurate laser frequencies.
• Experimental results show strong agreement with the developed semi-classical transient electron current model.

Conclusions:

• The study establishes a novel method for tunable THz-emission generation in plasma.
• The semi-classical model accurately describes the observed THz emission characteristics.
• This work paves the way for advanced THz sources with controllable spectral properties.