THz-field-induced modulation of intraband current in CdS

Area of Science:

• Nonlinear optics
• Condensed matter physics
• Quantum optics

Background:

• Centrosymmetric materials typically do not generate even-order harmonics.
• Strong fields can break symmetry and enable new nonlinear phenomena.
• Terahertz (THz) fields offer unique control over electron dynamics.

Purpose of the Study:

• To investigate the effect of a strong THz field on harmonic generation in cadmium sulfide.
• To explore the modulation of odd harmonics and generation of even harmonics by THz fields.
• To elucidate the underlying mechanisms using a semiclassical approach.

Main Methods:

• Applying a strong co-propagating THz pulse to a cadmium sulfide crystal.
• Using a mid-infrared ultrafast laser as the driver.
• Employing a semiclassical model to analyze intraband current dynamics.

Main Results:

• Observed modulation of high-order odd harmonic yields by the THz field.
• Demonstrated THz-induced even harmonic generation in a centrosymmetric material.
• Showed that THz fields modify intraband currents, altering harmonic generation.

Conclusions:

• A strong THz field is an effective tool for controlling nonperturbative light-matter interactions.
• THz-driven manipulation of intraband currents offers a pathway to control harmonic spectra.
• This work opens new avenues for lightwave electronics and attosecond science.