Toward high-power terahertz radiation sources based on ultrafast lasers

Abstract

The development of new photon sources has propelled scientific and technological breakthroughs across disciplines, ranging from atomic physics and quantum technology to optoelectronics, chemistry, and biomedical devices. This is particularly evident with emerging photon sources of previously unattainable high power, allowing for the clear deconvolution of semiconductor energy states and the elucidation of the dynamics of quasi-particles and molecular vibrations. Terahertz (THz) radiation, once considered a gap in the electromagnetic spectrum, has become readily accessible with advancements in ultrafast optics. While various sources and detectors are available, their output intensity based on typical femtosecond lasers remains still limited to approximately 0.5 mW at 1 THz, constraining their widespread applications. In this review, we explore the main mechanisms and recent advancements in THz radiation generation using nonlinear optics, optoelectronics, and plasma. We summarize their characteristics by examining their performance across different optical configurations. Additionally, we review a novel approach utilizing acoustic waves, initially proposed approximately 15 years ago, but only limited subsequent progress has been made. We delineate the challenges associated with this approach and propose potential solutions, highlighting the significance of further investigation and improvement, which could potentially catalyze a breakthrough in this field.