The Gyrotrons as Promising Radiation Sources for THz Sensing and Imaging

Abstract

The gyrotrons are powerful sources of coherent radiation that can operate in both pulsed and CW (continuous wave) regimes. Their recent advancement toward higher frequencies reached the terahertz (THz) region and opened the road to many new applications in the broad fields of high-power terahertz science and technologies. Among them are advanced spectroscopic techniques, most notably NMR-DNP (nuclear magnetic resonance with signal enhancement through dynamic nuclear polarization, ESR (electron spin resonance) spectroscopy, precise spectroscopy for measuring the HFS (hyperfine splitting) of positronium, etc. Other prominent applications include materials processing (e.g., thermal treatment as well as the sintering of advanced ceramics), remote detection of concealed radioactive materials, radars, and biological and medical research, just to name a few. Among prospective and emerging applications that utilize the gyrotrons as radiation sources are imaging and sensing for inspection and control in various technological processes (for example, food production, security, etc). In this paper, we overview the current status of the research in this field and show that the gyrotrons are promising radiation sources for THz sensing and imaging based on both the existent and anticipated novel techniques and methods.

A Versatile Illumination System for Real-Time Terahertz Imaging

“…Moreover, this adaptability allows terahertz imaging in different configurations for transmission and reflection, and for various object geometries via multiple imaging schemes like inline scanning (1D), multi-exposure imaging (2D) or tomography reconstruction (3D). Along with the effort to persistently increase the maximal radiation output power of emitters such as infrared QCL pumped molecular laser [ 40 ] or gyrotrons [ 41 ], we bring forward terahertz imaging as a powerful tool for non-destructive testing applications. Current work is targeting the transposition of this system to lower frequency domain to benefit from the higher material penetrability while keeping a suitable resolution.…”

Расчет эффективности удвоения частоты излучения субтерагерцового гиротрона за счет решеточной нелинейности в монокристаллической пластине InP

“…Альтернативный способ получения интенсивного ТГц излучения -умножение частоты суб-ТГц источников за счет генерации гармоник в нелинейных кристаллах. Источниками излучения накачки здесь могут служить мощные гиротроны суб-ТГц диапазона, которые в настоящее время находятся в стадии значительного прогресса [12,13]. В непрерывном режиме генерации достигнута мощность до 1 кВт на частоте 263 ГГц [14], разработаны непрерывные гиротроны с уровнем мощности в десятки [15,16] и даже сотни [17] Ватт на частотах ∼ 500 ГГц, в которых достигнута плавная перестройка частоты в полосе 1−2%, импульсные [18,19] и непрерывные [20] гиротроны, работающие на частотах > 1 ТГц, предложены методы селективного возбуждения высших циклотронных гармоник, что позволяет кратно увеличить частоту генерируемого излучения без увеличения рабочего магнитного поля [21][22][23].…”

Numerical Modeling of a Rectangular Hollow-Core Waveguide for the Detection of Fuel Adulteration in Terahertz Region

“…Therefore, PCFs have become an essential part of terahertz signal propagation. Besides, these waveguides had been proposed as sensors for different applications, like chemical sensing [31][32][33], biomedical sensing [34], cancer cell detection [35]. Based on the structure of the core, the PCFs can be broadly classified into three different categories: solid core PCF [36], porous core PCF [14,[37][38][39], and hollow-core PCF [26,40].…”