Study Of THz Radiation Generated Via Optical Difference Frequency Generation Based On Nonlinear Crystal

The terahertz region of the electromagnetic spectrum spans the frequency range between the mid-infrared and the millimeter/microwave. This region has not been exploited fully to date owing to the limited number of suitable radiation sources and detectors. The researches including THz radiation source, THz detector, THz transmission and application (THz spectrum, THz imaging, THz wireless communication etc.) have been recognized research field in the world. THz technology has provided an attractive chance for the creation of science, the development of national economy and national security. Some developed countries such as America and Japan are devoting plenty of human and material resources to the THz research. Fully expanding research on THz science and technology has been of important strategetic meaning for our country. Moreover the research on THz source is the most important aspect of all. Our research belongs to the generation of THz radiation by using photonics methods. We are dedicating ourselves to research on all-solid-state, compactable, room-temperature, tunable THz radiation system via nonlinear optics because it is the foundation of THz wave application. The methods of THz generation can be divided into electronics and photonics. We use nonlinear optical method to obtain THz wave which belongs to photonics including nonlinear optical difference frequency generation, THz wave parametric oscillator and Cherenkov radiation etc. The author introduced new radiation structure of PPLN-THz parametric oscillator in theory and obtained conclusions of THz radiation via difference frequency generation based on seeking and reading plenty of articles. Experimentally we demonstrated stable dual-wavelength output to the best of our knowledge it is the highest level.Innovations:In theory introduced the model of surface-emitted THz wave by difference frequency generation in slant-strip-type PPLN for the first time and made necessary analyses based on the modelIn theory introduced new radiation structure of PPLN-THz parametric oscillator and obtained conclusions of THz radiation via difference frequency generation for the first timeIn theory established a threshold model for simultaneous dual-wavelength laser and analyzed the effects of the crystal temperature distributions determined by the incident power on the thresholds of simultaneous dual-wavelength laserTo the best of our knowledge, the output of 5.12 W is the highest simultaneous dual-wavelength CW operation using the quasi-three-level transition at 946 nm and the four-level transition at 1064 nm of a Nd:YAG crystal end-pumped by an LD. Experimentally obtained end-pumped 1318.8 and 1338.2nm dual-wavelength laser with the highest output power in our research field...