Tian Zhaoshuo

Kinetic modelling of electrooptically Q-switched CO2 laser

In this paper, a six-temperature model for CO2 lasers is used to describe the process of the dynamic emission in the electrooptically Q-switched laser. The dissociation of CO2 molecules, the electron excitation and the energy-transfer of vibrational levels and the rotational relaxation of rotational levels are involved. The calculated pulse waveforms are in good agreement with the experiment.

Theoretical and Experimental studies on CH3OH THz Laser Pumped by Pulse Carbon Dioxide Laser

In this paper, according to the molecular structure and vibration mode of micro-asymmetric gyroscope CH3OH molecule, dynamic process of optically pumped Terahertz laser is analyzed theoretically. The rate equation models based on three level systems are given according to the theory of typical laser rate equation. The output THz pulsed laser waveform is obtained by solving the rate equation model. An all-metal Terahertz laser pumped by RF waveguide carbon dioxide laser is designed with CH3OH as its working gas. The pulsed Terahertz laser output is obtained. The waveform and repetition frequency of the optically pumped laser are measured in the experiments. The Terahertz laser designed does not need water cooling system. It also has the advantages of simple structure and small size.

Photo-electrical properties of single Cu-TCNQ nanowire

In this letter, photo-electrical transport properties of individual Cu-TCNQ nanowire are studied. The electronic transport mechanism for single Cu-TCNQ nanowire well follows one-dimensional (1D) Motts model in the temperature range from 80 to 300 K. The Cu-TCNQ nanowire shows photoconductivity at visible illumination, with much faster response time than recovery time. The thermionic emission (TE) and thermionic-field emission (TFE) models are employed to interpret the current versus voltage (I–V) plots, by considering fitted results for the reversely biased contact barriers. Our present work opens up potential applications of single Cu-TCNQ nanowire in organic photo-electric nanodevice.

Double-vacuum sealed Z-fold dual-channel RF-excited CO 2 waveguide laser

RF-excited (Radio Frequency excited) waveguide CO2 laser with two channels has been widely applied in coherent detection, coherent laser radar, etc. In this paper a novel structure of Z-fold dual-channel RF-excited waveguide CO2 laser with double-shell vacuum was developed, which own the advantage of long operating life. The laser was composed of double-shell vacuum chamber. The pressure and the ratio of both vacuum chamber gas were equivalent. The waveguide structure was composed by a metal ceramic sandwich which was fixed into the first vacuum chamber. The second vacuum chambers were used to reduce the leak speed of the first vacuum chamber in order to maintain the pressure of the first vacuum chamber. In experiments, the life of the single vacuum laser is about 150 hours, and the double vacuum laser operating life is about 700 hours.

Research on optimal detecting position for one-dimensional scanning lidar

In laser radar imaging system, the target requires to be scanned in order to obtain total field of view (FOV) image and the movement of the scanner has influence on imaging. The limitation of detector panel caused echo signal from various directions cannot be obtained by receiver. In this paper, an optimal detecting position was simulated by ZEMAX software in one-dimensional bistatic imaging laser radar optical system with plane scanning mirror. Meanwhile, experiment confirmation was conducted by He-Ne laser and simulated results were consistent with experimental results.

Analysis of Brillouin LIDAR equation and maximum detection depth in ocean telemetry

Brillouin Light Detection and Ranging (LIDAR) in ocean telemetry can be used for remote sensing of sound velocity, temperature and salinity profiles in the ocean. It is one of the most promising technologies to survey the ocean rapidly, for its virtues of flexibility, efficiency and high accuracy. On the basis of the pulse transmission process of stimulated Brillouin scattering (SBS), a Brillouin LIDAR equation is obtained, and the relationships between maximum detection depth and output energy per pulse of laser and attenuation coefficient of light in seawater are analyzed. The results show that increasing output energy of laser can improve the maximum detection depth of LIDAR system to a certain extent, and increasing the attenuation coefficient will lead to rapidly decline the maximum detection depth.

Incoherent and coherent beam combination for master oscillator/power amplifier system with stimulated Brillouin scattering mirror

In this paper, we studied incoherent and coherent beam combining for the master oscillator/power amplifier (MOPA) system with stimulated Brillouin scattering (SBS) mirror. Optic field intensity distributions in the near and far field are numerically calculated for the two kinds of system. The results show that good beam quality in the far field could be obtained. It provides a theoretical basis for experimental research in the future.

Mathematical modelling of gain-switched RF-excited CO2 waveguide laser

The detailed mathematical models for the evolution of light pulses in RF-excited CO2 waveguide lasers are derived. Explicit expressions for the pulse characteristics in RF-excited CO2 waveguide lasers are obtained. The effects of losses and unsaturated gain on output power are calculated.