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A compact end-pumped Electro-optical Q-switched Nd:YAG laser was designed in this paper. In order to achieve compact construction, laser diode arrays(LDAs) with collimated fast axes were used as pumping source. A spherical lens with a focal length of 40 mm and a cylinder lens with focal length of 25 mm were used as a group for the coupling lens. The LDAs' beam profiles on the incident and exit faces were calculated using Tracepro software. The simulation results indicate that when taking a Φ 6 mm×30 mm Nd:YAG with a doping concentration of 1.0at.% as the gain medium, the spots on the incident and exit faces were 5 mm(slow-axis)×4.5 mm(fast-axis) and 3 mm(slow-axis)×6 mm(fast-axis), respectively, and the absorption pumping power was about 83%. Dynamic temperature field distributions of Nd:YAG larer in 360 s at 22℃ and 60℃ were simulated by Ansys software. Output pulsed energy of 30 mJ and 25 mJ were achieved while the repetition frequencies were 30 Hz and 50 Hz, corresponding to a slope efficiency of 11.6% and 14.71%. The pulse durations were 18 ns and 16 ns, respectively. The experimental results show that the designed compact laser in this paper can achieve stable pulse laser output.

Nonlinear optical switch based on two-dimensional material is the core device of Q-switched fiber laser. The concentration of two-dimensional material optical switch will directly affect its nonlinear optical absorption characteristics, thus changing the time-domain characteristics of the pulse. Therefore, the influence of two-dimensional material concentration on Q-switched optical pulse is studied, and a saturable absorption optical switch based on Ti: Bi2Te3 with different concentration is made through experiments. The influence of Ti: Bi2Te3 concentration on nonlinear optical absorption characteristics is analyzed, and the relationship between the modulation depth, pulse width, repetition frequency and single pulse energy of Q-switched optical pulse with different concentration Bi2Te3 is obtained. Finally, the Ti: Bi2Te3 concentration is optimized for the resonator parameters. When the pump power is 71 MW, the central wavelength is 1560 nm, the pulse width is 8 μ s, the repetition frequency is 14.2 kHz, the average output power is 2.15 MW, and the corresponding single pulse energy is 151.4 NJ.

The luminance and chromaticity of monitors are measured through color luminance meters.Small-field optical filter color luminance meter is widely used in production line for its low-cost.Image color luminance meter,as a new product,is also a kind of optical filter color luminance meters.But it is large-field because of the different detector.Its structure,principle and performance are also different.Making performance contrast between these two kinds of optical filter color luminance meters helps estimating the image color luminance meter's quality.This paper makes a performance contrast between the two kinds' representative through principle analysis and experiment.It turns out that the performance of the image color luminance meter is no worse than the small-field optical filter color luminance meter.

To overcome the disadvantage of low radiation power for photoconductive antenna,three types of antennas,including dipole,bow-tie and spiral antennas,are studied,where finite integration technology are used to compute their radiation impedances.The simulation results show that the impedance of dipole antenna is dependent on the dipole length,width,photoconductive gap and the width of transmission line,and has a peak value in resonant frequency,so the dipole antenna is suitable for applications working at specific terahertz frequency.The bow-tie and spiral antennas,known as broadband antennas,have approximately stable impedance over the terahertz frequency range under study.The simulation results also show that,the interdigitated fingers,which can be modelled as an additional capacitance,cause the antenna impedance to fall dramatically at high frequency.