In this paper, a kind of electrodeless millimeter diameter micro xenon lamp was developed. The micro xenon lamp was driven by inductive coupling. The experimental investigation of the discharge characteristics and laser pump performance of the developed micro xenon lamp have been carried out. The energy coupling efficiency of the drive scheme is between 22.4% and 24.2%. The fluorescent spectrum of micro xenon lamp is composed of line spectrum and continuous spectrum, which is well matched with Nd3+ absorption spectrum. Because of its small size and flexible layout, it is suitable to be used as the pump light source of fiber laser. The fluorescence radiation of fiber can be improved by using multiple micro xenon lamps. Four micro xenon lamps can improve the fluorescence radiation power by 80.5% compared with only one. The results indicate a complete set of micro xenon lamps can be applied in the field of fiber lasers.
The rectangular diffraction grating on single crystal diamond was fabricated with the wavelength of 10.6 μm. A novel method called bi-layer lift-off technology was used to form the hard mask. This approach simplified the patterning process of the thick Al film and made the deep etching on single crystal diamond achievable according to our requirement. The fabrication steps and the bi-layer lift-off technology are demonstrated in detail. We characterized the diamond grating and found that the angles of its sidewalls were almost vertical (within 3°), with a mean roughness of Ra = 3.01 nm on the bottom and 12.4 nm on the top.
As the laser pumping source, pulsed xenon flash lamp is widely used in high power laser amplifier system such as inertial confinement fusion projects. The radiation efficiency of pulsed xenon flash lamp is the crucial parameter. In our previous work, it has been proven that the pulsed xenon flash lamp with annular section has higher radiation efficiency as well as laser amplifier efficiency compared with traditional flash lamp. To further improve the characteristics of this kind annular section flash lamp, a multi-electrode system was proposed for annular section flash lamp in this paper. Experimental results shown that the discharge channels established more quickly and expended fast to whole lamp tube space. Also the distribution of the discharge plasma is more uniform. The novel multi-electrode xenon flash lamp has been investigated in the aspects of the electrical characteristics, the discharge plasma channel, radiation and neodymium doped glass fluorescence. Experimental results show that discharge and radiation characteristics of xenon flash lamp with multi-electrode structure are improved. The detail mechanisms of the improvements for the multi-electrode structure will be discussed in this paper.
Grating is an important optical element widely used in high power laser system which is required for higher diffraction efficiency and high laser damage threshold. Compared with the traditional grating materials, diamond has excellent optical transmission properties, high anti-damage threshold, high thermal conductivity etc. Diamond grating has wide application prospect in high power laser system. Based on rigorous couple wave analysis method (RCWA) diffraction characteristics of diamond gratings with different structures were simulated and optimized; Also the diffraction characteristics of between diamond gratings and fused silica gratings were compared and analyzed. The studies showed that the optimized diamond grating could obtain high diffraction efficiency more than 94% in wider bandwidth and the bulk of diamond grating would be much smaller than that of fused silica gratings.
The light out-coupling efficiency of top-emitting OLED devices with different micro-structures was investigated with the aid of software FDTD solutions. The micro-structures included surface grating, wavy shape and spherical micro lens respectively. The simulation results indicated that the micro-structure was helpful to improve the light out-coupling efficient of OLED. Further more a complex spherical crown surface micro-structure was designed. The light out-coupling efficient of top-emitting OLED with the complex spherical surface improved 14% compared that of the device with smooth surface and 6% compared with micro lens.
As one of the key elements of high-power laser systems, the pulse compression multilayer dielectric grating is required for broader band, higher diffraction efficiency and higher damage threshold. In this paper, the multilayer dielectric film and the multilayer dielectric gratings(MDG) were designed by eigen matrix and optimized with the help of generic algorithm and rigorous coupled wave method. The reflectivity was close to 100% and the bandwith were over 250nm, twice compared to the unoptimized film structure. The simulation software of standing wave field distribution within MDG was developed and the electric field of the MDG was calculated. And the key parameters which affected the electric field distribution were also studied.
The pulse compression multilayer dielectric grating (MDG) is one of the key elements of high-power laser systems. Mixed metal multilayer dielectric gratings(MMDG) with wider spectrum and higher diffraction efficiency are gradually becoming hot topic in chirped pulse compressor. In this paper, we studied the reflection and diffraction characteristics of pulse compression grating, i.e MMDG. First the thin-film structure, which would be applied to MMDG, was designed by combining characteristic matrix method and global optimization algorithm and the influence of the metal thickness and the number of layer film to reflectivity was also analyzed. Grating design software based on reflectivity vector theory (RCW)was developed to analyze the diffraction characteristic of MMDG. Combining generic algorithm and RCW, the optimization design of MMDG is studied. Comparing the diffraction efficiency of before and after optimization design, the highest diffraction efficiency is higher than 99% and bandwidth of MMDG is over 200nm, 50nm wider than that of MDG.
In this paper, we do some research on the interior period microstructure of transparent materials
induced by a femtosecond laser of 800-nm wavelength. By adopting a nonlinear propagation physical
model of femtosecond laser pulses and considering the spherical aberration effect(SA), we analyze the
influence of nonlinear effects such an self-focusing, GDV, MPA, plasma defocusing and interface
aberration on femtosecond laser propagation in transparent materials. Meantime, in the case with
nonlinear effects and interface aberration, we research the influence of fs laser power, pulse width,
numerical aperture and focusing depth on period microvoid. Simultaneously, compared with simulating
results in different focusing lens numerical aperture, we find that big numerical aperature and deep
focusing more easily produced period voids.
The broadband mid-IR grating is required in the infrared spectrophotometer to keep the instrument compact. In this paper the optimization design of a type of broadband grating is studied by the rigorous diffraction grating electromagnetic theory. As a differential vector method, the rigorous coupled wave analysis (RCWA) has been widely used for the analysis and the design of diffractive structures. In this paper, firstly, the diffraction efficiency properties of the traditional broadband dual-blaze grating were analyzed by RCWA. Then a simple structure grating with broadband spectrum can be obtained to the dual-blaze grating. It is interesting that the designed grating only had one blazed angle which is more easily to made compared to dual-blaze grating. The optimization grating structure parameters were given. According to our design example of broadband, mid-IR metal grating, the grating with grating period 10.0μm and blazed angle 22 degree can obtain more than 80% diffraction efficiency within the whole broadest spectrum 8~18μm. The optimization design result demonstrates this simple structure grating is with broadband spectrum and more easily to produce than the dual-blaze gratings.
DPL coupling system was researched in this paper. First, the mathematic model of 3D and 2D light transmission in
hollow duct was analyzed and compared. Then the 3D simulation software for all rays of the coupling system -lens duct
was developed. The influence of various structural parameters of the hollow lens duct to the energy and the beam
distribution were discussed with the help of developed software. The structural parameters such as the duct length, the
lens radius, the size of the input and output ends were researched and were optimized to get higher efficiency and better
beam distribution. Finally, the energy conversion efficiency and the beam spatial distribution of before and after
optimization were compared. The results showed that the efficiency and the distribution of energy were well improved
after the optimization.
In this paper the rigorous coupled wave analysis (RCWA) was used to analyze the grating diffraction efficiency
properties. First, the RCWA must to be improved to avoid instability when the grating period and grating groove depth
are relatively large especially for TM mode incident wave. Then the global optimization method-genetic algorithm was
used to optimize the grating profile to achieve high diffraction efficiency. Based on the improved RCWA the grating
optimal design software(GODS) was developed with the aid of the genetic algorithms (GA). The optimized structure
parameters of several typical grating profiles in arbitrary incident angle were given by GODS within short time once the
optimal control parameters were selected.
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