共查询到20条相似文献,搜索用时 15 毫秒
1.
Yang Liao Bin Zeng Lingling Qiao Lianqing Liu Koji Sugioka Ya Cheng 《Applied Physics A: Materials Science & Processing》2014,114(1):223-230
Recently, femtosecond laser direct writing in porous glass is emerging as a powerful technique for building arbitrary 3D hollow micro/nanostructures in bulk glass materials. In this study, we investigate the pulse duration dependence of laser intensity window for inducing a single nanocrack inside porous glass by femtosecond laser direct writing. We find that the window for a single nanocrack increases with the pulse duration, while the roughness of side walls in the nanocracks becomes higher for pulses longer than ~300 fs. When the femtosecond laser pulses of an optimized duration of ~200 fs are chosen, a sufficiently broad range of laser intensity (~44 % of the structuring threshold) for creating a single nanocrack can be obtained, while smooth sidewalls required by nanofluidic applications can still be maintained. The reported results will be beneficial not only for the development of the 3D femtosecond laser micro/nanostructuring techniques, but also for gaining a deeper understanding of the physical mechanism behind the nanograting formation induced by femtosecond laser irradiation in glass and other transparent materials. 相似文献
2.
Sung-Hak Cho Won-Seok Chang Kwang-Ryul Kim Jong Wook Hong 《Optics and Lasers in Engineering》2009,47(1):127-132
Time-resolved dynamics of plasma formation and bulk refractive-index modification in fluoride glass (ZBLAN) excited by a tightly focused femtosecond (130 fs) Ti:sapphire laser (λp=790 nm) was observed in situ. The femtosecond time-resolved pump–probe measurement with perpendicularly linear polarized beams was used to study the dynamics of both plasma formation and induced permanent structural transformation with refractive-index change. In the refractive-index domain, the lifetime of induced plasma formation is ~35 ps and structural transition time for forming the refractive-index change is ~80 ps. In the optical damage domain, however, the lifetime of induced plasma formation is ~40 ps and structural transition time for forming the optical damage is ~140 ps. We found that the process of refractive-index bulk modification is significantly different from that of optical cracks. From the diffraction efficiency of Kogelnik's coupled mode theory, the maximum value of refractive-index change (Δn) was estimated to be 1.3×10?2. By the scanning of fluoride glass on the optical X–Y–Z stages, the fabrication of internal grating with refractive-index modification was demonstrated in fluoride glass using tightly focused femtosecond laser. 相似文献
3.
利用有限元法对脉冲CO2激光辐照K9玻璃样品中的温度和应力分布进行了数值分析。对半径为20mm、厚为2mm的圆盘样品的计算结果表明,K9玻璃的损伤由环向应力控制,体损伤先于面损伤产生,且光斑半径和脉冲数目对损伤闽值有较大的影响,在激光光斑半径为5mm,脉宽为10肛s的条件下K9玻璃的单脉冲CO2激光的损伤闽值为0.5J,相应的能量密度为0.637 J/cm^2。损伤闽值随光斑半径的增大而增大,随脉冲数目的增加而变小。讨论了样品半径和厚度对损伤结果的影响,结果表明样品半径在10-20mm范围内所产生的拉伸应力较小。 相似文献
4.
In situ observation of photoinduced refractive-index changes in filaments formed in glasses by femtosecond laser pulses 总被引:5,自引:0,他引:5
We investigated the relationship between the formation of filaments and local refractive-index changes induced by femtosecond laser pulses in silica glass. In situ observation revealed that the location of a filament coincided with that of the refractive-index change. Observation also showed that the region of refractive-index change was elongated toward the upstream direction of the laser pulses with increasing exposure time. The region of refractive-index change was several hundred micrometers long, and its diameter was smaller than 2 mum. The refractive-index change was confirmed by two of three different methods to be as large as 0.8 x 10(-2). 相似文献
5.
Cheng Y Sugioka K Midorikawa K Masuda M Toyoda K Kawachi M Shihoyama K 《Optics letters》2003,28(1):55-57
Theoretical and experimental investigations have been made of the three-dimensional microchannel fabrication of photostructurable glass by use of a femtosecond (fs) laser. Generally, a microchannel fabricated inside glass by the scanning focal spot of a fs laser perpendicular to the direction of laser propagation assumes an elliptical shape with a cross section of large aspect ratio. We demonstrate that one can greatly reduce the aspect ratio merely by inserting a slit, which is oriented parallel to the laser's scanning direction, before the focusing lens. Computer simulations show that a more symmetrical pattern is obtained in the vicinity of the focal point with the help of such a slit, owing essentially to a diffraction effect. 相似文献
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8.
We presented a microfabrication process for optical volume vortex grating inside glass by femtosecond laser pulses. The self-trapped filament of femtosecond laser pulses can induce hundreds μm-long region refractive-index changes in glass. We realized the restructured optical vortex beams using a collimated He–Ne laser beam. The maximum first-order diffraction efficiency was about 19.6%. The volume vortex grating structure fabricated in glass is polarization dependent. 相似文献
9.
S.-H. Cho H. Kumagai K. Midorikawa 《Applied Physics A: Materials Science & Processing》2003,76(5):755-761
The time-resolved dynamics of plasma self-channeling and refractive index bulk modification in silica glasses were first observed
in situ using a high-intensity femtosecond (110 fs) Ti:sapphire laser (λp=790 nm). Plasma channeling is induced in silica glass at an irradiation higher than an input intensity of 1.5×1012 W/cm2 and photoinduces either the refractive-index modification or optical crack modification. In the domain of refractive-index
modification, the lifetime of induced plasma self-channeling was 20 ps and the structural transition time for forming the
refractive-index change was 10 ps. In the domain of optical cracks, however, the lifetime of induced plasma formation was
30 ps and the structural transition time for forming the optical cracks was 40 ps. According to electron spin resonance spectroscopic
(ESP) measurement, it was found that the defect concentration of the SiE′ center increased significantly in the refractive index modification region. A maximum value of the refractive-index change
Δn was measured to be 1.6×10-2. The intensity profile of the output beam transmitted through the refractive-index modification showed that the bulk modification
produced a permanent optical waveguide.
Received: 8 April 2002 / Accepted: 12 April 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +81-48/462-4682, E-mail: shcho@riken.go.jp 相似文献
10.
Farid Ahmed Man Seop Lee Hitoshi Sekita Tetsumi Sumiyoshi Masanao Kamata 《Applied Physics A: Materials Science & Processing》2008,93(1):189-192
We propose an idea of fast cutting a display glass plate where the sample is pre-processed micromachining single shot rear-surface
and internal void arrays aligned on working plane prior to glass cleaving. Single shot void morphology is investigated varying
input pulse energy, focusing depth, and scanning speed. A femtosecond laser with pulse duration of 172 fs, central wavelength
of 780 nm, and repetition rate of 1 kHz is used to fabricate voids. 相似文献
11.
Y. Hanada K. Sugioka K. Midorikawa 《Applied Physics A: Materials Science & Processing》2008,90(4):603-607
We report the selective metallization of photostructurable glass by femtosecond (fs) laser direct writing followed by electroless
copper (Cu) plating. It was found that a Cu thin film can be deposited only on the rough surface of glass ablated by the fs
laser. The deposited Cu thin film exhibits strong adhesion and excellent electrical properties. A Cu film can even be deposited
on the internal wall of a hollow microchannel inside photostructurable glass by the multiphoton absorption of the fs laser.
To show the use of this technique for micro-total-analysis-system (μ-TAS) applications, the fabrication of a microheater operating
at temperatures up to 200 °C was demonstrated.
PACS 81.05.Kf; 85.40.Ls; 87.85.Va 相似文献
12.
M.H. Hong B. Luk’yanchuk S.M. Huang T.S. Ong L.H. Van T.C. Chong 《Applied Physics A: Materials Science & Processing》2004,79(4-6):791-794
A femtosecond (fs) laser application for multi-layer optical recording is investigated. Information patterns at different layer depths were written inside a transparent glass substrate due to micro-void formation by fs laser ablation, which causes re-distribution in glass materials and a refractive index modification. The information bits recorded in a single layer can be retrieved clearly without interference from the neighboring layers. A fs laser irradiation of a transparent polymer matrix (doped with fluorescent materials for use as low-cost recording media) is also studied. A fs laser induced photo-chemical reaction changes the chemical properties of the fluorescent materials and records information bits inside the matrix. With an ultra-fast laser as a new light source, 3D optical recording can be available for high capacity data storage up to 1 TB per disc. PACS 82.50.-m; 42.65. Re; 72.70.Jk. 相似文献
13.
A. V. Konyashchenko L. L. Losev V. S. Pazyuk S. Y. Tenyakov 《Applied physics. B, Lasers and optics》2008,93(2-3):455-461
The technique of Raman conversion of sub-100 fs laser pulses based on excitation of active medium by two orthogonally polarized pulses has been developed for Raman lasers with a glass capillary. 52 fs Stokes pulse at the wavelength of 1200 nm has been generated by stimulated Raman scattering of 48 fs Ti:sapphire laser pulse at the wavelength of 800 nm in hydrogen. 13% energy conversion efficiency has been achieved at pulse repetition rate up to 2 kHz. 相似文献
14.
Diffraction of white-light supercontinuum by femtosecond laser-induced transient grating in carbon bisulfide 下载免费PDF全文
Experiments on fs laser-induced transient grating (LITG) in carbon bisulfide (CS2 ) are carried out to explore the chirp characteristics of a white-light supercontinuum (SC) generated by a 800-nm, 160-fs laser pulse in a 4-mm thick Al2O3 crystal. Two orders of diffraction signals of SC by fs LITG in CS2 are observed, demonstrating that both the third-order process and the fifth-order process are present simultaneously. The experimental results also imply that the formation of an fs transient refractive-index grating in CS2 is mainly due to the electronic polarization process. 相似文献
15.
利用氧化钕和盐酸为原料制得Nd(phen)2Cl3(三氯二邻菲罗啉合钕),测得其光谱特性并以稀土氧化钕、苯甲酸和邻菲罗啉为原料制得绿色液体激光介质钕离子的配合物——NdB3phen(三苯甲酸—邻菲罗啉合钕).利用飞秒激光器,采用单光束Z-扫描法研究了NdB3phen的三阶非线性光学特性.结果表明:当入射飞秒激光脉冲波长为400 nm,峰值功率密度为2.94×1014 W/m2,脉宽为117 fs时,测得样品NdB3phen的非线性折射率为-2.84×10-18 cm2/W|NdB3phen在开孔条件下呈现反饱和吸收现象,测出双光子吸收系数的值为9.11×10-12 m/W.实验结果表明,NdB3phen的双光子吸收系数和非线性折射率随着光强的增强而增大. 相似文献
16.
实验研究了正色散固体介质中的激光脉冲自压缩现象,证明了无需任何外加色散补偿情况下,固体透明介质中的自聚焦传输过程可使高功率飞秒激光脉冲实现时域脉冲压缩,并详细研究了输出脉冲的时域和频域特性随入射脉冲强度的演化规律.实验结果表明脉冲自压缩量随入射脉冲强度的增加呈递增趋势,然而当入射光强增大到足以引起超连续谱及锥形辐射产生时,脉冲时域形状会发生分裂.此外还发现发散光束入射情况下同样可以观察到脉冲自压缩现象.
关键词:
超短激光脉冲
脉冲压缩
非线性传输 相似文献
17.
Composition dependence of the photoinduced refractive-index change in lead silicate glasses 总被引:2,自引:0,他引:2
A large photoinduced refractive-index change (as great as Dn=0.21+/-0.04) is obtained in lead silicate glasses by irradiation with the frequency-quadrupled output of a Q -switched YAG laser (266 nm). An approximately exponential relationship is found between the photoinduced refractive-index change and the lead cation mole fraction over the composition range from 18.7% to 57%. The induced refractive-index change is permanent and shows no decay after heating to 360 degrees C during 1 h. Dispersion of the refractive-index change suggests that the photosensitivity is associated with changes in the intrinsic glass absorption edge. 相似文献
18.
Laser-induced microexplosion confined in the bulk of a sapphire crystal: evidence of multimegabar pressures 总被引:1,自引:0,他引:1
Juodkazis S Nishimura K Tanaka S Misawa H Gamaly EG Luther-Davies B Hallo L Nicolai P Tikhonchuk VT 《Physical review letters》2006,96(16):166101
Extremely high pressures (approximately 10 TPa) and temperatures (5 x 10(5) K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 10(14) W/cm2 converting material within the absorbing volume of approximately 0.2 microm3 into plasma in a few fs. A pressure of approximately 10 TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 10(18) K/s can, thus, be studied in a well-controlled laboratory environment. 相似文献
19.
Haiyi Sun Juan Song Chengbin Li Jian Xu Xinshun Wang Ya Cheng Zhizhan Xu Jianrong Qiu Tianqing Jia 《Applied Physics A: Materials Science & Processing》2007,88(2):285-288
We investigate the mechanism of formation of periodic void arrays inside fused silica and BK7 glass irradiated by a tightly
focused femtosecond (fs) laser beam. Our results show that the period of each void array is not uniform along the laser propagation
direction, and the average period of the void array decreases with increasing pulse number and pulse energy. We propose a
mechanism in which a standing electron plasma wave created by the interference of a fs-laser-driven electron wave and its
reflected wave is responsible for the formation of the periodic void arrays.
PACS 61.80.Ba; 42.65.Re; 42.70.Ce; 61.72.Qq; 52.35.Mw 相似文献
20.
A. Gürtler J.J. Gilijamse A.A.R. Wetzels L.D. Noordam E. Sali M. Bellini 《Optics Communications》2007,270(2):1457-339
We propose focusing by a Fresnel zone plate into a pinhole as a cost-efficient, rugged component for wavelength selection in femtosecond pulses. We show measurements of the frequency selectivity of a Fresnel zone plate for an ultra-broadband supercontinuum pulse. We verify that our zone plate does not considerably stretch the 65 fs laser pulses in time. 相似文献