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1.
Single-step writing of Bragg grating waveguides in fused silica with an externally modulated femtosecond fiber laser 总被引:1,自引:0,他引:1
For the first time to our knowledge, high-strength (>30 dB) first-order Bragg grating waveguides were fabricated in bulk fused silica glass in a single-scanning step by modulating a high-repetition-rate femtosecond fiber laser with an external acousto-optic modulator. The modulation induced a waveguide segmentation by delivering controlled bursts of laser pulses to define an array of partially overlapped refractive index voxels. With appropriate choice of modulation frequency and sample scanning speed, low loss waveguides could be formed at high writing speeds to yield sharp Bragg spectral resonances tunable over the 1300 to 1550 nm telecom band. Effects of acousto-optic modulation duty cycle on propagation loss and grating strength are characterized. This modulation method offers facile control and integration of multiwavelength Bragg grating devices to enhance overall functionality of optical circuits in three-dimensional geometries. 相似文献
2.
Surface-relief gratings were directly fabricated onto a glass surface by UV-visible laser irradiation. The glass surface was pretreated by molten salt, including Ag ions. Periodic intensity modulation of the laser light was conducted with a phase mask or by an interference technique. A pattern generated by intensity modulation was precisely transcribed onto the glass surface and a surface-relief grating was formed. The period and depth of the grating were 0.5 to 10 microm and less than 0.8 microm, respectively. The cross-sectional profile of the grating was sinusoidal or triangular, with very smooth surface morphology. 相似文献
3.
Two-dimensional periodic microstructures, including both microholes and micro-orbicular platforms, have been fabricated on the surface of silica glass by a single shot of three interfered femtosecond laser pulses. The three-dimensional structure of a fabricated hexagonal lattice can be revealed by atomic force microscopy. The formation of the microstructure and the dynamic process of the interaction between the femtosecond laser and the silica glass have been discussed. 相似文献
4.
Periodic nanostructures are observed inside silica glass after irradiation by a focused beam of a femtosecond Ti:sapphire laser. Backscattering electron images of the irradiated spot reveal a periodic structure of stripelike regions of approximately 20 nm width with a low oxygen concentration, which are aligned perpendicular to the laser polarization direction. These are the smallest embedded structures ever created by light. The period of self-organized grating structures can be controlled from approximately 140 to 320 nm by the pulse energy and the number of irradiated pulses. The phenomenon is interpreted in terms of interference between the incident light field and the electric field of the bulk electron plasma wave, resulting in the periodic modulation of electron plasma concentration and the structural changes in glass. 相似文献
5.
Á. Sipos A. Szalai M. Görbe M. Szekeres M. Csete I. Dékány 《Applied Surface Science》2009,255(10):5138-5145
Plasmonic structures are prepared on bimetal films evaporated onto glass substrates applying a multi-step process, and atomic force microscopy is utilized to study the structures after each step. Sub-micrometer gratings are generated on polycarbonate films spin-coated onto silver-gold bimetal layers by interference lithography (IL) applying the fourth harmonics of a Nd:YAG laser. These polymer gratings are used as prepatterned templates in order to deposit silica colloid spheres by spin-coating. It is shown that the conditions of periodic silica sphere-array formation along the template valleys are sufficiently large grating modulation depth, appropriate ratio of silica sphere diameter to grating period, and optimized speed of spinning. The periodic silica sphere arrays are illuminated by a homogeneous KrF excimer laser beam, and periodically arrayed sub-wavelength holes are drilled into bimetal films via colloid sphere lithography (CSL). The characteristic dimensions of the resulted plasmonic structures are defined by the polymer grating period and by the silica colloid sphere diameter. Attenuated total reflection spectroscopy is performed exciting plasmons on different metal-dielectric interfacial structures by the second harmonic of a continuous Nd:YAG laser. The polar and azimuthal angle dependent grating-coupling and scattering effects of the complex periodic structures on the resonance characteristic of plasmons is demonstrated. 相似文献
6.
Three-dimensional hole drilling of silica glass from the rear surface with femtosecond laser pulses 总被引:4,自引:0,他引:4
By moving silica glass in a preprogrammed structure, we directly produced three-dimensional holes with femtosecond laser pulses in single step. When distilled water was introduced into a hole drilled from the rear surface of the glass, the effects of blocking and redeposition of ablated material were greatly reduced and the aspect ratio of the depth of the hole was increased. Straight holes of 4-mu;m diameter were more than 200 microm deep. Three-dimensional channels can be micromachined inside transparent materials by use of this method, as we have demonstrated by drilling a square-wave-shaped hole inside silica glass. 相似文献
7.
8.
Jürgen Ihlemann 《Applied Physics A: Materials Science & Processing》2008,93(1):65-68
Precise patterning by laser ablation requires sufficient absorption. For weak absorbers like fused silica indirect methods
using external absorbers have been developed. A novel approach using a solid SiO absorber coating is described. Irradiation
by an ArF excimer laser (wavelength 193 nm) is leading to ablation of the coating and, at sufficiently high fluence, of the
fused silica substrate. The remaining coating in the unexposed areas is removed afterwards by large area irradiation. The
fluence threshold for substrate ablation using a 28 nm thick absorber layer is about 1.1 J/cm2. Single pulse ablation rates of up to 800 nm and a surface roughness of R
a<5 nm are obtained. High resolution grating patterns with 400 nm period and a modulation depth of 80 nm are possible. The
process can be described as controlled plasma mediated ablation. 相似文献
9.
J. Liu Z. Zhang Z. Lu G. Xiao F. Sun S. Chang C. Flueraru 《Applied physics. B, Lasers and optics》2007,86(1):151-154
Fabrication and stitching of internal 2D, 1D and multi-layer micro-gratings in fused silica glass using amplified Ti:sapphire femtosecond laser were reported. These gratings have the pitch of 4 μm and the size of 400 μm×400 μm. For a two-layer 1D micro-grating where a second-layer grating was overwritten on a first-layer grating at the exact X,Y position and the different Z depth, the diffraction efficiency can reach more than 25% due to the grating thickness increase. If a second-layer grating was stitched with a first-layer by the shift of 2 μm in the X direction and at the different Z depth, the diffraction angle was doubled but the diffraction efficiency was about 9%. The last result has the potential application for fabricating high-density micro-/nano-structures beyond the diffraction limit through 3D stitching. PACS 42.79.Dj; 42.40.Lx; 42.62.Cf 相似文献
10.
We demonstrate that a Raman sensor integrated with a micro-heater, a microfluidic chamber, and a surface-enhanced Raman scattering (SERS) substrate can be fabricated in a glass chip by femtosecond laser micromachining. The micro-heater and the SERS substrate are fabricated by selective metallization on the glass surface using a femtosecond laser oscillator, whereas the microfluidic chamber embedded in the glass sample is fabricated by femtosecond laser ablation using a femtosecond laser amplifier. We believed that this new strategy for fabricating multifunctional integrated microchips has great potential application for lab-on-a-chips. 相似文献
11.
Controllable grating fabrication by three interfering replicas of single femtosecond laser pulse
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The controllable periodic M-shape gratings are fabricated
on the surface of silica glass by three coplanar interfering beams
from a single femtosecond pulse. The configuration of the M-shape
periodic structure is characterized by optical microscopy and atomic
force microscopy. The experimental results and the theoretical
simulation show that the period and the modulation depth ratio
between the neighboring grooves of the fabricated gratings can be
controlled by adjusting the collision angles and pulse energy of
the three beams, respectively. 相似文献
12.
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
13.
Lingling Qiao Fei He Chen Wang Ya Cheng Koji Sugioka Katsumi Midorikawa 《Applied Physics A: Materials Science & Processing》2011,102(1):179-183
We report on the integration of microlens and microfluidic channels in fused silica glass chip using femtosecond laser micromachining.
The main process includes three procedures: (1) femtosecond laser scanning for forming a hemispherical surface and a Y-shaped
channel in the fused silica glass; (2) chemical etching of the sample for removal of the modified areas; and (3) oxyhydrogen
(OH) flame polish for smoothening the surface of the microlens. In addition, we demonstrate that the fabricated microlens
exhibits good imaging performance with a 5× magnification, showing great potential in future lab-on-a-chip applications. 相似文献
14.
A 1.2 microm (height) x 125 microm (depth) x 500 microm (length) microslot along a fiber Bragg grating was engraved across the optical fiber by femtosecond laser patterning and chemical etching. By filling epoxy in the slot and subsequent UV curing, a hybrid waveguide grating structure with a polymer core and glass cladding was fabricated. The obtained device is highly thermally responsive with linear coefficient of 211 pm/ degrees C. 相似文献
15.
Csaba Vass Károly Osvay Tamás Véső Béla Hopp Zsolt Bor 《Applied Physics A: Materials Science & Processing》2008,93(1):69-73
Submicrometer period fused silica gratings were produced by two-beam interferometric laser-induced backside wet etching technique
(TWIN LIBWE). The fourth harmonic of a Nd:YAG laser beam was spatially filtered in two steps, and the smoothened beam was
split into two parts and interfered at incident angles of 60°, 30°, 14°, and 7.7°, respectively, on the backsides of fused
silica plates that were in contact with a liquid absorber. The periods of the produced fused silica gratings were, respectively,
154 nm, 266 nm, 550 nm, and 990 nm. In the next step, TWIN-LIBWE setup was completed by using a coupling rectangular prism
in order to reach immersion setup, which made possible to fabricate 104 nm period fused silica grating. This is the smallest
laser-generated grating constant in fused silica at present.
The morphology of the etched gratings was characterized by atomic force microscope. Important parameters (modulation depth,
low-pass filtered waviness, quality factor) of the produced gratings were determined. Evolution of the grating parameters
was also studied in the 990 nm case: the dependence of modulation depth, waviness, and quality factor on the number of laser
pulses was investigated. 相似文献
16.
Multimicrogratings are one-off written on silicate glass by two interfered femtosecond pulsed laser beams with the aid of a mask. The period and depth of the multimicrogratings are revealed by optical microscopy and atomic force microscopy. The depth is dependent on both the colliding angle between the two interfered laser beams and the laser pulse energy, but the period relies on the colliding angle only. We also observe a series of grooves formed at the middle of each bulge of the multimicrogratings and attribute it to the higher-order modulation arising from second-harmonic generation of the femtosecond laser pulse during the one-off writing processes. 相似文献
17.
18.
Zhongyi Guo Jinmei Feng Keya Zhou Yanjun Xiao Shiliang Qu Jung-Ho Lee 《Applied Physics A: Materials Science & Processing》2012,108(3):639-644
The interactions between femtosecond (fs) laser pulses and a thin Au film deposited on a silica glass substrate were systematically investigated based on experimental data. Different structures, including microholes, nanoholes, and nanobumps, are obtained when pulses with different energies are incident on the surface of a gold film. The experimental results are discussed according to specific experimental parameters. Two physical models were constructed in order to explain the experimental results. The formation of nanoholes in a silica substrate is attributed to etching by higher order harmonic generations (HHG) when the femtosecond laser pulse interacts with the generated plasma layer, while the formation of nanobumps on the surface of an Au film is attributed to the elastic and plastic characteristics of the metal film under laser pulse irradiation. 相似文献
19.
Phase-shifted Bragg grating waveguides (PSBGWs) were formed in bulk fused silica glass by femtosecond laser direct writing to produce narrowband (22±3) pm filters at 1550 nm. Tunable π and other phase shifts generated narrow passbands in controlled positions of the Bragg stopband, while the accurate placement of multiple cascaded phase-shift regions yielded a rectangular-shaped bandpass filter. A waveguide birefringence of (7.5±0.3)×10(-5) is inferred from the polarization-induced spectral shifting of the PSBGW narrowband filters. 相似文献
20.
Yang Yang Jianjun Yang Chunyong Liang Hongshui Wang Xiaonong Zhu Dengfeng Kuang Yong Yang 《Applied Physics A: Materials Science & Processing》2008,92(3):635-642
Generation of self-organized sub-wavelength surface structures on a nickel–titanium alloy plate by femtosecond laser pulses
is investigated experimentally through line-scribing experiments in air. It is found that Bragg-like relief gratings, with
the orientation perpendicular to the laser polarization, are formed over the entire laser-scribed regions. The average period
is measured as 630±30 nm. Distinctive features of these novel surface structures include nanoparticle-covered grating ridges
and the maintainable spatial period regardless of incidence angles. With different laser parameters and sample scan speeds,
sub-wavelength grating structures can evolve into cellular-like nanotextures. Optimal conditions for forming these surface
structures are determined in terms of laser energy and scan speed. Elementary analyses of the structured surfaces by X-ray
diffraction and photoelectron spectroscopy reveal that both the crystal structures and the chemical elements can remain in
their original states, but the surface grains are refined and the atomic percentages are varied after femtosecond laser treatments. 相似文献