共查询到20条相似文献,搜索用时 578 毫秒
1.
The size reduction of tunable micromachined filters is carried out for high-speed wavelength tuning. We fabricated micromachined filters having a miniature structure with an air gap of 300 nm and a short cantilever of 45 μm, exhibiting fast response of below 3 μs. 相似文献
2.
Potential for micromachined actuation of ultra-wide continuously tunable optoelectronic devices 总被引:1,自引:0,他引:1
H. Hillmer J. Daleiden C. Prott F. Römer S. Irmer V. Rangelov A. Tarraf S. Schüler M. Strassner 《Applied physics. B, Lasers and optics》2002,75(1):3-13
Tailored scaling represents a principle of success that, both in nature and in technology, allows the effectiveness of physical
effects to be enhanced. Mutation and selection in nature are imitated in technology, e.g. by model calculation and design.
Proper scaling of dimensions in natural photonic crystals and our fabricated artificial 1D photonic crystals (DBRs, distributed
Bragg reflectors) enable efficient diffractive interaction in a specific spectral range. For our optical microsystems we illustrate
that tailored miniaturization may also increase the mechanical stability and the effectiveness of spectral tuning by thermal
and electrostatic actuation, since the relative significance of the fundamental physical forces involved considerably changes
with scaling. These basic physical principles are rigorously applied in micromachined 1.55-μm vertical-resonator-based devices.
We modeled, implemented and characterized 1.55-μm micromachined optical filters and vertical-cavity surface-emitting laser
devices capable of wide, monotonic and kink-free tuning by a single control parameter. Tuning is achieved by mechanical actuation
of one or several air-gaps that are part of the vertical resonator including two ultra-highly reflective DBR mirrors of strong
refractive index contrast: (i) Δn=2.17 for InP/air-gap DBRs (3.5 periods) using GaInAs sacrificial layers and (ii) Δn=0.5
for Si3N4/SiO2 DBRs (12 periods) with a polymer sacrificial layer to implement the air-cavity. In semiconductor multiple air-gap filters,
a continuous tuning of >8% of the absolute wavelength is obtained. Varying the reverse voltage (U=0–5 V) between the membranes
(electrostatic actuation), a tuning range of >110 nm was obtained for a large number of devices. The correlation of the wavelength
and the applied voltage is accurately reproducible without any hysteresis. In two filters, tuning of 127 and 130 nm was observed
for about ΔU=7 V. The extremely wide tuning range and the very small voltage required are record values to the best of our
knowledge. For thermally actuated dielectric filters based on polymer sacrificial layers, Δλ/ΔU=-7 nm/V is found.
Received: 10 May 2002 / Published online: 8 August 2002 相似文献
3.
J. H. Chang Q. H. Mao S. J. Feng J. Jiang X. L. Li Y. Y. Tian C. Q. Xu W. Q. Liu 《Applied physics. B, Lasers and optics》2011,104(4):851-859
The tuning properties for the mid-IR DFG laser based on uniform grating PPLN have been investigated with tunable YDFL and
EDFL fundamental lights. Our results show that, for a fixed crystal temperature, the idler tunable range is less than 10 nm
when the EDFL is tuned. Although the pump may be allowed to be tuned in its two QPM acceptance bands, the idler tunable range
is still narrow for a fixed temperature. By optimizing the crystal temperature, however, the two pump QPM acceptance bands
may be overlapped to form one broadband QPM band, which may be used to increase the idler tunable range to 175 nm near 3.4 μm
region. The positions of the single signal and the two separate pump QPM acceptance bands can be continuously moved by adjusting
the temperature, which may also be used for enhancing the idler tuning range. By tuning the EDFL while adjusting the temperature,
a whole combined idler tuning range between 2.98 and 3.78 μm was experimentally obtained with three fixed pump wavelengths
of 1.05, 1.08 and 1.11 μm. By tuning the YDFL in the two separate QPM acceptance bands, a tuning range of 690 nm has been
demonstrated with only one fixed signal wavelength of 1.58 μm. 相似文献
4.
Widely tunable difference frequency generation around 3.4 μm using index dispersion property of PPLN
In this paper, the wide difference frequency generation (DFG) tuning characteristics around 3.4 μm are investigated by using
the index dispersion property of PPLN. With a ytterbium doped fiber laser (YDFL) and an erbium doped fiber laser (EDFL) as
the fundamental light sources, our simulation results show that the quasi-phase matching (QPM) wavelength acceptance bandwidth
(BW) for the pump is much larger than that for the signal. Although the positions of the broadened QPM pump bands vary with
the poling period and the signal wavelength, the corresponding idler tuning ranges center around 3.4 μm. With a signal wavelength
of 1.57 μm, an idler tuning range of greater than 170 nm is experimentally obtained in the 30 uniform grating PPLN. When the
signal wavelength and the poling period are respectively changed to 1.55 and 29.50 μm, wide DFG tuning operations around 3.4
μm are also achieved with the crystal temperature adjusted to adapt the change. 相似文献
5.
S. D. Liu J. F. Yang J. L. He B. T. Zhang X. Q. Yang F. Q. Liu H. W. Yang J. L. Xu H. T. Huang 《Laser Physics》2011,21(2):327-330
This paper reported a broadband tuning intracavity optical parametric oscillator (IOPO), based on the multiple grating periodical
poled lithium niobate (PPLN) pumped by a acoustic-optical (AO) Q-switched Nd:YVO4 laser. The widely tunable OPO output signal wavelength range from 1390 to 1605 nm, which was obtained by changing PPLN poling
period from 27.8 to 31.6 μm at a certain temperature of 46°C, while the continuous tuning range was measured from 1475 to
1592 nm with the PPLN poling period of 30 μm by varying the temperature of nonlinear crystal PPLN from 50 to 120°C. The maximum
output power of 0.92 W at 1534 nm with the minimum pulse width of 5.17 ns was generated under the incident pump power of 9.6
W at 808 nm. The corresponding peak power and single pulse energy were calculated to be 5.94 kW and 30.7 μJ, respectively.
The M
2-factor was measured to be 2.01 at the signal power of 0.4 W. 相似文献
6.
G.M. Gibson G.A. Turnbull M. Ebrahimzadeh M.H. Dunn H. Karlsson G. Arvidsson F. Laurell 《Applied physics. B, Lasers and optics》1998,67(5):675-677
4 (PPKTP). We generated 12 μW of radiation tunable around 1.6 μm by difference-frequency mixing of the outputs of a frequency-doubled
Nd:YLF laser at 523 nm (240 mW) and a tunable Ti:sapphire laser near 760 nm (340 mW). A temperature tuning rate of 0.73 nm/°C
for the generated wavelength and a FWHM temperature acceptance bandwidth of 6.9 °C cm was observed. The effective d33 coefficient was estimated to be ∼5 pm/V.
Received: 02 September 1998 相似文献
7.
Optical parametric oscillators for high pulse energy and high average power operation based on large aperture periodically poled KTP and RTA 总被引:3,自引:0,他引:3
M. Peltz U. Bäder A. Borsutzky R. Wallenstein J. Hellström H. Karlsson V. Pasiskevicius F. Laurell 《Applied physics. B, Lasers and optics》2001,73(7):663-670
We report on optical parametric oscillators (OPOs) based on large aperture periodically poled KTiOPO4 (PPKTP) and RbTiOAsO4 (PPRTA) pumped with high pulse energy and high average power Q-switched solid-state lasers. The OPOs were pumped with 1064-nm
pulses of a diode-pumped Nd:YVO4 laser at 20 kHz repetition rate. The emitted signal wavelengths were 1.72 μm and 1.58 μm and the idler wavelengths were 2.79 μm
and 3.26 μm, respectively. Pumping the PPKTP OPO with 7.2 W and the PPRTA OPO with 8 W average power, 2 W and 1.3 W total
OPO output powers were generated. Two-dimensional measurements of the total OPO output power, the signal wavelength and the
signal bandwidth in dependence on the crystal location indicated a good uniformity of the quasiphasematching structure over
the entire 3-mm-thick crystals. This allowed pumping with larger pump beams and therefore with pulse energies of tens of millijoules.
Pumping with different flash-lamp-pumped lasers, good OPO performance and high output pulse energies could be achieved for
all pump lasers. Maximum input pulse energies of 56 mJ gave output pulse energies of as much as 18 mJ. The temperature tuning
behaviors of both OPOs were measured, showing excellent agreement with calculated temperature tuning curves. New equations
for temperature dispersion in RTA are presented. These results show that large-aperture PPKTP and PPRTA crystals are well
suited for tunable nanosecond OPO operation with multi-watt average pump power and several tens of millijoules pump pulse
energies.
Received: 7 September 2001 / Published online: 7 November 2001 相似文献
8.
L. Piraux S. Dubois A. Fert L. Belliard 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(4):413-420
A theory, based on earlier work by Valet and Fert, is first presented to describe the influence of temperature on the perpendicular
giant magnetoresistance (GMR) in multilayers. Then we present GMR measurements performed at T=77 K and at room temperature on Co/Cu multilayered nanowires with layer thicknesses ranging from a few nm to 1 μm. We use
our model to obtain a good quantitative fit to the experimental results in both the short spin diffusion length limit and
out of this limit. We discuss the temperature dependence of the bulk parameters, the scattering spin asymmetry coefficient
and spin diffusion length in the Co layers.
Received: 25 January 1998 / Accepted: 6 May 1998 相似文献
9.
W. Denzer G. Hancock A. Hutchinson M. Munday R. Peverall G.A.D. Ritchie 《Applied physics. B, Lasers and optics》2007,86(3):437-441
We have utilised a periodically poled LiNbO3 crystal with a waveguide structure to produce up to 146 μW of mid-IR radiation around 2976 cm-1 by difference frequency mixing of 1064 nm pump radiation with 1558 nm signal radiation. A conversion efficiency of 45% W-1 is achieved within a crystal of length 50 mm, and temperature tuning curves are reported. The resultant idler radiation is
exploited for high resolution absorption studies of both methane and methanethiol. The absorption cross-sections for methanethiol
in the region of 2979 cm-1 are measured and found to be ∼10-19 cm2, the relevance of these results to breath and headspace analysis of clinical samples containing volatile sulphur compounds
is briefly discussed.
PACS 42.62.Fi; 42.65.Ky 相似文献
10.
根据Vernier效应可大幅度提高滤波器自由光谱范围和调谐范围,设计了一种热光可调谐级联微环滤波器. 利用传输矩阵方法和有限元方法从理论上计算了对于第一级微环半径为48 μm,第二级半径为50 μm的级联微环滤波器的自由光谱范围和调谐范围可以达到75.6 nm,而功耗仅为103.1 mW,这是目前为止我们 所知的基于微环谐振腔的硅基热光可调谐滤波器中最大的自由光谱范围和在如此低功耗下最大的调谐范围. 利用有限元方法,还计算了半径为50 μm微环的热光调谐响应时间,上升沿时间为3.5 μs,下降沿时间仅为0.8 μs. 相似文献
11.
Lin Wang Heqing Yang Hua Zhao Ru Yu Shi Liu Bao Bin Liu 《Applied Physics A: Materials Science & Processing》2011,102(1):61-68
The present work reports on novel four-layer thermally driven piezoresistive cantilevers implemented in one- and two-dimensional
arrays for parallel proximity scanning. There, the heater (metallic meander), the piezoresistive deflection sensor, and the
metal actuation film with significantly higher thermal expansion coefficient make up separate layers. Actuation efficiency
and cross-talk of the novel cantilever design are studied and compared with two recent designs: thin metallic film and ion-implanted
heater. The novel actuator, integrated on a 240 μm long and 3 μm thick silicon cantilever and supplied by V
dc=1 V enables deflections up to 5 μm of the AFM-tip with an actuation efficiency of about 170 nm/mW and suppressed cross-talk
between actuator and sensor. 相似文献
12.
The operation and characterization of a high-repetition-rate singly-resonant picosecond optical parametric oscillator based
on the non-linear material KTiOAsO4 and synchronously pumped by a Kerr-lens-mode-locked Ti:sapphire laser at 81 MHz is described.
By utilizing non-critical type II phase-matching in a 10 mm crystal, average near-infrared output powers of 403 mW have been
generated at 31% extraction efficiency. The oscillator exhibits a pump power threshold of 230 mW and with the available mirror
set can provide signal tuning over 1.116–1.281 μm and idler tuning over 2.260–3.160 μm by tuning the pump wavelength over
770–896 nm. Without dispersion compensation, near-transform-limited signal pulses with durations of 1.01–1.03 ps and idler
pulses with 1.61–2.91 ps duration have been obtained for 1.2 ps input pump pulses.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
13.
C. Kränkel J. Johannsen R. Peters K. Petermann G. Huber 《Applied physics. B, Lasers and optics》2007,87(2):217-220
We report power scaling of the Yb3+:LaSc3(BO3)4 (Yb:LSB) laser material in thin disk configuration. Employing a 300-μm thick Yb(25 at. %):LSB crystal, the continuous-wave
output power around 1.0 μm wavelength reaches 40 W for 95 W of pump power at 974 nm; the overall optical-to-optical efficiency
and the slope efficiency are 0.43 and 0.48, respectively. Preliminary experiments show continuous tuning of the laser output
between 991 nm and 1085 nm.
PACS 42.55.Xi; 42.60.Fc; 42.55.Rz 相似文献
14.
S. Das S.F. Ahmed M.K. Mitra K.K. Chattopadhyay 《Applied Physics A: Materials Science & Processing》2008,91(3):429-433
Effects of temperature and the aspect ratio on the electron field emission properties of vertically aligned carbon nanofibers
in thin-film form were studied in detail. Vertically aligned carbon nanofibers have been synthesized on silicon substrates
via a direct current plasma enhanced chemical vapor deposition technique. Surface morphologies of the films were studied by
an atomic force microscope. It was found that the length of the nanofibers increased and the diameter decreased as the thickness
of the Ni catalyst film decreased. The threshold field for the electron field emission was found to be in the range from 4.3
to 5.4 V/μm for carbon nanofibers having different aspect ratios. The threshold field for carbon nanofibers having diameter
∼ 200 nm and aspect ratio ∼7.5 was found to decrease from 4.8 to 2.1 V/μm when the temperature was raised from 27 to 350 °C.
This dependence was due to the change in work function of the nanofibers with temperature. The field enhancement factor, the
current density and the effective work function were calculated and used to explain the emission mechanism.
PACS 81.07.De; 61.10.-i; 79.70.+q; 73.30.+y 相似文献
15.
We describe a mopa structured all-fiber 15 μm fiber amplifier cascade. A single-mode diode laser generating 1064 nm wavelength,
several nanosecond pulses at 100 Hz repetition was adopted to seed a corepumping amplifier featuring a 6 μm core Yb-doped
fiber. Multi-stage pulse-pumping technology was applied to eliminate ASE as much as possible and ease the heat load of the
system that leads to the freedom of temperature control of the laser diode. The master oscillator-power amplifier (MOPA) generated
1064 nm, 18 ns pulse-width, 100 Hz repetition of 220 μJ single pulse energy, peak power >12 kW with single transverse output.
The pulse energy of 220 μJ is the largest to date in the all-fiber MOPA amplifier with core diameter around 15 μm to our knowledge. 相似文献
16.
Kazunori Kadota Takenobu Yamamoto Atsuko Shimosaka Yoshiyuki Shirakawa Jusuke Hidaka Masato Kouzu 《Journal of nanoparticle research》2011,13(12):7209-7218
The mechanism on aggregation of spindle granular particles of calcite was investigated for the carbonation of calcium hydroxide
in aqueous suspension for the purpose of controlling morphology of CaCO3. The experimental carbonation process was carried out in a semi-batch bubble column reactor under different conditions. Although,
fine rhombic nano-particles diameter ranged from 100 to 200 nm were obtained at 291 K, a higher temperature of 300 K provided
spindle granular particles with a length of 1.0–1.5 μm and a width of 0.3–0.5 μm. The average crystallite size was 28 nm for
the fine rhombic nano-particles and 43 nm for the spindle granules. Zeta potential measurement for the spindle granules indicated
that the suspension tended to be aggregated during the carbonation process. The effect of the degree of particle aggregation
on the shape of the obtained calcite particles was studied by Monte Carlo simulations. Our simulation results elucidated the
dependence of aggregation on unit particles, i.e., primary particles, on the experiment carbonation condition where the spindle
granules were formed out of the unit particles under the same condition as the experiments. In addition, the formation mechanism
of the granules was investigated by applying classical nucleation theory to the present simulations. 相似文献
17.
Cadmium sulfide (CdS) nanostructured materials were synthesized by a wet chemical route without using any capping agent. X-ray diffraction pattern showed the typical interplanar spacings corresponding to the cubic phase of CdS. Transmission electron microscopy studies showed the nanowires formation with length in the range 0.1–1.5 μm and the diameter 25–30 nm. UV–visible optical spectroscopy study was carried out to determine the bandgap of the nanostructured CdS thin films and it showed blue shift with respect to the bulk value. Variation of band gap energies with annealing temperature was also studied in detail. Room temperature photoluminescence of the nano-CdS films was measured and the spectrum showed a broad band centered at ~567 nm, which originated from trap states existing in the forbidden energy gap. 相似文献
18.
Automatically tunable continuous-wave optical parametric oscillator for high-resolution spectroscopy and sensitive trace-gas detection 总被引:1,自引:0,他引:1
A.K.Y. Ngai S.T. Persijn G. von Basum F.J.M. Harren 《Applied physics. B, Lasers and optics》2006,85(2-3):173-180
We present a high-power (2.75 W), broadly tunable (2.75–3.83 μm) continuous-wave optical parametric oscillator based on MgO-doped periodically poled lithium niobate. Automated tuning of the pump laser, etalon and crystal temperature results in a continuous wavelength coverage up to 450 cm-1 per poling period at <5×10-4 cm-1 resolution. The versatility of the optical parametric oscillator as a coherent light source in trace-gas detection is demonstrated with photoacoustic and cavity ring-down spectroscopy. A 17-cm-1-wide CO2 spectrum at 2.8 μm and multi-component gas mixtures of methane, ethane and water in human breath were measured using photoacoustics. Methane (at 3.2 μm) and ethane (at 3.3 μm) were detected using cavity ring-down spectroscopy with detection limits of 0.16 and 0.07 parts per billion by volume, respectively. A recording of 12CH4 and 13CH4 isotopes of methane shows the ability to detect both species simultaneously at similar sensitivities. PACS 42.65.Yj; 42.72.Ai; 42.62.Fi 相似文献
19.
Fatemeh Abrishamian Shinichi Nagai Shinya Sato Masaaki Imai 《Optical and Quantum Electronics》2008,40(9):665-676
Spectral response of acoustically induced microbending through thin optical fiber is discussed from mode-coupling of core
and cladding modes. The thin fiber is analyzed in three-layered structure (core-cladding-air) to gain insights into acousto-optic
modulation. We explained the dependence of core and/or cladding diameters on acoustic source parameters from numerical calculations.
According to the calculations, we successfully fabricated all-optical tunable filter using this thin fiber that yields an
efficient mode-coupling at flexural wave frequencies less than 1MHz. To increase the acousto-optic effect, we used a specially
designed thin optical fiber (80 μm of cladding diameter) in the section where flexural wave is produced, and spliced both
ends of the thin fiber to the tapered 125 μm fibers. The frequency and voltage tuning of fabricated filter is also confirmed
by changing the driven frequency and applied voltage of the PZT, respectively. This result suggests a possibility of fiber-optic
device application as all-optical tunable filter at 1.55 μm. 相似文献
20.
C. Berger Y. Yi Z.L. Wang W.A. de Heer 《Applied Physics A: Materials Science & Processing》2002,75(3):363-365
Following the experiments of Frank et al. [1], which demonstrated quantum transport in multiwalled carbon nanotubes, there
have been several experiments that appear to contradict the main conclusion of that paper, which is that the transport of
a MWNT at room temperature is ballistic. Here we demonstrate that the intrinsic resistance of clean-arc-produced carbon nanotubes
is at most 200 Ω/ μm, which implies that the momentum mean free path is greater than 30 μm, which in turn is much larger than
the tube length. This implies that these tubes are ballistic, according to the standard definition of ballistic transport.
We also show that the contact resistance with mercury is quite large: a nanotube in contact with Hg over 100 nm of its length
still represents a 3000 Ω resistance.
Received: 14 September 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献