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1.
Microdisk resonator filters, an alternative to microring resonator filters, are studied by means of vectorial three dimensional finite element method simulations. Their performance characteristics are highlighted for different microdisk radii, and compared with those of the respective, footprint-wise, microring filters. We show that microdisk filters are advantageous, as the resonator involved exhibits smaller radiation losses. Extinction ratios as high as 30 dB are possible by properly tuning the gap separating the waveguide from the microdisk in each case. Transmission dips due to higher-radial-order modes that drastically change the transmission picture appear only for very large microdisk radii. 相似文献
2.
W. W. Krühler R. D. Plättner W. Stetter 《Applied Physics A: Materials Science & Processing》1979,20(4):329-334
The room temperature cw oscillation at 1.05 and 1.32 μm of lithium neodymium tetraphosphate [LiNd(PO3)4, LNP] lasers in an external resonator and, for the first time, also in a Fabry-Perot resonator with directly applied mirrors
is reported. The growth and fluorescence properties of the LNP crystals are briefly described. Laser parameters such as threshold
pump power, output power, differential efficiency, optical gain, emission cross section and laser modes are both measured
and calculated. Laser experiments show the threshold pump power to be lower for 1.05 μm than for 1.32 μm emission because
of the smaller emission cross section; the pump power density is lower for the external resonator than for the Fabry-Perot
resonator because of its higher mode losses. 相似文献
3.
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
4.
R. A. Yadav T. K. Yadav M. K. Maurya D. P. Yadav N. P. Singh 《Indian Journal of Physics》2009,83(10):1421-1438
Electromagnetic field analysis of shielded composite dielectric spherical resonator in which the dielectric sphere is composed
of two concentric spheres with different dielectric materials has been made. Characteristic equations for the TEnmℓ and TMnmℓ modes have been derived. From these characteristic equations, the resonant frequencies and quality factors have been calculated
using numerical method. Computations of the resonant frequencies and quality factors have been made for resonators with parameters
suitable for the optical and microware regions.
In this paper we have presented the analysis and the results obtained from the numerical computations for shielded composite
dielectric spherical resonator in which the dielectric sphere is composed of two concentric spheres with different dielectric
materials. Starting from the Maxwell’s equations for such a resonators have been derived and resonant frequencies and quality
factor’s have been calculated for the TEnmℓ and TMnmℓ modes using numerical method. 相似文献
5.
The effect of resonator length on ZnGeP2 doubly resonant optical parametric oscillator was reported in this letter. With the employment of a Tm,Ho:GdVO4 laser as the pump source at 2.05 μm, we have found that there are obvious peaks of the output power when the resonator lengths
are matched to the length of the pump source. The ZGP OPO can generate a maximum output power of 4.27 W at 3.80 μm signal
and 4.45 μm idler when the resonator length matches that of the pump source. 相似文献
6.
M. Szymaki 《Applied physics. B, Lasers and optics》1981,24(1):13-20
Simultaneous laser operation at the wavelengths of λ1=637 and λ2=717 in Pr0.5La0.5P5O14 single crystals was observed. The crystals were excited by nanosecond publses from a Coumarin 2 dye laser (λ=450 nm). Laser
emissions and their interdependence were studied both in crystals without an external resonator and in crystals placed within
a plane parallel resonator. The energetic, time and frequency characteristics for both laser actions were examined. The effect
of bifrequential emission was also found in crystals of different ratios of Pr and La ions concentration and in pure praseodymium
pentaphosphate. 相似文献
7.
J. Alnis A. Matveev N. Kolachevsky T. Wilken R. Holzwarth T. W. Hänsch 《The European physical journal. Special topics》2008,163(1):89-94
We report on an external cavity diode laser at 972 nmstabilized to a mid-plane mounted Fabry-Perot (FP) resonator with afinesse
of 400000. The 0.5 Hz optical beat note line width betweentwo similar lasers (Allan deviation 2 × 10-15) is limitedby thermal noise properties of two independent FP resonators. Thelong term drift of the FP resonator and mirror
substrates made fromUltra-Low-Expansion glass (ULE) is small and can be well predictedon time intervals up to many hours if
the resonator is stabilized atthe zero thermal expansion temperature Tc. Using a Peltierelement in a vacuum chamber for temperature stabilization allowsstabilization of the FP cavity to Tc which is usually below theroom temperature. Beat note measurements with a femtosecond opticalfrequency comb referenced to
a H-maser during 15 hours have shown awell defined linear drift of the FP resonance frequency of about 60 mHz/s with residual
frequency excursions of less than ±20 Hz. 相似文献
8.
Y.H. Wang Y.C. Qu W.J. Zhao D.M. Ren X.Y. Hu 《Applied physics. B, Lasers and optics》2008,92(2):237-241
We present a single longitudinal mode (SLM) TEA CO2 laser oscillation by using a three-mirror resonator with a Fabry–Pérot etalon. The etalon was inserted in the optical path
taken out from the main resonator of the CO2 laser for protecting the etalon from damage on the surface. A modified numerical model of the three- mirror resonator was
investigated for design the laser. SLM pulse from the TEA CO2 laser was achieved, and the experimentally measure values were found to have good agreement with the numerical model. The
maximum pulse energy of reliable SLM emission is obtained in excess of 200 mJ at 9.57 μm. The reliability of producing SLM
pulses was higher than 90%, and there was no damage on the etalon
PACS 42.55.Lt; 42.60.Fc 相似文献
9.
V. G. Ostroumov F. Heine S. Kück G. Huber V. A. Mikhailov I. A. Shcherbakov 《Applied physics. B, Lasers and optics》1997,64(3):301-305
An intracavity frequency-doubled 10%Nd : LaSc3(BO3)4 (Nd : LSB) laser was investigated in different resonator configurations and in different operation modes under continuous
wave (cw) and quasi-cw laser-diode pumping. With a Cr4+ : YAG passive modulator and a KTP crystal the second-harmonic output power at 531 nm amounted to 190 mW in Q-switched TEM00 mode at 750 mW of pump power. In a sandwich resonator, when all the optical elements were in direct contact with each other,
0.8 W of green output power was obtained in cw mode under 2.7 W of pump power with a slope efficiency of 44%. In the same
setup under fiber-coupled diode-laser array pumping (5.6 W of incident power), 1.2 W of green output power was achieved in
cw mode and 1.4 W in quasi-cw mode.
Received: 30 April 1996/Revised version: 1 July 1996 相似文献
10.
In this paper, we report some experimental results concerning several types of loss measurements of Er3+:Ti:LiNbO3 optical waveguides by using optical methods. Using the Fabry-Pérot interferometry method, we evaluated the attenuation coefficient
of an optical waveguide resonator for a laser radiation having λ = 1.55 μm. We also evaluated the insertion losses, polarization dependent losses, and coupling with external losses. Additionally,
from the transmitted spectra of the symmetrical monomode Fabry-Pérot optical waveguide resonator, we were able to evaluate
the value of the group effective refractive index. 相似文献
11.
Summary A long-pulse (>3 μs) CO2 laser has been built using a negative-branch, frequency-selective, unstable resonator. The results obtained with this device
are shown.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
12.
A Pockels cell Q-switch has been operated in a manner analogous to a saturable absorber by initially keeping the cell partly
open for the first 1000 or so double passes and then opening it completely at a pre-set resonator power. This then allows
simple and reliable selection of a single longitudinal mode. A detailed discussion is given of the design considerations which
lead to the correct choice of mode-selecting device. With three different devices, a TEM00 mode Nd:CaWO4 laser has produced 400 kW pulses in a single longitudinal mode with a shot-to-shot frequency stability of ∼ 0.01 cm−1. 相似文献
13.
In this paper an alternative approach for measurement of στ product for 4
F
3/2→4
I
11/2 transition of Nd3+ doped YVO4 crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane-plane resonator
and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable.
The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is
measured by Gaussian fit to the intensity profiles of the pump beam. The value of στ product of Nd:YVO4 crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple
method for direct measurement of στ product of laser crystals. 相似文献
14.
A Helmholtz resonator is a shell Ωshell separating a compact cavity Ωint from a noncompact outer domain Ωout. A small opening Ω
δ
in the shell connects the cavity with the outer domain, causing the transformation of real eigenfrequencies of the Neumann
Laplacian in the cavity into the complex scattering frequencies of the full spectral problem for the Neumann Laplacian on
Ω = ℝ3\Ωshell.
The Kirchhoff model of 1882, see [21], gives a convenient ansatz
for the approximate calculation of the outer component of the scattered wave of the full spectral problem on Ω in terms of
the scattered wave Ψout
N
(x, ν, λ) and the Green function G
out
N
(x, a, λ) of the Neumann Laplacian on the outer domain, with a pole at the pointwise opening Ω
δ
≈ a.
In this paper, we suggest an explicit formula for the Kirchhoff coefficient A
out, based on the construction of a fitted solvable model for the Helmholtz resonator with a narrow short channel Ω
δ
connecting the cavity with the outer domain. The correcting term of the scattering matrix of the model serves as a rational
approximation, on a certain spectral interval, for the correcting term of the full scattering matrix of the Helmholtz resonator.
Dedicated to the memory of Vladimir Andreevich Borovikov, who often chose a problem as an engineer and solved it by creating
new and surprising mathematics 相似文献
((1)) |
15.
V. N. Ishchenko V. N. Lisitsyn A. M. Razhev 《Applied Physics A: Materials Science & Processing》1977,13(1):55-58
NdxLa1−xP5O14 (0.25≦x≦1) single crystals, placed within a confocal optical resonator, were pumped with ruby laser fundamental and second-harmonic
nanosecond pulses. In both cases laser oscillations at 1.05 μm exceeding in duration many times the pumping pulse were obtained. 相似文献
16.
Spectral lines of Yb lasing in 1.03–1.05 μm region structured by 50–200 μm spots were found at focusing a pulsed LiF:F2+ color center laser of 0.5–5.0 GW/cm2 intensity on highly doped Yb:YAG or Yb:glass plates in a resonator. Small spots at the spectrograph located ≈ 1 m apart from
the resonator indicated a “sub-diffraction” directivity of Yb generation, 1–2 orders better than the diffraction limit 10−3–10−2 rad determined by the pumped volume dimensions. Observed features of Yb emission are explained assuming off-axis oscillations
in Yb laser on phase-synchronized photons due to a strong spatial-angular selection of radiation in the resonator. Propagation
of near diffraction free beams at angles to the axis built at the spectrograph slit for every 10–15 ns pulse of Yb generation
a magnified “image” of a structure of generating channels in the active medium. This image projection brought a corresponding
structure of spots in Yb spectra. It was found that channels may be formed due to a high-frequency spatial modulation (micrometers
scale) of the refractive index profile in samples caused by the oscillating amplitude of thermoelastic stresses in the pumped
medium. Obtained data demonstrate a possibility to study (with high spatial and temporal resolution) non-equilibrium stales
of materials in small volumes using laser radiation emerging from these objects. This study results evidence for the novel
concept of the spatial distribution of electromagnetic field of a photon: not in the form of a “travelling” wave but in the
form of a wave with maxima and nodes located at fixed positions along the photon propagation direction. 相似文献
17.
B. N. Gritsyuk T. S. Moshkova A. D. Ogorodnik I. M. Rarenko T. A. Volyanskaya 《Journal of Applied Spectroscopy》1999,66(4):651-653
We suggest using crystals of the In4(Se3)1−xTe3x solid solution for manufacturing absorption optical filters with the boundary wavelength regulated from 1.7 to 2.5 μm by
changing the composition of the solution. The refractive index is determined for different compositions, and the possibility
of making the filters antireflecting is shown. The advantages of the proposed filters are connected with the specific features
of the absorption edge of crystals and their structure.
To whom correspondence should be addressed.
Chernovtsy State University, 2, Kotsyubinskii Str., Chernovtsy, 274012, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 66, No. 4, pp. 577–579, July–August, 1999. 相似文献
18.
M. Gomes da Silva A. Miklós A. Falkenroth P. Hess 《Applied physics. B, Lasers and optics》2006,82(2):329-336
Photoacoustic spectroscopy, in combination with a pulsed grazing-incidence optical parametric oscillator (GIOPO), was used
for sensitive detection of nitrous oxide (N2O) in ambient air. The ν1+ν3 combination band of N2O was excited with the idler beam of the GIOPO in the 2.76 μm–2.91 μm spectral region, where CO2 and water-absorption lines are also present. Three chemical filters filled with KOH, CaCl2, and P2O5 were used to reduce the CO2 and water concentrations to the level of several parts per billion (109) by volume (ppbv). Photoacoustic spectra containing several absorption lines were recorded and the concentration was determined
by an integral evaluation method and a fast Fourier transform evaluation method. The photoacoustic signal was calibrated by
a standard mixture of 50.6 parts per million by volume (ppmv) of N2O in synthetic air. Values of 311±5 ppbv, 314±5 ppbv, and 316±5 ppbv were found for three ambient samples collected at nearby
roads.
PACS 42.62.Fi; 42.65.Yj; 07.07.Df; 42.68.Ca 相似文献
19.
R. Barbini P. Belli G. Bitelli F. D'amato M. Giorgi E. Galletti E. Stucchi A. Ferrario 《Il Nuovo Cimento D》1990,12(12):1633-1639
Summary In this paper the realization is described of CO2 laser with high energy (≈10J/pulse), long pulses (≈2μs) and narrow bandwidth (≈200 kHz), using suitable discharge device
(Lumonics 602) and cavity configuration (modified self-filtering unstable resonator). The theoretical considerations which
led to these choices are also discussed and the results obtained are shown.
The authors of this paper have agreed to not receive the proofs for correction 相似文献
20.
A novel design of a diode-side-pumped bounce amplifier laser is described that can produce a high-power TEM00 mode and Laguerre–Gaussian (LG) vortex mode operation with high circularity and low astigmatism. The design utilises control
of pump size and bounce angle such that the laser mode experiences substantially circular symmetric gain and spherical thermal
lensing, in a highly compact fundamental mode resonator. In a simple plane–plane Nd:YVO4 laser resonator with no other optical components and total length of just 13.4 cm, highly circularised TEM00 operation is produced at wavelength 1064 nm, with 14.2 W of power and high beam quality M
2<1.05. Stable Q-switched TEM00 operation is demonstrated up to 900 kHz and second harmonic power of 7.2 W at 532 nm is generated with conversion efficiency
up to 64%. Minor modification of the design to exploit the spherical aberration of the thermal lens is shown to allow for
generation of a doughnut-shaped LG vortex mode with average power 16.6 W, maintaining extremely low astigmatism. Q-switched
operation of the vortex mode is accomplished up to 400 kHz. A detailed numerical thermal analysis of the amplifier design
is performed and gives quantitative agreement with experimental results. 相似文献