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1.
Design of optical coupling systems between two-dimensional quasi-stadium laser diodes and single-mode optical fibers 总被引:1,自引:0,他引:1
Optical coupling systems between a two-dimensional quasi-stadium laser diode and single-mode optical fibers using gradient-index
rod lenses are designed for both stable and unstable laser resonators for the first time. A novel numerical approach using
a combination of the extended Fox-Li calculation method and Gaussian beam transformations is proposed. In the case of a stable
laser resonator, two kinds of beam propagation modes appear, namely the axis mode, in which an optical beam propagates along
the cavity axis, and the ring mode, in which optical beams propagate along the diamond-shaped trajectory. The coupling efficiencies
are found to be 54% for the axis mode and 52% for the ring mode. In contrast, an unstable laser resonator exhibits complicated
modes, in which several highly directional beams are emitted from the end mirrors. The total coupling efficiency for these
output beams is calculated to be 9.6%. The 3-dB tolerances for the lens pitch and alignment angles of the gradient-index rod
lenses are also discussed. 相似文献
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We obtained high-quality lowest-loss-mode lasing in quasi-stadium laser diodes having unstable resonators that consisted of two curved end mirrors and two straight sidewall mirrors. The laser diodes were fabricated by applying a reactive ion etching technique to a metal-organic chemical-vapor deposition-grown graded-index separate-confinement heterostructure single-quantum-well GaAs/AlGaAs structure. The electrode contact area of the laser diodes was formed along unstable periodic orbits, along which the optical beams are localized. Highly directional fan-out beams corresponding to the numerically obtained lowest loss mode were emitted from the end mirrors under CW operation at room temperature. 相似文献
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Takehiro Fukushima Koichiro Sakaguchi Masanori Hangyo Yasunori Tokuda 《Optical Review》2013,20(4):293-295
Resonator modes in two-dimensional laser cavities with curved end mirrors filled with a left-handed material were investigated numerically using the extended Fox-Li mode calculation method. The results reveal that the phase profile on the curved end mirrors of a left-handed cavity is inverted relative to that of a cavity filled with a right-handed material. Furthermore, we show that the phase on the end mirrors takes discrete values of zero and ±π under stable resonator conditions, while it varies continuously under unstable resonator conditions. The differences between stable and unstable resonators significantly alter the far-field patterns of the lowest-loss modes. 相似文献
5.
为了提高光束质量、压缩光束发散角,利用现有高功率稳定腔TEA CO2激光器进行了非稳谐振腔的技术改造及激光输出试验,非稳谐振腔采用正分支虚共焦型非稳腔方案。为充分研究谐振腔结构参数及激光振荡模体积对输出能量和光束发散角的影响,共设计加工了包含4种放大率、5种模体积的20组非稳腔腔镜组合。在其它参数都相同的试验条件下,进行了非稳腔镜的单脉冲输出对比试验,得到的最大输出能量为14 J,是原平凹稳定腔的70%,而光束发散角只是原平凹稳定腔的1/4。 相似文献
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为了将虚共焦非稳腔输出光束质量高和角锥棱镜谐振腔具有免调试的优点结合到一起,提出了用球面角锥棱镜构成虚共焦非稳腔的方案。利用已有虚共焦非稳腔钕玻璃激光器,设计加工了一球面角锥棱镜非稳腔钕玻璃激光器。模拟计算了两谐振腔输出光束的模式分布,然后对两钕玻璃激光器进行了实验对比研究。结果表明:实验得到的模式分布与模拟计算结果相吻合,球面角锥棱镜非稳腔钕玻璃激光器与虚共焦非稳腔钕玻璃激光器分别获得了最大2176.9J和2340.6J的能量输出,二者的电光效率与束散基本相同,分别为4.3%,0.30mrad和4.6%,0.26mrad。 相似文献
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We fabricated quasi-stadium laser diodes whose resonators consist of two concentric curved end mirrors and two straight sidewall mirrors. We observed two lasing modes that correspond to different beam propagations along the cavity axis and along a ring trajectory, and different far-field patterns with wide angular separation. The modes can be selected by control of an electrode pattern. We also show that the far-field patterns numerically obtained by the extended Fox-Li mode calculation method are in good agreement with the experimental results. 相似文献
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A. A. Anufrieva L. S. Kuz’minskii A. I. Fedoseev 《Moscow University Physics Bulletin》2007,62(2):128-130
Numerical simulation of self-modulation lasing regimes has been carried out for a CO2 laser with transverse flow of the active medium through an unstable resonator with inhomogeneous internal pumping. Two types of steady-state self-modulation oscillation differing in the feedback mechanism were observed. The type of lasing regime and the conditions of its realization depend both upon the pumping profile and upon the composition and pressure of the working mixture, which makes it generally possible to control temporal characteristics of lasing. 相似文献
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A convex-ARR (Anti-resonant Ring) unstable resonator was introduced in a Cr4+:YAG passively Q-switched Nd:YAG pulsed laser. There are two novel features in this cavity, one is the unstable resonator increasing output energy and improving laser mode; the other is the ARR structure efficiently enhancing the laser stability. A high energy and high stability Q-switched pulse with a single pulse energy of 85.6 mJ, a pulse width of 38 ns and an energy stability of 99.6% was obtained. The experimental results were analyzed well by using the mechanism of transient grating and the properties of the unstable resonator. 相似文献
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In this Letter,a dye-doped cholesteric liquid crystal(DDCLC)-filled hollow glass microsphere is demonstrated to be a resonator with good temperature response.A diglycerol layer is used to wrap the DDCLCs microdroplet to keep it steady and control its orientation.The whispering gallery mode(WGM)lasing and photonic band gap(PBG)lasing caused by two different mechanisms were obtained under the pump of a pulsed laser,and the temperature response of these two kinds of lasing was studied.For the liquid crystal and chiral material used in this Letter,both the WGM lasing and the PBG lasing have a blue shift in wavelength with increasing temperature. 相似文献
13.
D. E. Gakhovich V. P. Kozich A. I. Vodchitz A. S. Grabchicov V. A. Orlovich 《Optical and Quantum Electronics》1990,22(Z1):S57-S60
Single axial mode operation of a YAG: Nd laser based on an unstable resonator with an additional branch and electronic control of the Q-switching has been realized and investigated. The use of the additional branch with a selecting etalon makes it possible to save the output characteristics of the laser with the unstable resonator when going to single axial mode operation. 相似文献
14.
Gakhovich D. E. Kozich V. P. Vodchitz A. I. Grabchicov A. S. Orlovich V. A. 《Optical and Quantum Electronics》1990,22(1):S57-S60
Single axial mode operation of a YAG: Nd laser based on an unstable resonator with an additional branch and electronic control of the Q-switching has been realized and investigated. The use of the additional branch with a selecting etalon makes it possible to save the output characteristics of the laser with the unstable resonator when going to single axial mode operation. 相似文献
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The adjustment effort required for the alignment of laser resonators with arbitrarily shaped end mirrors can be significantly reduced by folding the resonator path half-way between the two end mirrors and by slightly tilting the resonator axis. Thus the resulting resonator consists only of one diffractive mirror and a plane mirror, and the separate alignment of both diffractive end mirrors with respect to each other can be avoided. This principle is demonstrated by a Nd:YAG laser with super-Gaussian output beam. Furthermore, it is shown theoretically that the influence of phase quantization effects on the beam quality can be strongly reduced as a consequence of the tilted resonator axis. 相似文献
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We derive the photocount statistics of the radiation emitted from a chaotic laser resonator in the regime of single-mode lasing. Random spatial variations of the resonator eigenfunctions lead to strong mode-to-mode fluctuations of the laser emission. The distribution of the mean photocount over an ensemble of modes changes qualitatively at the lasing transition, and displays up to three peaks above the lasing threshold. 相似文献
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A. A. Ionin A. A. Kotkov A. K. Kurnosov A. P. Napartovich L. V. Seleznev N. G. Turkin 《Optics Communications》1999,160(4-6):255-260
Spectral properties of radiation of a pulsed electron-beam controlled discharge laser operating on the first-overtone transitions (Δv=2) of CO molecules have been studied both experimentally and theoretically. Various sets of dielectric mirrors with high reflectivity in the wide range of overtone spectrum have been used for the laser resonator. Multiwavelength lasing has been obtained in the wide spectral range of 2.5–4.0 μm. Efficiency of the laser operating on few vibrational transitions within a relatively narrow spectral range comes up to 5% at entirely suppressed fundamental band (Δv=1) lasing. Spectral characteristics of the overtone laser operating on a selected set of vibrational transitions have been analyzed theoretically. A comparison of the experimental and theoretical data has been made. 相似文献
19.
The stability of laser resonators which contain a medium with a gain profile is investigated. Such resonators are unstable when the resonator mirrors are large (infinite aperture approximation), and the gain is lowest on the optical axis and increases with radial distance. It is shown that such resonators have well-defined regions of stability if the mirrors have gaussian reflectivity tapers. 相似文献
20.
We propose the new concept of a switchable multimode microlaser. As a generic, realistic model of a multimode microresonator a system of two coupled defects in a two-dimensional photonic crystal is considered. We demonstrate theoretically that lasing of the cavity into one selected resonator mode can be caused by injecting an appropriate optical pulse at the onset of laser action (injection seeding). Temporal mode-to-mode switching by reseeding the cavity after a short cooldown period is demonstrated by direct numerical solution. A qualitative analytical explanation of the mode switching in terms of the laser bistability is presented. 相似文献