新型偏振式CO2波导激光器

为了简化偏振式CO2波导激光器的结构与制造工艺,提出了一种具有新型起偏装置的偏振式CO2波导激光器.该起偏装置就是一矩形波导型阴极.利用位于放电波导口处的矩形波导型阴极对腔内光束的特殊作用,使得只有某一偏振方向的光束才能在光腔内形成稳定的振荡,从而输出稳定的偏振光.从理论上分析了该器件的起偏机理,并通过实验测定了该器件的偏振度指标.该新型器件具有结构与工艺简单、价格低廉等特点,其输出光的线偏振度大于98%.     

Analysis of end-pumped and electrooptically tuned Nd,Ti,MgO:LiNbO3 microchip waveguide lasers

An end-pumped and electrooptically tuned Nd,Ti,MgO:LiNbO₃ microchip waveguide laser is studied by using the self-consistent model and the conformal mapping method. The complex atomic susceptibility is used to describe the laser gain and pump absorption by applying the fast Fourier transform beam propagation method (FFT-BPM) for simulation. Using the conformal mapping method, the index change distributions in the waveguide, caused by the applied electric field, were evaluated. The optimal configuration for the microchip waveguide laser with various cavity lengths was designed. The output performances of the end-pumped and electrooptically tuned Nd,Ti,MgO:LiNbO₃ microchip waveguide lasers were simulated and investigated     

输出实心光束的环波导激光器

本文介绍了一种结构新颖的、具有环形增益介质的环波导CO2激光器。该激光器采用了一个结构简易的光束变换系统,可使出射的环状平行光束转换为实心平行光束。从而大大地拓宽了该激光器的应用范围。     

High-power CO2 laser with coaxial waveguide anddiffusion cooling

A diffusion-cooled CO₂ laser using a coaxial waveguide is analyzed theoretically and experimentally. The resonator used for extracting the laser beam consists of two annular plane mirrors enclosing the two ends of the waveguide. The beam exits through an aperture in one of these annular mirrors. The mirror tilt is shown to provide efficient beam extraction through this aperture. A theoretical resonator model based on the vector modes of propagation in a dielectric coaxial waveguide is presented. Experimental data show the feasibility of coaxial waveguide lasers and their ability to supply beams of high power and quality. Experimental data are discussed with respect to the presented theory     

光纤激光器光场谐振中的附加相移

一、引言 光纤激光器作为一种新型激光器或有源光纤器件为国内外研究者所注目。自80年代以来,从光纤激光器的激活介质到工作形式都有较大的发展。但所研究的激光器一般分为两类:掺杂晶体光纤激光器和掺杂玻璃光纤激光器。谐振腔的形式既有在光纤端面镀反射膜的封闭腔式,也有将光纤置于通常谐振腔的外腔式。光纤激光器与普通激光器的不同点在于:光场在腔内不仅受到反射镜的限制,还受到光纤波导的约束。本文从光纤激光器光场谐振条件出发,提出了光纤激光器中存在光场谐振中的附加相移,并导出了谐振频率与光纤波导参数的关系。     

Cu：KNSBN晶体中光折变波导诱导532nm连续光自泵浦相位共轭

在原来用８ｍＷ连续５３２ｎｍ激光不能产生自泵浦相应共轭的入射角下．先用锁模５３２ｎｍ的ｐｓ激光脉冲在Ｃｕ：ＫＮＳＢＮ晶体中预制一条光折变波导，就很容易用连续５３２ｎｍ激光形成自泵浦相位共轭。预制的光折变波导在一般照明条件下可保存３０ｍｉｎ以上。     

Optical coupling between single-mode semiconductor lasers and strip waveguides

This analysis describes the optimum conditions for coupling a single-mode semiconductor laser to a single-mode strip waveguide, when both the laser and the waveguide have asymmetric optical beam profiles. The outputs are approximated by two Gaussian fields. Two waveguide cases are treated: 1) the case where the two orthogonal waveguide waists are independent and 2) where the ratio of these waists is fixed. The effect on the coupling efficiency of a spherical surface on the waveguide input face is discussed. The results demonstrate the importance of coupling in the laser far-field and indicate the advantage of having relatively large waveguide modes. An intrinsic minimum in the optimum coupling efficiency was found to exist in the near-field for asymmetric laser/waveguide systems. Expressions describing the optimum waveguide waists and the focal length of the lensed waveguide are given for the waveguide parameters that yield the best coupling conditions.     

利用光波导进行准分子激光打孔的加工系统研究

分析了现有准分子激光打孔系统的优缺点,研究了对经过光波导的光束进行掩模打孔的一套加工系统。对光波导的制作进行了分析,并进行了一系列实验,文中给出了试验结果和分析。     

波导HCN激光器输出的EH_(11)模在自由空间中的传播

本文讨论了波导HCN激光器输出的EH_(11)模在自由空间中的传播模式,并与理论进行了比较。在近场,光强的分布明显受到激光器结构上不对称性的影响,其某些特征与Degnan的计算相符;在远场,EH_(11)模的传播近似于高斯光束。因此,对远场激光传播特性的测量是光学系统光路设计的基础。     

A novel SAL-PINSCH quantum-well laser structure for a pinched beamdivergence

Summary form only given. An edge-emitting strained AlGaAs/InGaAs/GaAs quantum-well laser structure is reported. It has a periodic index separate confinement heterostructure (PINSCH) optical confinement layers for a small beam divergence and high output power. Preliminary measurements of AR/HR-coated self-aligned ridge waveguide lasers show a CW output power of up to 350 mW and a 20° transverse beam divergence at a 980-nm lasing wavelength. This low beam divergence results in a high coupling efficiency of 51% into single-mode fibers. The expanded optical field in PINSCH confinement layers significantly pinches the transverse beam divergence and increases the maximum output power     

3kW射频板条CO2激光器抛物面非稳波导腔研究

为了提高传统球面镜腔3kW射频板条CO2激光器光束质量,设计了新型抛物面镜负支非稳-波导混合腔;结合标量光束的瑞利-索末菲衍射理论与特征向量法,研究了大菲涅耳数下镜面类型对非稳波导混合腔光场传输特性的影响;利用矩形波导理论、1维近似分析得出了波导传输损耗及偏振情况。结果表明,将非稳方向输出镜和尾镜改为与光轴交点处曲率半径为R1=951.32mm和R2=1088.68mm的抛物镜面,能够避免尾镜漏光,可有效改善模式鉴别特性;常用波导电极镀膜材料中,镀铝电极内波导方向传输损耗最小,传输光场为x偏振的EH1模。采用电极镀铝的抛物面非稳波导腔能够降低损耗、提升光束质量。     

Compact violet lasers by second-harmonic generation in KTP waveguides

Periodically segmented waveguides were fabricated in flux-grown KTP for quasi-phasematched second-harmonic generation (SHG) of a light beam with a wavelength of 425 nm. Diode-pumped violet laser sources are proposed on the basis of these waveguides. We shall show that a pulsed operation of the pump diode laser at a 940 MHz repetition rate enables the construction of sources with a very compact geometry, which are insensitive to temperature fluctuations. These sources may still be considered as quasi-continuous wave (cw) for applications in high-density optical recording.The most compact type of violet laser source has a size of 1 × 1 × 2 cm³. It contains only the diode pump laser, the KTP waveguide and a miniature lens to couple the pump beam to the waveguide. Time-averaged violet output powers up to 85 μW have been generated for many hours at room temperature without requiring an active temperature control. This output power may be sufficient for reading an optical disc.By optical feedback of a portion of the transmitted pump beam via an external grating it is possible to generate higher violet powers. In this way, the pump laser is forced to operate in a single spectral mode, the wavelength of which can be tuned to coincide with the phase-matching wavelength of the waveguide. This grating-controlled laser system is shown to generate a 425 nm beam with powers up to 0.5 mW. The total length of the device is about 7 cm.     

Mode analysis of a dielectric-loaded Raman-type free-electron laser

The Raman-type free-electron laser consists of a relativistic electron beam contained in a dielectric-induced parallel plate waveguide and an array of permanent magnets for the wiggler. Under the influence of the periodic magnetostatic field, the coupling between the scattered electromagnetic wave of the TE mode (positive-energy wave) and the electron plasma wave of the TM mode (negative-energy wave) is investigated in detail. The following results are obtained. First, when a dielectric sheet is loaded on the waveguide, the maximum growth rate and the oscillation frequency can be greater than those for the vacuum Raman-type free-electron laser. Second, by choosing proper values for the relative permittivity of the dielectric sheet and the ratio of the beam guide, the beam energy can be greatly lowered without degrading the oscillation characteristics. Third, the growth rate decays exponentially with the oscillation frequency kept almost constant as the beam-dielectric gap increases     

Characteristics of Semi-conductor Laser Diode with Nonlinearly Tapered Waveguide

A novel semiconductor laser diode with nonlinearly tapered waveguide is proposed, and analyzed by a finite element beam propagation method (FM-BPM). The results show that the coupling efficiency is increased, and the laser's far field divergence is decreased effectively.     

舰载武器系统激光对瞄方法研究

为了解决目前舰载武器激光对瞄系统存在对瞄成像光斑尺寸较小,以及在动态场景情况下该成像光斑极易偏离出观测视场等缺陷,采用渐变折射率平板波导对成像激光进行1维扩束,激光束在与传播方向垂直平面内的一个方向上进行很好的扩束,而在另一个方向上基本不影响原有光束的传输性能。对改进后的系统进行模拟实验。结果表明,扩束光线具备了较好的对瞄观测效果。     

A Theoretical Analysis of Discrete Reflecting Beam Waveguide with Parabolic Cylindrical Reflectors

A discrete reflecting beam waveguide with parabolic cylindrical reflectors, proposed by M. Kamimura, is theoretically analyzed. Electric field elementary waves on the reflector and the exciting primary electric field from the launcher are represented in the elliptic cylindrical coordinate system, and boundary conditions on the reflector are introduced to derive simultaneous integral equations regarding the reflector current. By solving these integral equations approximately, the integral representation of the secondary electric field in the beam waveguide is obtained, and poles and residues of the integrand are calculated to obtain the propagation constant of the beam waveguide and beam waveguide modes. The beam waveguide mode reflected toward the transmitting side when an obstacle is placed in the beam waveguide is obtained.     

Experimental Realization of Monolithic Diffractive Broad-Area Polymeric Waveguide Dye Lasers

We discuss the first experimental realization of a polymeric waveguide dye laser with intracavity diffractive elements. Due to a special technology used the diffractive phase structures are directly integrated into the waveguide layer. Thus, there is no need for additional external optics or extensive alignment effort. The elements are used to support a Gaussian-like fundamental mode while at the same time suppresses the undesired higher order transverse laser modes. The technology has the potential to be used also for improving the beam quality of semiconductor broad area lasers.     

电磁波泵浦的自由电子激光器

本文研究了电磁波泵浦的自由电子激光器。从跃变磁场结构出来的大半径迴旋环形电子束通过圆柱形波导与圆柱形波导的TE11模入射电磁波相作用。利用电子束的弗拉索夫分布函数理论和三维波导模的波动方程求得在康普顿区域中的散射波色散关系。通过数值分析,讨论了轴向引导磁场,电子束能量,电子迴旋比和电子束环的径向位置等与散射波频率和增长率的关系。     

无吸收模式滤波结构高亮度大功率宽条形半导体激光器

提升宽条形半导体激光器水平方向激射光输出的光束质量,改善宽条形半导体激光器的工作特性,一直是大功率、高亮度宽条形半导体激光器器件工艺研究的难点.基于激射光在无源波导内的衍射原理制备宽条形半导体激光器的模式滤波结构,利用AlxNy绝缘介质薄膜应力使基底半导体材料带隙变化的原理制备无吸收无源波导.将两者结合,设计制备了带有...     

Stability of a light beam in a beam waveguide

Long-distance, high-capacity transmission using a light beam in a beam waveguide is an attractive project for optical communications. However, the transmission of energy in the form of a beam gives rise to a new problem, that is, the stability of a sharp beam. In this paper, the stability problems of a Gaussian beam in a beam waveguide are presented. The deflection and the spot-size variation of a beam in the waveguide with known imperfections, such as transverse displacements of lenses, variation in focal length, and so on, are studied. If the transverse displacements of the lenses are periodic in space, instability of the beam path may occur. The unstable condition is derived. The variation of the spot size at the lenses is obtained in terms of small perturbations of the ideal waveguide. If the incident beam from a laser is not matched to the mode of the waveguide, the spot size at the lenses varies periodically. Statistical results for the models of a waveguide with random lenses, having random transverse position, random spacing, and random focal length, are also given.