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Optimization of gallium nitride-based laser diode through transverse modes analysis

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Chinese Optics Letters 2007年第10期5卷 588-590页

作者： Xiaomin Jin 章蓓 Liang Chen 代涛张国义 Electrical Engineering Department California Polytechnic State University San Luis Obispo CA 93407 USA School of Physics and State Key Laboratory for Artificial Microstructures and Mesoscopic Physics Peking University Beijing 100871 RSoft Design Group Inc. 400 Executive Boulevard Suite 100 Ossining NY 10562 USA

We investigate the transverse mode pattern in GaN quantum-well （QW） laser diode （LD） by numerical calculation. We optimize the current GaN LD structure by varying the n-GaN layer thickness. The n-type GaN layer is an important factor to determine the optical mode. Finally, we discuss the lasing performance of the GaN LD based on the transverse optical modes.

关键词： Gallium nitride laser modes Optimization Semiconductor quantum wells

modes competition in a birefringence cavity laser with optical feedback

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Chinese Optics Letters 2005年第12期3卷 694-697页

作者：刘刚张书练徐亭万新军 State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentsTsinghua UniversityBeijing 100084

The modes competition characteristics in birefringence cavity laser are studied in different regions of the gain curve. The mode＇s intensity modulation depth with modes competition is much deeper than that without modes competition. When the average intensities of the two modes are comparable, the intensity modulation depth of either mode reaches its maximum. modes competition can do more contribution to the mode＇s modulation depth than the percentage of light reflected back into the laser cavity does. These characteristics can be used to improve the sensitivity of an optical feedback system. A modes competition factor is introduced to either mode＇s intensity expression which describes the laser intensity more precisely.

关键词： Birefringence Feedback laser modes Modulation

Influence of laser mode on splitting beam illumination effect of Dammann grating

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Chinese Optics Letters 2009年第6期7卷 458-461页

作者：刘丽萍田野孙秀冬赵远张勇靳辰飞 Department of Physics Harbin Institute of Technology

The influences of various laser modes on the splitting beam effect of Dammann grating are studied in theory and by numerical simulation. The results show that fundamental mode laser resembles plane wave while high order mode laser differs from plane wave in the splitting beam effect by Dammann grating. Therefore, the fundamental mode laser is more suitable to be the light source to improve the energy efficiency in far-distance image detecting systems, such as laser image ladar, which use Dammann grating in the ilhlmination svstem.

关键词： Communication channels (information theory) Elastic waves Energy efficiency laser modes Light Light sources Optical beam splitters Optical radar

Analysis of directional emission in square resonator lasers with an output waveguide

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Chinese Optics Letters 2007年第8期5卷 463-465页

作者：赵伟黄永箴 State Key Laboratory on Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences

Square microcavity laser with an output waveguide is proposed and analyzed by the finite-difference time-domain （FDTD） technique. For a square resonator with refractive index of 3.2, side length of 4μm, and output waveguide of 0.4μm width, we have got the quality factors （Q factors） of 6.7 ×10^2 and 7.3 × 10^3 for the fundamental and first-order transverse magnetic （TM） mode near the wavelength of 1.5μm, respectively. The simulated intensity distribution for the first-order TM mode shows that the coupling efficiency in the waveguide reaches 53%. The numerical simulation shows that the first-order transverse modes have fairly high Q factor and high coupling efficiency to the output waveguide. Therefore the square resonator with an output waveguide is a promising candidate to realize single-mode directional emission microcavity lasers.

关键词： Computer simulation Finite difference time domain method laser modes Light emission Refractive index

Transverse-mode controlling of a large-mode-area multimode fiber laser

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Chinese Optics Letters 2007年第9期5卷 524-526页

作者：李立波楼祺洪周军董景星魏运荣何兵李进延 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences FiberHome Telecommunication Tech Co. Ltd.

Coiling technique is used to control the transverse mode of a large-mode-area （LMA） multimode fiber laser. By winding the fiber to a coil with different radius, high-order modes of a multimode fiber laser are suppressed one by one and finally 15.4-W single-transverse-mode output is achieved when the coil radius is 20 mm. It is found that as the coil radius decreases, the beam quality of a multimode fiber laser gets better but the slope efficiency drops for higher-order modes are discriminated. During the experiment, as the coil radius of multimode fiber changes, output characteristic of the laser has been measured. Meanwhile, the mode loss of different modes is calculated theoretically. It is proved that the experimental measured results fit well with the theoretically calculated results.

关键词： Beam quality Calculations laser modes Multimode fibers

Conductively cooled all-solid-state zigzag slab laser

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Chinese Optics Letters 2008年第5期6卷 366-368页

作者：马秀华毕进子侯霞陈卫标 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

A diode pumped, Q-switched Nd：YAG zigzag slab laser is developed using passive conduction cooling. Flat-flat and unstable resonators are adopted in this experiment. The 150-mJ multi-mode and 100-mJ single-mode laser outputs with pulse width of 10 ns are achieved, corresponding to optical efficiencies of 19% and 13%, respectively. The experimental result demonstrates that the laser has the property of compact structure, high efficiency, reliability, and high beam quality. The design of laser has a potential application in space environment.

关键词： laser modes lasers

Normalized intensity correlation function of single-mode laser system driven by colored cross-correlation noises

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Chinese Optics Letters 2008年第4期6卷 288-290页

作者：王兵吴秀清 Department of Physics and Mathematics Anhui University of Science and Technology Huainan 232001

Considering a single-mode laser system with cross-correlated additive colored noise and multiplicative colored noise, we study the effects of correlation among noises on the normalized intensity correlation function C（s）. C（s） is derived by means of the projection operator method. The effects of the selfcorrelation time T1 of the additive colored noise, T2 of the multiplicative colored noise, and the effect of the cross-correlation time TO between the two noises on C（s） are discussed by numerical calculation. For the case of positive correlation （λ 〉 0）, it is found that when a0 〉 0 the normalized intensity correlation function C（s） increases with the increase of T0 or T2, and with value of T0 or T2 becoming larger, C（s） comes to saturation. With increasing the self-correlation time T1 of the additive noise, a minimum and a maximum will appear on curve of C（s） as a0 〉 0. If a0 〈 0, C（s） decreases with the increase of T0, T1, and T2.

关键词： Additive noise Calculations laser modes Mathematical operators Nonlinear optics Optical correlation

Generation of all-fiber femtosecond vortex laser based on NPR mode-locking and mechanical LPG

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Chinese Optics Letters 2018年第11期16卷 5-8页

作者：张志明魏薇唐莉勤杨洁郭杰伟丁镭李乙钢 school of physics nankai universityTianjin 300071 China

An all-fiber femtosecond vortex laser based on common fiber components is constructed. It can produce femtosecond orbital angular momentum modes whose time pulse width is 398 fs. The topological charge of output orbital angular momentum （OAM） modes from this laser can be adjusted among 0, ＋1, and -1 easily while it is also easy to convert between continuous OAM modes and pulse OAM modes.

关键词： Femtosecond lasers laser modes Long period gratings Mode locking Optical angular momentum

Suppression of mode competition in fiber lasers by using a saturable absorber and a fiber ring

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Chinese Optics Letters 2006年第7期4卷 410-412页

作者：杨敬瞿荣辉孙国勇耿建新蔡海文方祖捷 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

An erbium-doped fiber （EDF） laser was configured with a fiber grating, a fiber ring resonator, and a saturable absorber by using un-pumped EDF as mode selection element. The laser showed single mode operation with a narrow linewidth of 5 kHz. The mode selection mechanisms of the un-pumped EDF and the ring resonator are theoretically and experimentally analyzed.

关键词： Erbium laser modes Resonators