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High power low-order modes operation of a multimode fiber laser

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Chinese Optics Letters 2007年第4期5卷 221-222页

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

Coiling technique is used to suppress high-order modes of a large mode area （LMA） double clapt multimode fiber. Output powers and beam quality factors M^2 are measured under two different coiling radii. 217 W with M^2 of 2.96 can be obtained for coiling radius of 165 mm and 160 W with M^2 of 1.38 for 52 mm. The corresponding slope efficiencies are 60% and 48%. With smaller coiling radius, the brightness is 3.4 times as high as that of the larger one.

关键词： Beam quality multimode fibers

Acousto-optic Q-switched cladding-pumped ytterbium-doped fiber laser

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Chinese Optics Letters 2007年第7期5卷 415-417页

作者：彭博柳强巩马理闫平 Center for Photonics and Electronics State Key Laboratory of Tribology Department of Precision InstrumentsTsinghua UniversityBeijing 100084

A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.

关键词： multimode fibers Q switched lasers Rare earth additions Spontaneous emission Ytterbium

Generation of tunable multi-wavelength optical short pulses using self-seeded Fabry-Perot laser diode and tilted multimode fiber Bragg grating

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Chinese Optics Letters 2011年第4期9卷 48-51页

作者：蔡同健刘云启张小贝王廷云 Key Lab of Specialty Fiber Optics and Optical Access Network School of Communication and Information EngineeringShanghai University

We experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode （FPLD） with an external cavity formed by a tilted multimode fiber Bragg grating. Dual- and triple-wavelength pulses are obtained and tuned in a flexible manner by changing the temperature of the FPLD. The side mode suppression ratio larger than 25 dB is achieved at different dual- and triple-wavelengths and the typical pulsewidth of the output pulses is ,-70 ps. In the experiment, the wavelength separation can be narrowed to 0.57 nm.

关键词： Fabry Perot interferometers Fiber Bragg gratings Fiber optic components Fiber optic sensors multimode fibers

808-nm fiber coupled module with a CW output power up to 130 W

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Chinese Optics Letters 2007年第8期5卷 466-467页

作者：王晓薇马骁宇方高瞻冯小明刘素平 National Research Center for Optoelectronic Engineering Institute of Semiconductors Chinese Academy of Sciences

A fiber coupled module is fabricated with integrating the emitting light from four laser diode bars into multimode fiber bundle. The continuous wave （CW） output power of the module is about 130 W with a coupling efficiency of around 80%. The output power is very stable after the temperature cycling and vibration test. No apparent power decrease has been observed as the device working continuously for 500 h.

关键词： Light emission multimode fibers Semiconductor lasers

Generation of a hollow laser beam by a multimode fiber

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Chinese Optics Letters 2007年第8期5卷 460-462页

作者：马红玉成华东张文卓刘亮王育竹 Key Laboratory of Quantum Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

A simple method to generate a hollow laser beam by multimode fiber is reported. A dark hollow laser beam is generated from a multimode fiber and the dependence of the output beam profile on the incident angle of laser... 详细信息

关键词： multimode fibers

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

Multi-coupler side-pumped Yb-doped double-clad fiber laser

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Chinese Optics Letters 2004年第5期2卷 285-287页

作者：欧攀闫平巩马理韦文楼 Center for Photonics and Electronics Department of Precision Instruments Tsinghua University Beijing 100084

The side-coupler of angle polished method, using angle-polished multimode fiber and optical adhesive, is used to efficiently pump an Yb-doped double-clad fiber laser. The maximum coupling efficiency of 78.6% is achieved by the side-coupler for a multimode fiber with a circular core of 200μm and a double-clad fiber with a 350/400μm D-shaped inner cladding. While laser diodes (LDs) with three side-couplers are simultaneously used as pump sources, maximum output power of 1.38 W and slope efficiency of 48.9% are demonstrated in the fiber laser system.

关键词： multimode fibers Optical fiber coupling Pumping (laser) Semiconductor lasers

Observation of a fused dual-fiber sensor head tips by SEM

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Chinese Optics Letters 2006年第1期4卷 8-10页

作者：王晓旭林钧岫王德和 Department of Physics Dalian University of TechnologyDalian 116024

The shape and microstructure of the fiber-optic liquid-level sensor head. which was made of two fusion- spliced multimode optical fibers, were experimentally studied by using scanning electron microscope （SEM） technology in order to optimize the performance characteristic of the fiber sensor head. The parabolic profile of the sensor head was found to be better and having length-width ratio from 1.2：1 to 1.3：1. Some other useful possibilities were proposed.

关键词： Light modulation Liquid level indicators Microstructure multimode fibers Refractive index Scanning electron microscopy

Two-dimensional overlapping-image multimode interference couplers

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Chinese Optics Letters 2005年第3期3卷 154-155页

作者：孙一翎江晓清唐奕王明华 College of Engineering and Technology Department of Information and Electronic Engineering

The overlapping-imaging effect of one-dimensional (1D) multimode interference (MMI) coupler is widened to study the two-dimensional (2D) MMI coupler. 2D overlapping-image MMI couplers permit uniform and nonuniform 2D power splitting. Analytical formulas are derived for the intensities and phases of the overlapping-images at the end of MMI section. The overlapping-imaging properties in 2D MMI couplers are also concluded. And the guided-mode propagation analysis method is used to confirm the analytical results.

关键词： Image processing multimode fibers One dimensional Two dimensional Wave interference