氧化石墨烯被动锁模全正常色散掺镱光纤激光器的研究

发布时间：2018-01-29 15:49

本文关键词： 石墨烯/氧化石墨烯可饱和吸收体掺镱光纤谐波锁模耗散孤子共振多波长耗散孤子　出处：《深圳大学》2015年硕士论文　论文类型：学位论文

【摘要】：脉冲光纤激光器不仅可以产生高峰值功率的光脉冲,而且具有结构紧凑、光束质量好、无需调试、价格便宜等优点。氧化石墨烯作为石墨烯的衍生物,不仅有着可与石墨烯媲美的光学特性,如带宽可调谐、高损伤阈值以及与波长无关的光吸收特性等优点,而且价格低廉、易制取。基于氧化石墨烯可饱和吸收体锁模的脉冲光纤激光器是研究非线性光学现象最有力的平台之一,其现象包括谐波锁模、耗散孤子共振、多波长锁模等,它们在生物成像、光通讯、光学探测、材料处理、光学微加工、光学测量、光传感、光信号处理等方面都有着广泛的应用。本论文以氧化石墨烯被动锁模全正常色散掺镱光纤激光器为研究平台,实验上探究了该激光器的几种不同工作模式,并从理论上解释了这些模式出现的原因。本文的具体工作内容如下:1.介绍了几种锁模光纤激光器的锁模方式及特点,重点讲述了石墨烯及氧化石墨烯作为可饱和吸收体应用于锁模光纤激光器的研究进展。2.分析了石墨烯的能带结构,并阐述了石墨烯的可饱和吸收原理。对氧化石墨烯的光学特性也做了介绍,说明氧化石墨烯也是一种优越的可饱和吸收体,可以与石墨烯相媲美。3.介绍了石墨烯的制作方法。讨论了一种本论文实验所用的渐变薄膜型氧化石墨烯的制作方法,且测量了其线性透过率和可饱和吸收特性。4.基于氧化石墨烯可饱和吸收体搭建了掺镱光纤激光器,不仅实现了重复频率为1.062 MHz的稳定基频皮秒锁模,而且还获得了不同阶数的谐波锁模。通过调节泵浦功率和改变腔内偏振态,可以实现不同阶数的谐波锁模,最高阶数为309阶(328 MHz)。实验中还研究了光谱宽度与谐波锁模阶数的关系。5.基于渐变薄膜型石墨烯可饱和吸收体,在掺镱光纤激光器中观察到了耗散孤子共振现象。通过增加泵浦功率,未分裂的矩形脉冲的宽度能够从3.2 ns增加到7.4 ns,且脉冲振幅保持不变,基频约为1.072 MHz。在最大泵浦功率500 m W下,输出单脉冲能量达到2.43 n J,腔内脉冲能量达到9.7 n J。实验中,还研究了耗散孤子共振脉冲宽度、光谱宽度、单脉冲能量、输出功率随泵浦功率的变化关系。6.通过基于渐变薄膜型氧化石墨烯可饱和吸收体搭建的掺镱光纤激光器,实现了结构简单、紧凑的全光纤化可调谐单波长、可调谐可切换双波长、稳定三波长的耗散孤子锁模掺镱光纤激光器。单波长耗散孤子可调谐的波长宽度为16.4nm(1051.8 nm~1068.2 nm),锁模信噪比大于65 d B。双波长耗散孤子不仅波长范围可调(约10 nm),而且波长间距也是可调的(3.8 nm~13.8 nm),锁模信噪比大于62d B。此外,还研究了多波长耗散孤子形成的机制。
[Abstract]:Pulsed fiber laser not only can produce high peak power optical pulse, but also has the advantages of compact structure, good beam quality, no need of debugging, low price and so on. Graphene oxide is a derivative of graphene. It not only has the advantages of comparable optical properties as graphene, such as tunable bandwidth, high damage threshold and wavelength independent optical absorption, but also low price. Pulse fiber laser based on graphene oxide saturable absorber mode-locking is one of the most powerful platforms to study nonlinear optical phenomena, including harmonic mode-locking, dissipative soliton resonance, multi-wavelength mode-locking and so on. They are used in biological imaging, optical communication, optical detection, material processing, optical microprocessing, optical measurement, optical sensing. Optical signal processing has been widely used in this paper. In this paper, based on graphene oxide passively mode-locked fully normal dispersion doped ytterbium-doped fiber laser as a research platform, several different working modes of the laser have been explored experimentally. The main work of this paper is as follows: 1. The mode and characteristics of several mode-locked fiber lasers are introduced. The progress in the application of graphene and graphene oxide as saturable absorbers in mode-locked fiber lasers is described. 2. The energy band structure of graphene is analyzed. The principle of saturable absorption of graphene is described. The optical properties of graphene oxide are also introduced, which indicates that graphene oxide is also a superior saturable absorber. The preparation method of graphene is introduced, and a method of making graphene oxide film is discussed in this paper. The linear transmittance and saturable absorption.4. Yb-doped fiber laser was built based on graphene oxide saturable absorber. Not only the picosecond mode-locking with a repetition rate of 1.062 MHz is realized, but also the harmonic mode-locking with different order is obtained. The pump power is adjusted and the polarization state in the cavity is changed. Different order harmonic mode-locking can be realized. The relationship between spectral width and harmonic mode-locked order. 5. Based on the gradual film graphene saturable absorber. The dissipative soliton resonance is observed in ytterbium-doped fiber laser. By increasing the pump power, the width of unsplit rectangular pulse can be increased from 3.2 ns to 7.4 ns. The pulse amplitude remains constant, the fundamental frequency is about 1.072 MHz. At the maximum pump power of 500 MW, the output single pulse energy reaches 2.43 nJ. In the experiment, the pulse width, spectral width and single pulse energy of dissipative soliton are also studied. The relationship between output power and pump power. 6. Yb-doped fiber laser with simple structure and compact all-fiber tunable single wavelength is realized by means of ytterbium-doped fiber laser based on gradual thin film graphene oxide saturable absorber. Tunable and switchable dual wavelengths. A dissipative soliton mode-locked ytterbium-doped fiber laser with three stable wavelengths has a tunable wavelength width of 16.4 nm ~ 1051.8 nm~1068.2 ~ (-1). The signal-to-noise ratio (SNR) of mode-locking is greater than 65 dB. The dual wavelength dissipative soliton is not only adjustable in wavelength range (about 10 nm), but also has adjustable wavelength spacing (3. 8 nm~13.8 / nm). The signal-to-noise ratio (SNR) of mode-locking is greater than 62 dB. In addition, the mechanism of multi-wavelength dissipative soliton formation is studied.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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