共查询到20条相似文献,搜索用时 31 毫秒
1.
Hai-tao Huang Jing-liang He Xiu-wei Fan Yan Zhong Hong-liang Chai Yun Wang 《Optics & Laser Technology》2008,40(6):828-831
Q-switched mode locking (QML) has been observed in acousto-optic Q-switched Nd:YVO4 laser that contained no mode-locking components. It was found that QML was easily realized in a long cavity and the modulation depth was observed to increase with increased cavity length. The maximum modulation depth was as high as 90%. This phenomenon is explained by the introduction of gain-related effect in the gain medium. The longitudinal modes at higher frequency, than the central frequency of the gain profile, experience positive guiding, which results in mode locking of these modes. 相似文献
2.
Y. I. Balkarey A. S. Cohen B. B. Elenkrig M. G. Evtikhov O. A. Pashko S. V. Tverdow 《Optical and Quantum Electronics》1991,23(8):1067-1076
The dynamics of optical filaments in broad aperture semiconductor lasers was studied. We use the model where one longitudinal mode is taken into account. The spectrum and the instabilities of lateral modes joined with the above mentioned longitudinal mode were investigated. The structures arise due to instability of various number of lateral modes. On the background of these modes we found a new type of modulation with a frequency depending on the laser aperture width. This frequency is smaller than the electron-photon resonance one. The existence of the modulation was confirmed by experimental investigations of broad aperture laser noise spectra. 相似文献
3.
We show that, when the longitudinal confinement factor in an edge-emitting laser is treated as a dynamic variable, the modulation transfer function has an extra term. This term produces a supplementary photon?Cphoton resonance peak in the modulation response at a frequency corresponding to the frequency separation between longitudinal modes, when these modes are phase-locked long enough (quasi-phase-locked). The photon?Cphoton resonance peak is strongest when two consecutive quasi-phase-locked dominant longitudinal modes have similar longitudinal envelopes and share equally the photon population. 相似文献
4.
基于自旋反转模型, 对双光注入下1550 nm 垂直腔表面发射半导体激光器(1550 nm-VCSEL)的非线性动力学行为进行了理论分析和数值仿真研究. 结果表明: 当一个中心波长位于1550 nm 的副VCSEL(S-VCSEL)同时受到来自两个主VCSELs (M-VCSELs)的光注入时, 在适当的注入条件下, S-VCSEL可处于双光注入锁定态. 此时, S-VCSEL中的两偏振模式均呈现频率为两注入光频率之差的周期性振荡, 输出的光谱仅包含两个主频率部分, 即光谱具有单边带特征. 因此, 基于双光注入下S-VCSEL的周期性振荡可以获得两个相互正交的光毫米波. 通过调节两个M-VCSELs之间的频率差异可使毫米波频率在较大范围内连续可调, 通过调节系统参量可以控制毫米波功率以及调制深度.
关键词:
垂直腔表面发射激光器
双光注入
毫米波
调制深度 相似文献
5.
We present results of modeling and simulation of the harmonic and intermodulation distortions as well as the intensity noise of high-speed semiconductor lasers under two-tone modulation. Multiple quantum-well lasers are considered, which are characterized by large differential gain and a modulation bandwidth of about 25GHz. The study is based on the rate equation model of semiconductor lasers excited by injection current with two sinusoidal tones separated by a radio frequency. The modulated laser signal is modeled in both the time and frequency domains. The time domain characteristics include the fluctuating waveform, while the frequency domain characteristics include the frequency spectrum of the relative intensity noise (RIN), carrier-to-noise ratio, modulation response, harmonic distortion, and the second- and third-order intermodulation distortions (IMD2 and IMD3). The analysis is performed for three frequencies of 5, 15, and 24 GHz, which are, respectively, lower, comparable, and higher than the laser relaxation frequency. The range of the modulation depth covers the regimes of small and large-signal modulation. We show that both RIN and IMD3 of two-modulated laser are minimum when the modulation frequency is 5GHz, and maximum when the modulation frequency is 24 GHz. The second-order harmonic distortion, IMD2, and IMD3 values are larger in the vicinity of relaxation oscillations and increase with the modulation index, especially under large-signal modulation. 相似文献
6.
N. Miura J. Hopwood 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(5):1-10
This paper introduces comprehensive large-signal analyses of modulation dynamics and noise of a chaotic semiconductor laser. The chaos is induced by operating the laser under optical feedback (OFB). Control of the chaotic dynamics and possibility of suppressing the associated noise by sinusoidal modulation are investigated. The studies are based on numerical solutions of a time-delay rate equation model. The deterministic modulation dynamics of the laser are classified into seven regular and irregular dynamic types. Variations of chaotic dynamics and noise with sinusoidal modulation are examined in both time and frequency domains over wide ranges of the modulation depth and frequency. The results showed that chaotic dynamics can be converted into five distinct dynamic types; namely, continuous periodic signal (CPS), continuous periodic signal with relaxation oscillations (CPSRO), periodic pulse (PP), periodic pulse with relaxation oscillations (PPRO) and periodic pulse with period doubling (PPPD). The relative intensity noise (RIN) of these types is characterized when the modulation frequencies are much lower, comparable to, and higher than the resonance frequency. Suppression of RIN to a level 8 dB/Hz higher than the quantum limit was predicted under the CPS type when the modulation frequency is 0.9 times the resonance frequency and the modulation depth is 0.14. 相似文献
7.
S.R. Chinn 《Optics Communications》1979,31(3):359-362
The effect of etalon frequency selectivity on homogeneously broadened mode-locked laser in the limit of low finisse and narrow free spectral range has been calculated. The etalon does not affect the mode-locked pulse width, but modulates the frequency spectrum and causes small secondary pulses. Significant perturbation occurs when the etalon discrimination is one to two orders of magnitude less than the depth of mode-locking modulation. 相似文献
8.
The optical feedback characteristics in a Zeeman-birefringence HeNe laser have been studied systematically when the external cavity varies in a large range. The intensity variations of the two orthogonally polarized lights are observed during the laser cavity tuning in the dual frequency laser. When the external cavity length is an integral multiple of the laser cavity length, either polarized light's intensity modulation depth varies not obviously when the laser works in dual modes conditions or single mode condition. But when the external cavity length is far away from an integral multiple of the laser cavity length and the laser works in different dual modes conditions, polarized light's intensity modulation depth varies obviously. This characteristic can guide us to tune the laser to work in single mode condition to improve the sensitivity of the optical system when the system is used for a large displacement measurement. It can also be used for measuring the position of the target mirror. The theoretical analysis is in good agreement with experimental results. 相似文献
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10.
谐振光学环型腔作为光学陀螺的核心敏感单元,其光学调制谱和与之对应的鉴频曲线的特性成为提高光学陀螺系统检测灵敏度的关键。为了研究光学陀螺的调制和鉴频谱线特性,优化陀螺性能,设计并搭建了实验测试系统,光纤环形谐振腔采用分光比为50∶50、直径17 cm的保偏光纤,总长2.2 m。使用直流高压放大器扫描窄线宽激光器(线宽小于1 kHz)的压电转化模块,扫描频率和电压分别选取20 Hz和1 V,使用模拟比例积分电路进行锁频并反馈给激光器的压电转化模块,使激光器的输出频率跟踪谐振腔实时变化。研究分析了光纤环型谐振腔在两种情况下所对应的透射谱和鉴频曲线:第一种情况为调制电压分别为2 V和4 V,对应调制频率从100 kHz到4 MHz变化;第二种情况为当调制频率为900 kHz,调制电压从2 V到10 V变化。通过实验,得到了不同调制参数下光学陀螺谱线的谐振深度、半高全宽、线性带宽、动态范围、品质因数、标度因数以及对应的锁频精度七种物理量的详细变化情况,并进一步得到了静态测试条件下三种陀螺的最佳调制频率及与之所匹配的调制电压。为进一步研究激光调制对光纤环型谐振腔光谱的影响提供指导。 相似文献
11.
根据对激光器施加的调制信号是否连续,波长调制光谱分为连续和准连续调制激光吸收光谱技术。为了深入的比较研究这两种方案,设计准连续调制谱专用的软件锁相放大器,将准连续调制信号因间断产生的无效信号滤除后,再对吸收信号解调得到二次谐波信号。与连续激光调制谱软件解调的二次谐波信号进行了比较,结果表明,参数相同,准连续调制谱比连续调制谱的信噪比提高5%、检测限降低11.3%。在滤除无效信号后,准连续调制谱也可以解调出标准的二次谐波信号,因此有望用于与气体线型相关的研究中。该工作为选取更加适用的激光调制谱技术,提供了准确依据。 相似文献
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We analyze the mode-competition (MC) phenomenon and the associated noise in multimode semiconductor lasers at microwave modulation. The study is based on the multimode rate-equation model, which takes into account the mechanisms of modal gain suppression. The MC is evaluated by the correlation coefficients between oscillating modes in the laser cavity. We show that an increase in the modulation depth changes the mode coupling from anticorrelation to positive correlation and then to complete coupling, which corresponds to emission of periodic pulses. The frequency spectra of relative intensity noise (RIN) exhibit sharp peaks at the modulation frequency and higher harmonics. The increase in the modulation depth is associated with suppression of the total and modal RIN under high-frequency modulation and with noise enhancement under low-frequency modulation. 相似文献
14.
Monolithic twin-ridge laterally coupled diode lasers emitting at 1.3microm are presented that have a small-signal modulation bandwidth beyond the relaxation oscillation frequency of a single ridge. Spectra and spectrally resolved far fields are presented for three bias conditions: only one ridge lasing, both ridges lasing just above threshold, and both ridges lasing at biases well above threshold. In the first two cases the spectrum has single-peaked longitudinal modes, whereas the third cases shows splitting to in-phase and out-of-phase modes. The splitting frequency of the optical spectrum is measured to be 7.7 GHz. Small-signal modulation measurements reveal a strong resonance at 7.7 GHz, demonstrating an effect of lateral mode locking. As a result of this effect, the twin-ridge laser can be made to have a -3-dB bandwidth beyond that associated with its relaxation oscillation frequency. 相似文献
15.
Topi Uusitalo Heikki Virtanen Paolo Bardella Mihail Dumitrescu 《Optical and Quantum Electronics》2017,49(1):46
The paper explores the possibilities to extend the direct modulation bandwidth in dual-longitudinal-mode distributed feedback lasers by exploiting the photon–photon resonance induced by the interaction of the two modes in the laser cavity. The effects on the direct amplitude modulation and on the direct modulation of the difference frequency between the two modes are analyzed using simulation and experimental results. When the photon–photon resonance, which occurs at the difference frequency between the two modes, is properly placed at a higher frequency than the carrier-photon resonance, the small-signal amplitude modulation (AM) bandwidth of the laser can be significantly increased. However, both simulations and experiments point out that a high small-signal AM bandwidth does not lead to a high large-signal AM bandwidth if the small-signal modulation response has significant variations across the modulation bandwidth. The paper shows that a high large-signal AM bandwidth is obtained when the two modes are significantly unbalanced, whereas a high-bandwidth difference frequency modulation can be best detected when the two modes are balanced and the DC bias is properly chosen. 相似文献
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17.
Injection locking is employed to narrow the spectrum linewidth of individual modes of an active mode-locked laser diode (ML-LD). The multiple modes of the injection-locked ML-LD lie over 3.0 THz with 25-GHz spacing at 30 dB down; their linewidth and stability, ~25 MHz, are nearly the same as those of the master laser. We also demonstrate the accurate frequency measurement of laser diodes stabilized to molecular (H(13)C (15)N ,(13)C(2)H (2)) absorption lines by use of the injection-locked ML-LD. 相似文献
18.
CuBr自锁模激光器的实验研究 总被引:1,自引:1,他引:0
首次报道在纵向放电的CuBr激光器中,通过抑制高阶横模的振荡,同时得到高度稳定完全调制的绿光和黄光自锁模脉冲串,并在实验上研究了高阶横模,泵浦功率和谐振腔腔长对CuBr激光自锁模脉冲串及其纵模频谱的影响. 相似文献
19.
实验观测了短腔染料激光器输出的多纵模激光及其经一级染料放大的激光光谱,比较了光谱特性。在一定情况下,短腔染料激光器的多纵模激光经放大器放大可产生一个至几个新纵模,新纵模与短腔染料激光器输出的纵模有相似的频率间隔、线宽及频率牵引等特征。新纵模产生属于三阶四光子混频(即四波混频)为主导的非线性光学效应。存在频率牵引表明,增益介质中的多波混频存在频率失配,在这一四波混频中光子能量并不守恒 相似文献
20.
The longitudinal linewidth and corresponding relative intensity noise (RIN) of 10- and 40-GHz mode-locked laser diodes are measured for the first time to our knowledge. It is shown that the cavity Q value is a dominant parameter of the linewidth. It is also shown that the linewidth of the individual modes is almost constant. This means that the phase noise of each mode is almost the same in the mode-locked condition. The RIN value is larger for modes that are distant from the center longitudinal mode. This mode dependence is a consequence of the mode partition noise. 相似文献