Multiwavelength Erbium doped fiber ring lasers

We demonstrate a multiple wavelength laser, employing wavelength dependent cavity losses, with up to four lasing wavelengths on the ITU-grid in the C-band and report on its stability characteristics. The linewidth of each wavelength was estimated to be less than 4 pm and we observed antiphase oscillations around 3 kHz and relaxation oscillations around 25 kHz. The antiphase oscillations in the multiwavelength laser lie on a limit cycle in a relative phase diagram. We present an analytic lumped model to determine the output power and relaxation oscillation frequency of the multiple lasing wavelengths in the Erbium doped fiber. The model is validated against our implementation of a multiwavelength ring laser.     

CuBr激光放电管声波共振现象的研究

为了使有广泛应用的CuBr激光器能稳定和高效运行,针对实验中出现的激光输出功率随放电频率起伏的情况,给出CuBr激光放电管内声波振动的数学模型。该模型选取圆柱形放电管轴为柱坐标轴对波动方程求解,通过数值计算,获得了放电管内声压分布的解析表达式。通过分析放电频率与激光管固有声振动频率的关系,明确了声共振会导致激光介质重新分布,它对激光输出功率有影响,理论计算结果和实验结果完全符合。     

外光注入半导体激光器实现时钟分频

从理论和实验上研究了利用光注入半导体激光器对高重复速率光脉冲产生的周期振荡和时钟分频现象.结果表明，光注入半导体激光器引起的二倍周期振荡是使注入脉冲重复频率分频的直接原因.通过耦合速率方程，数值模拟了半导体激光器在外光注入时输出光的时间序列和功率谱，并且分析了激光腔内各种周期振荡的特征.研究表明，当注入光使半导体激光器出现稳定的二倍周期振荡，且注入光的重复频率为此振荡频率的二倍时，时钟分频即可产生实验中，采用重复频率为6.32GHz的光脉冲注入Fabry-Perot激光器，实现了3.16GHz时钟分频信号 关键词： 周期振荡 时钟分频 光谱侧带 光注入     

Breathing,spiking and chaos in a laser with injected signal

We consider the behavior of a laser driven by an injected cw field detuned from the operating laser frequency. Our analysis covers the entire range of incident power levels from zero to the injection locking threshold. In this domain, the output intensity exhibits regular and chaotic oscillations, a period doubling cascade in reverse order, envelope breathing and spiking.     

Instantaneous frequency measurement applied to semiconductor laser relaxation oscillations

The frequency of relaxation oscillations in the output power of lasers, particularly semiconductor lasers, is an important parameter which can be used to inform other fundamental laser variables, for comparison with expected theory, and to show the effect of external influences, such as optical feedback, by a change in value. Thus, precision measurement of the relaxation frequency is important. Instantaneous frequency measurement algorithms are applied to experimental semiconductor laser relaxation-oscillation signals to determine whether reliable values can be extracted, for an extended range of injection current, as compared to direct measurement and fast Fourier transform techniques. Improvement is achieved but, more importantly, the technique clearly shows when other oscillations, such as those due to packaging, connectorization and power supply, dominate the oscillatory component of the output power, at low injection currents. The work further supports the finding that only mid-range injection currents can be used for reliable precision relaxation oscillation frequency measurement.     

Polarization dynamics of intracavity frequency-doubled Nd:YAG laser

Experimental study of low-frequency dynamics of an intracavity frequency-doubled Nd:YAG laser demonstrates the influence of the interaction of orthogonally polarized modes, participating in frequency doubling (type II phase matching), on the stability of the laser output. At a sufficiently low pump rate and low conversion efficiency, the laser shows stable operation with a low noise level at the frequencies of relaxation oscillations. At a high pump power and/or a high conversion efficiency, the laser emission becomes unstable as a result of Hopf bifurcation at the frequencies of relaxation oscillations that are responsible for the anti-phase polarization dynamics of the laser.     

Intensity dynamics in a waveguide array laser

We consider experimentally and theoretically the optical field dynamics of a five-emitter laser array subject to a ramped injection current. We have achieved experimentally an array that produces a robust oscillatory power output with a nearly constant π phase shift between the oscillations from each waveguide. The output power also decreases linearly as a function of waveguide number. Those behaviors persisted for pump currents varying between 380 and 500 mA with only a slight change in phase. Of note is the fact that the fundamental frequency of oscillation increases with injection current, and higher harmonics are produced above a threshold current of approximately 380 mA. Experimental observations and theoretical predictions are in agreement. A low dimensional model was also developed and the impact of the nonuniform injection current studied. A nonuniform injection current is capable of shifting the bifurcations of the waveguide array providing a valuable method of array tuning without additional gain or structural alterations to the array.     

Multiwavelength fiber ring lasing by use of a semiconductor optical amplifier

A multiwavelength fiber ring laser obtained by use of a semiconductor optical amplifier (SOA) with a simple laser cavity configuration is reported. A Fabry-Perot filter was used in the fiber laser ring cavity to achieve more than 50 simultaneous wavelength lasing oscillations with a frequency separation of 50 GHz. The resulting stable broadband multiwavelength lasing operation was attributed to broadband and flat gain of the SOA, which has a gain flatness of 0.8 dB for more than 20 nm. The laser has a total output power of -3 dBm and a signal-to-spontaneous-noise ratio of 30 dB.     

Observation of a symmetrical lamb dip for a He-Ne laser with a natural mixture of neon isotopes

Lamb dip, which manifests itself in the second mixed derivative of the laser power with respect to the pump and the radiation frequency, is shown to be free from the main asymmetric component that stems from the Ne-22 isotope being present in the active medium. Double differentiation is realized by a synchronous detection of power oscillations of the standing wave at the sum frequency of the reference modulations of the cavity length and the laser pump.     

Dual picosecond dye lasers synchronously pumped by a mode locked cw yag laser

The performance of a novel dual dye laser system synchronously pumped by the frequency doubled output of a mode-locked CW-YAG laser is evaluated in relation to pulsewidth, pulse substructure, pulse spectral width and timing jitter. The behavior of the system is adequately described by a theoretical model which includes the time dependent gain and losses due to frequency bandwidth, cavity length mismatch and output coupler. The jitter is significantly reduced from that obtained with CW gas laser pumping as a result of the shorter pump pulse (50 ns instead of ≈100 ps). A routine operating condition uses 2-plate birefringen filters, 0.8 W pump power at 532 nm, to yield two 2.0 ps pulses having a cross correlation width of 3.8 ps, and 30 mW average power from each laser.     

Relaxation oscillations in an AlGaAs laser studied via the visibility

We have accurately measured the visibility of a Fabry-Pérot type AlGaAs laser as a function of its output power. A damped oscillation in the visibility indicates the presence of relaxation oscillations in the laser. From the data we obtained the output-power dependence of both the relaxation oscillation frequency and damping rate. This allowed us to separately determine the spontaneous lifetime and the dependence of the gain on both carrier density (differential gain) and intensity (nonlinear gain).     

行波管放大器中辐射场的极限环振荡和混沌

以行波管放大器中辐射场的非线性不稳定阈值分析为基础，对辐射场从频率分叉到混沌的演化过程和不同区域这些非线性不稳定态的时间特性和频率特性进行了研究.在“软”非线性区域，辐射场表现为极限环振荡和频率分岔，频谱是离散的且相对于载波频率是不对称的.这种不稳定是阵发性的，适当的调节控制参量，可使器件工作在所需的定态或极限环振荡态上；在“硬”非线性区域，辐射场表现为非周期的随机振荡和频率混沌，频谱连续且频带很宽，场幅值较大的成分集中在接近于零频的低频范围里.这种不稳定是连续性的，不能通过调节参量来消除. 关键词： 行波管 辐射场 分岔 极限环 混沌     

波长可调谐的瓦级连续橙红光激光器

介绍了基于复合腔结构的全固态波长可调谐的连续橙红色激光的输出特性。该复合腔由一个使用周期极化晶体MgO:PPLN的信号光单谐振光参量振荡器和一个LD侧面泵浦Nd:GdVO₄晶体的1 062.9 nm基频光谐振腔构成。s-偏振1 062.9 nm泵浦光抽运单谐振光参量振荡器产生s-偏振信号光腔内独立振荡。通过复合腔结构的优化设计,使独立振荡的p-偏振1 062.9 nm基频光与s-偏振信号光在2个子腔的重叠区内通过Ⅱ类角度匹配KTP晶体的腔内和频过程获得橙红色激光。当MgO:PPLN晶体的调谐温度从30 ℃上升至200 ℃时,s-偏振信号光的中心波长产生红移,导致其与p-偏振1 062.9 nm基频光和频产生的橙红色激光的中心波长从620.2 nm红移至628.9 nm。同时测得中红外波段闲频光的中心波长从3 714.2 nm蓝移至3 438.3 nm。在30 ℃最低设定温度时, 中心波长620.2 nm的橙红色激光和中心波长3 714.2 nm的闲频光最大连续输出功率分别达到2.0 W和2.9 W。     

Genetic drive of a laser

Direct production of laser output pulses with arbitrary shapes can be extended to the high-frequency domain by use of optimal driving of the pump power. Genetic algorithms allow us to design the optimal time evolutions of the pump power to counteract the detrimental effect of relaxation oscillations. The method is demonstrated on a Nd3+:YVO4 laser and allows us to produce, e.g., triangular pulses at rates 20 times faster than for proportional modulation.     

激光二极管端面抽运室温Tm,Ho:YLF连续固体激光器

报道了激光二极管端面抽运Tm，Ho：YLF固体激光器的输出特性.室温下，选用不同透过率的输出耦合镜进行了实验研究，确定了最佳输出耦合镜透过率为2%. 利用小孔扫描的方法，得到了激光远场的光强分布，证明激光为基横模输出，并且给出了热焦距随抽运功率的变化关系.通过在激光谐振腔内插入两个固体Fabry-Perot标准具的方法，获得了2μm激光的单频输出，阈值功率为250mW，在抽运功率为2.8W时，单频输出功率为118mW.此单频激光器可用作激光振荡器和激光放大器的种子源. 关键词： 激光光学 激光二极管 Tm Ho:YLF固体激光器 单频     

注入功率比可调控的双泵浦复合腔501 nm青光激光器

为了探究提高500?nm附近激光高准确度应用的理论和技术依据,本文采用双泵浦源复合腔结合非线性和频变换,实现腔内两种波长基频光无增益竞争,可提高基频光输出功率,同时在复合腔内进行多次非线性频率变换,通过调控基频光注入功率比,使腔内光子数配比达到1:1,从而有效提高了光-光转换效率及和频输出功率.对首次建立的理论模型进行...     

Impact of gain compression on modulation response and dynamic properties of three state lasing InGaAs/GaAs quantum dot lasers

In this paper, we have theoretically studied dynamics of a semiconductor quantum dot (QD) laser for enhancing its small signal and large signal modulation as a function of compression gain. We have considered InGaAs/GaAs QD laser rate equations and solved this equation system numerically. We have revealed that a diminution in compression gain leads to an improvement in frequency bandwidth for this three state lasing system. We also have calculated turn on delay and output power that obviously indicates the effect of compression gain on relaxation oscillations.     

Multiline output from a spin-flip laser

Multiplicity of the output frequency of a spin-flip laser, caused by the simultaneous multiline operation of the CO pump laser, is identified. This multiplicity is shown to arise from a four-wave mixing process for which only a single input threshold intensity exists for oscillation. Experimental data are presented together with a determination of the interdependence of the input and output frequency power ratio.     

Experimental characterization of DFB and FP chaotic lasers with strong incoherent optical feedback

We have experimentally investigated chaotic power oscillations in single-longitudinal mode DFB and multi-longitudinal mode FP lasers as a function of incoherent optical feedback strengths of up to 42%. We have demonstrated the existence of chaos in the output oscillations of both laser types using classical experimental tools such as RF spectrum, standard deviation, and maximum Lyapunov exponent, which all increase with increasing of feedback strength for both in single-longitudinal mode DFB lasers and multi-longitudinal mode FP lasers. It is also shown that power switching among longitudinal modes of multimode FP semiconductor laser is a considerable portion of the chaotic power oscillations for both strong and weak incoherent optical feedback.     

Compact waveguide CO2 laser excited by a RF power supply

The design and performance of radio frequency (RF) excited partial Z-fold waveguide CO2 laser with two channels are exposed. The length of the partial Z-fold channel is 3×460 mm and that of the single channel is 460 mm. The electrodes for the two channels are common and excited by a same RF source. According to our analysis, this kind of structure can greatly improve the laser offset frequency stability. In the experiments, we studied the variation of laser output power with gas pressure for two different channels.The maximum laser output power is about 23 W for the partial Z-fold channel and about 6 W for the single channel.