Large Relative Raman Shift for Molecules Adsorbed on Metallic Nano-particles

The enhancement of two order-of-magnitudes is observed in surface-enhanced Raman spectroscopy （SERS） of gases （CO, C2H2, C2H4, etc） adsorbed on nitric acid-roughened metal foil. In addition, some Raman lines of gases adsorbed on these active substrates show larger frequency shifts and linewidth broadening, compared with the Raman spectroscopy of free gases. Using the two-oscillator electromagnetic model, we explain this phenomenon. It is related to the large non-regular particles on the active substrate we prepared. It is found that the parameters of the surface-plasmon dispersion, the distance of molecules from the surface and the radius of particles play crucial roles on the relative large Raman shifts.     

15波长输出的布里渊掺铒光纤激光器

多波长布里渊掺铒光纤激光器是一种新型的多波长光纤激光器,其原理是利用受激布里渊增益和掺铒光纤的线性增益,可以在常温下得到波长间隔约为0．08nm(～10GHz)的多波长输出。报道的布里渊掺铒光纤激光器,在布里渊抽运功率为1．7mW、980nm抽运功率为300mW的情况下得到稳定的15个波长(间隔～10GHz)的输出,这种激光器用作光传感器、光谱分析仪以及密集波分复用系统的光源。实验发现,输出波长的个数随着980nm抽运功率的增大而增加。另外,布里渊掺铒光纤激光器的信号功率主要来自于掺铒光纤的增益,而布里渊增益对它的影响不大。     

基于等效衰减矢方法的非均匀光波导色散方程

利用转换矩阵理论和等效衰减矢的概念，以此为根据分析了任意折射率分布平板波导的模式传输特性，导出了意义明确的非均匀平板波导的色散方程的严格的解析解，并指出了ＷＫＢ法的局限性，数值计算的结果表明本文所得公式的结果和严格的数值解非常接近，表明本文所得的公式是严格的。     

MgO:LiNb0.3与LiNb0.3质子交换光波导光学及结构特征的比较

利用退火的质子交换法在MgO:LiNbO.3和LiNbO.3两种材料上制作了光波导，得到了质子交换的扩散特性以及光波导折射率分布的退火规律．通过x射线衍射和OH-红外吸收谱方法研究了 MgO:LiNbO.3和LiNbO.3质子交换光波导的结构特征及其与退火参数的关系，对MgO :LiNbO.3和LiNbO.3光波导光学和结构特征的结果进行了分析和比较． 关键词： 退火质子交换光波导 晶格结构 x射线衍射 红外吸收     

ANALYSIS OF THE GENERAL EFFECTS IN DOUBLE-GRATING DIFFRACTION-INTERFERENCE SYSTEM

Based on the ambiguity function, the optical phenomena of the double-gearing diffraction-interference system are analysed with partially coherent illumination. Different patterns are observed on the observation plane when the optical elements are placed in their proper positions. Detailed discussions on the two extremes of coherence are given. Conclusions could be obtained about the Lau effect, the generalized Lau effect, the incoherent grating-lens imaging, the Talbot effect, the joint-Talbot effect and the generalized joint-Talbot effect. Some special cases are also verified by experiments.     

50 fs输出的全光纤展宽脉冲激光器

利用非线性偏振旋转锁模方法并引进激光谐振腔色散管理,在1550 nm波段上用展宽脉冲全光纤激光器直接产生50 fs无波分裂的高能量脉冲输出.在330 mW的抽运功率下平均输出功率为56.4 mW,单脉冲能量达到1.5 nJ.因为是全光纤结构,激光器的转换效率高达17%.输出光谱平滑,无任何边带存在,激光器处于无波分裂的单脉冲输出状态.     

Generation of the numerator=2 rational harmonic mode-locked pulses in fiber ring lasers

In conventional rational harmonic mode-locking, optical pulse trains with the repetition rate of(pn + 1)fc are generated when the modulation frequency of the in-cavity modulator is set at fm=(n + 1/p)fc, where n and p are both integers, fc is the fundamental cavity frequency. In this paper, we report that rational harmonic mode locking phenomenon takes place in the fiber lasers when the modulation frequency is set at fm =(n + 2/p)fc. The pulse generations are experimentally demonstrated when the numerator of the rational corresponds to 2 in 5th and 7th order rational harmonic mode-locking.     

部分相干光照明下旋转双光栅衍射干涉效应

本文研究部分相干光照明下有旋转夹角的双光栅衍射干涉效应,它是Lau-Talbot-Moire效应的推广。运用模糊函数方法给出系统观察面上一个更为普遍的光强分布数学表达式,并分析讨论一些特殊情况及相应的实验结果。 关键词：     

Generation of the numerator=2 rational harmonic mode-locked pulses in fiber ring lasers

In conventional rational harmonic mode-locking, optical pulse trains with the repetition rate of (pn+1)f_c are generated when the modulation frequency of the in-cavity modulator is set at f_m = (n+1/p)f_c, where n and p are both integers, f_c is the fundamental cavity frequency. In this paper, we report that rational harmonic mode locking phenomenon takes place in the fiber lasers when the modulation frequency is set at f_m =(n+2/p)f_c. The pulse generations are experimentally demonstrated when the numerator of the rational corresponds to 2 in 5th and 7th order rational harmonic mode-locking.     

Generation of domain-wall solitons in an anomalous dispersion fiber ring laser

We report experimental observations performed using a net anomalous dispersion Er-doped fiber ring laser without polarization-selective elements, highlighting the domain-wall solitary pulses generated under the incoherent polarization coupling. By adjusting the pump power and the polarization state appropriately, bright and dark solitons can stably co-exist in the cavity, both centered at 1562.16 nm with a 3-dB spectral width of ～ 0.15 nm and a repetition rate of 3.83 MHz. Moreover, the 0.8 mm long thulium-doped fiber (TDF) facilitated the mode-locking and self-starting of the laser. This is the first demonstration of a laser being used to generate bright and dark solitons synchronously while using TDF as the saturable absorber (SA). Except possessing the all-fiber structure, the laser exhibits good stability, which may have a significant influence on improvement of the pulse-laser design, and may broaden practical applications in optical sensing, optical communication, and soliton multiplexed systems.