Long wavelength VCSELs at 1300 nm have been developed to serve 10-Gigabit enterprise networks over FDDI grade multimode fibers up to 300 m in distance. The long wavelength VCSELs operate CW at temperatures over 100 °C. They are ideal low cost alternatives to DFB lasers for transceivers and transponders compatible with IEEE 10GBASE-LX4 or 10GBASE-LRM standards over multimode fibers.

A tunable ytterbium doped double cladding fiber laser with high efficiency has been investigated. The output power of the fiber laser was about 440 mW using 1 W 915 nm LD pumping and the slope efficiency was about 80%. The M2 factor of the output beam in both directions were 1.06 and 1.04, respectively. The output wavelength can be tuned from 1070 nm-1150 nm while using a grating at output coupler.

A stable ns pulse has been generated from a self mode locking Yb doped fiber laser using Yb doped fiber Bragg grating with 15 dB reflectivity as a reflector, and the pulse width is less than 5 ns. The average output power about 3 mW and repetition rate of 25 MHz are obtained under stable mode locking condition. The laser threshold is 18 mW and energy convert efficiency is 5%. The cause and characteristics of the self mode locking fiber laser have been also investigated.

由光纤回路镜组成的新型串级光纤拉曼激光器,用1064 nm作为抽运源,光纤拉曼激光运转于第三级斯托克斯串级拉曼波段,输出波长为1240 nm.在光纤回路镜的性能和光纤参数还不够完善的条件下,1240 nm输出功率为300 mW,光光转换效率约为25%.

提出了一种新的衡量散射体系中散射颗粒消光能力、散射能力和吸收能力的方法并与传统方法进行了比较.在此基础上,讨论了散射颗粒折射率和颗粒大小对其散射能力的影响.运用此方法可以为各种散射体系,尤其是强散射体系选择恰当的散射颗粒,其结果优于用传统方法所得的结果.

We report the scatterer concentration-dependent behaviour of laser action in high-gain scattering media. A modified model of a random laser is proposed to explain the experimental results in good agreement. We may use this modified model to design and optimize the random laser system. A further detailed model is needed to quantitatively analyse the far-field distribution of random laser action.

Measurements on the third order optical nonlinearities of the conjugated polymeric cast film of PPQ (polyphenylquinoxalines) were performed based on the so called Z-scan method using a frequency doubled mode-locked Nd:YAG laser with low repetition rate. The nonlinear absorptive coefficient, β=0.59 cm/MW, was obtained for PPQ, in addition, the measured nonlinear refractive index coefficient γ=2.4×10 -12cm 2/W was in a good agreement with the previously reported value.

自行设计和拉制的掺镱双包层光纤采用内外包层都是石英玻璃的结构 ,能与常规光纤兼容连接 .在泵浦光功率受到限制的条件下 ,掺镱双包层光纤的输出功率达到 90 m W,斜效率为 2 8% .对掺镱双包层光纤激光器的有关特性进行了研究和讨论 .

Measurements on the third order optical nonlinearities of the conjugated polymeric cast film of PPQ (polyphenylquinoxalines) were performed at 532 nm wavelength by using a frequency doubled mode-locked Nd:YAG laser with 10 Hz repetition rate. High two-photon absorption coefficient was obtained. The measured nonlinear refractive index coefficient is in agreement with the previous reported value. It was attributed to a pure electronic response for the optical nonlinearity.

The polyphenylquinoxaline (PPQ) planar waveguide is fabricated. The nonlinear characteristics of this waveguide are studied. The notable broadening in laser spectrum due to self-phase-modulation is observed by using femtosecond laser pulse. It shows that this new kind of organic polymer waveguide has strong nonlinear effect.

Femtosecond laser pulse is used to study the fringe variation on the spectrum of pulse due to F-P effect in PPQ organic polymer film. By changing the pulse peak intensity, the fringe variation is observed evidently, while fringe variation is not observed at broadened pulse duration and the same average power. It shows that the thermal effect is no greater contribution to the refractivity, the main reason that leads to fringe variation on the spectrum can be attributed to the nonlinear refractive index change of PPQ film due to high pulse peak intensity.

Integration calculations for the absorption spectrum of PPQ polymeric cast film, by means of the Kramers-Kronig relation, were performed for a serial number of wavelengths. An existence of an region of anomalous group-velocity dispersion (GVD) span near (550-700) nm band was evidently indicated. The dispersion parameter β2 is relatively small, β2 <1.2 ps2/m, so that a dispersion neglected nonlinear Schordinger equation was used to described the propagating behavior of femtosecond colliding pulse mode-locking (CPM) laser pulses in planar optical waveguide of PPQ film, and consequently, the obtained nonlinear refractive index coefficient n2 was in good agreement with the reported value.

In the past two decades, third-order nonlinear optical properties of organic and polymeric materials have attracted considerable attention to realize all-optical signal processing devices.1,2 Especially, the large off-resonance third-order optical nonlinearities of conjugated organic polymers with delocalized π--electron systems, such as polydiacetylenes3,4, are considered to be potential candidates. Although conjugated polymer is reported to have large χ(3) and fast response time, many of them are highly intractable materials that are difficult to process to form the low-loss waveguide structures required for their application5. Recently, many techniques for fabricating low-loss planar waveguides in thin films of solution processible conjugated polymer have been developed7,8 besides third-order nonlinear optical polymers that exhibit low absorption have been reported6 Furthermore, numerous different schemes which aim is all-optical switching and all-optical logic operations have been suggested for practical devices. They are included in nonlinear prism and grating couplers and nonlinear directional couplers9,10, such as two-channel nonlinear directional couplers, nonlinear Mach-Zehnder interferometers, nonlinear distributed-feedback grating reflectors and adiabatic polymer-glass-waveguide all-optical switch11,12. However, though the prism coupler has attracted partially significant attention both theoretically13 and experimentally14, as so far we know the nonlinear prism coupling to organic polymer waveguide has only been demonstrated in single beam experiments on intense-dependent nonlinear effects15.

测量了Ｃｒ４＋ＹＡＧ、Ｃｒ４＋Ｍｇ２ＳｉＯ４晶体在室温和液氮温度下的荧光光谱、吸收光谱和激发态寿命，讨论了温度变化时，两种晶体中Ｃｒ４＋近红外辐射积分强度变化与激发态寿命变化的关系，得出结论：在７７Ｋ～３００Ｋ范围内，Ｃｒ４＋的３Ｔ２能级荧光辐射截面本身受温度影响不大，Ｃｒ４＋辐射荧光的变化，主要是由无辐射驰豫速率随温度变化而引起的

> A time-resolved cross-phase modulation method combined with a modified nonlinear Schrodinger equation is used to study the effects of nonlinear response time on the propagation of ultrashort pulses in nonlinear dispersion media. Evolution of cross-phase modulation spectrum with the different time delay between the probe pulse and pump pulse is simulated using split-step Fourier method. It is shown that both normal self-frequency-shift-red-shift and abnormal self-frequency-shift-blue-shift can occur in the frequency domain for the probe pulse, and a satisfactory theoretical interpretation is given.

The emission spectra, absorption spectra and the excited state life time of Cr4+: YAG and Cr4+: Mg2 SiO4 crystals were measured at room temperature and liquid nitrogen temperature respectively. The variation of the integral fluorescent intensities at the two different temperatures was obtained. Considering it with the variation of the excited state life time, a conclusion is drawn that in the range of 77K to 300K, the influence of temperature on the emission cross section of Cr4+ is relatively small. The change of the fluorescent intensity is mainly because of the change of non-emissive relaxation rate with temperature.

Organic polymers are attractive nonlinear materials because of their both large nonlinear coefficient and ultrafast response time. By use of the modified nonlinear Schrodinger equation, the effect of delayed nonlinear response time. as well as second-and third-order dispersion, had been investigated numerically on the propagation of femtosecond optical pulse. It has been shown that the red shift due to the delayed nonlinear response time in frequency domain increases with the increasing of delayed nonlinear response time primarily, and then decreases when the delayed nonlinear response time exceeds a certain value.

We present research on nonether polyphenylquinoxaline film waveguides, and a scheme for an all-optical switching operation of waveguides is suggested. We use the m-line spectroscopy technique to characterize the guiding modes in the waveguide, and the switching phenomenon is observed with two-wavelength nonlinear prism coupling. The measured response time of the switching signal is less than 10(-9) s.

We study the chirp characteristics of femtosecond laser pulse propagating in conjugated polymer with larger nonlinear dispersion effect by means of theoretical and simulated methods. From the chirp characteristics of femtosecond laser pulse, the explanation for effective spectrum broadening and self-frequency-shift is given.