利用皮秒脉冲相关技术测量甲酚紫染料吸收恢复时间的研究

本文介绍了利用不同强度皮秒脉冲相关技术测量甲酚紫激光染料吸收恢复时间的原理,实验装置。我们测出甲酚紫染料的吸收恢复时间τ_(21)=163PS,并与国外其它方法测得的数值进行比较,说明结果是可信的。     

隐花菁染料的温度、溶剂、杂质含量对红宝石激光器输出性能影响的理论分析

本文对隐花菁Q开关红宝石器件中染料温度、溶剂、杂质含量对于器件动态输出大小的影响进行了理论分析和数值模拟.结果表明,温度、溶剂、杂质效应的基本原因在于染料激发态的吸收,而其中S_1→S_2的跃迁是主要的.隐花菁的光学漂白程度主要决定于S_1→S_2的吸收饱和,同时也受到三重态的调节.因此,隐花菁调Q红宝石器件热稳定的主要控制因子是溶剂对染料单态激发态的猝灭速率.     

新的适用于钕激光器的超快饱和吸收体

报导了三种1.06微米饱和吸收体，它们的吸收恢复时间比商品9860号染料快。最小的时间常数是2.7微微秒。另外，讨论了用特殊的溶剂缩短吸收的恢复时间。     

一些染料分子中电子单重激发态的无辐射内转换效率与溶剂粘度的关系

本文应用倍频锁模钕玻璃激光器产生脉冲时间为6微微秒、波长530毫微米的激光脉冲,激发3,3′-diethyl-9-methyl thiacarbocyanino Bromide(DMTCB)等染料分子,然后用时间分辨率为微微秒级的条纹相机测定它们的荧光衰变动力学光谱,以研究这些染料分子的荧光寿命与它们的溶剂粘度之间的关系。     

新型菁类化合物溶液的皮秒非线性光学性质

利用带相位物体的非简并泵浦探测方法测量了一种新型菁类化合物溶液在皮秒时域的非线性光学性质。在接近材料线性吸收峰值的532 nm皮秒激光脉冲泵浦下,利用600 nm的皮秒激光脉冲作为探测光,测量了菁染料分子在近共振区的非线性折射动力学响应。结合相关理论,通过数值模拟最终确定了菁染料分子在600 nm波段的光物理参数。实验结果表明:该溶液的非线性光学效应来自于溶质菁染料分子的激发态非线性机制,该材料具备了较大的激发态折射体积,且单重激发态的寿命较短。该化合物具备非线性光学应用潜力。     

Nd3+激光器的新型被动Q开关

本文报导一组Nd3+激光器用的新型醇溶三碳菁染料被动Q开关的研究结果。比较已有的№.3955染料溶液,新型开关在光稳定性、能量效率和弛豫时间等方面都更为优越。指出,这类染料醇溶液开关可保证能量射束在激活区所有截面上具有高度的空间均匀性。使用此种开关的激光微微秒脉宽为6～1毫微秒。     

170微微秒热电探测器

设计和测试了响应时间不到200微微秒的LiTaO_3热电探测器。探测器元件敷有光谱响应平坦的快速热吸收的黑色涂层,并与-13千兆赫带宽Tektronix S-4取样头在阻抗上匹配。用峰值功率在54千瓦时脉冲为100微微秒的Q开关模锁Nd:YAG激光源测量了在1.06微米时的响应。所测量的上升时间为170±30％微微秒,比元件的50微微秒的时间常数长。     

利用染料漂白测量皮秒脉冲宽度和能量

当强光脉冲和吸收染料相互作用时,染料中将产生大量的激发态分子从而降低了基态吸收。如果光脉冲宽度△t_L比荧光寿命τ_F短而且激发态的吸收可以忽略时,染料激发态的分子数就等于吸收光子数。此时,吸收染料介质可作为光子计数器。皮秒光脉冲能量可由测量光脉冲通过染料样品的能量透射率T_E来决定。用这种办法可校正光电探测器的绝对皮秒脉冲能量,当测量了能量透射率和输入峰值光强时,便可用简单公式计算脉冲宽度,因而这为皮秒     

叶绿素d染料分子的实验研究

本文介绍了测量叶绿素d染料的各种参数的实验方法和实验结果。进行了下述四方面的研究。 1.叶绿素d可饱和吸收特性的测定。用叶绿素d Q调制的红宝石激光束,脉宽～10ns,光强范围5×10~5～1×10~8W/cm~2,测量激光束进入染料池前后的衰减与入射光强的关系。即染料透过率与入射光强的关系,通过作图求得叶绿素d在浓度为T=40％(透过率)时的饱和光强I_s≈1×10~7W/cm~2。 2.叶绿素d基态粒子恢复时间的测定。用叶绿素d可饱和吸收体锁模的红宝石激光脉冲系列和一个可变光学延迟装置对叶绿素d和隐花青染料的基态粒子恢复时间进行了     

微微秒克尔光闸原理及应用

微微秒克尔盒光闸开关首先由Duquay和Hansen研制成功。这一装置具有微微秒时间分辨率,广泛应用于微微秒过程的测量上,对于具有微微秒时间尺度的快速物理过程的研究,提供一有力的工具。本文就超快速微微秒克尔光闸的原理、优点和装置的时间分辨率极限,做了详细的评论;并且对于光闸的几种改进措施,例如,阶梯技术,微微秒取样示波器,多通道取样探测器列阵等方面,都做了评述。为了说明清楚起见,文中多次列举实例加以阐述。光闸技术是微微秒光谱学中三大测量技术之一。本文较全面介绍了超快速微微秒光闸技术及其应用的可能性。     

Acceleration of gain recovery in semiconductor optical amplifiersby optical injection near transparency wavelength

By using optical injection near the transparency wavelength of semiconductor optical amplifiers, we show experimentally that both the saturation output power and the gain recovery can be greatly improved. By injecting 80 mW of pump power, we observe a 3-dB increase in saturation output power. For 73 mW of pump power, we find a reduction in gain recovery time from over 200 ps down to below 40 ps, while maintaining 14 dB of fiber-to-fiber gain at 1555-nm wavelength     

Gain recovery of bulk semiconductor optical amplifiers

The gain recovery time of 1.55-μm bulk semiconductor optical amplifiers (SOA's) with lengths from 500 to 1500 μm has been measured with a continuous-wave (CW) probe in the time domain. It is shown to decrease with increasing length down to 60 ps for the longest SOA. This behavior is theoretically explained. A lower limit for the recovery time is observed and explained     

Error-Free 320-Gb/s All-Optical Wavelength Conversion Using a Single Semiconductor Optical Amplifier

We demonstrate error-free wavelength conversion at 320 Gb/s by employing a semiconductor optical amplifier that fully recovers in 56 ps. Error-free operation is achieved without using forward error correction technology. We employ optical filtering to select the blue sideband of the spectrum of the probe light, to utilize fast chirp dynamics introduced by the amplifier, and to overcome the slow gain recovery. This leads to an effective recovery time of less than 1.8 ps for the wavelength converter. The wavelength converter has a simple configuration and is implemented by using fiber-pigtailed components. The concept allows photonic integration     

Passively mode-locked laser diodes with bandgap-wavelength detunedsaturable absorbers

We fabricated monolithic passively mode-locked laser diodes with bandgap-wavelength detuned saturable absorbers using selective growth. The pulsewidth shortened with increasing detuning of the absorber toward shorter wavelengths. For the detuned absorber, the pulsewidth was reduced to 1.2 ps, compared to 2.6 ps for the nondetuned absorber. This originated in broadened mode-locked spectra and reduced absorption recovery time under larger reverse bias voltages for detuned saturable absorbers     

Resonant nonlinear optical properties of GaAs-GaAlAs singlequantum-well waveguide and an integrated asymmetric Mach-Zehnderinterferometer

The resonant refractive and absorptive optical nonlinearities of a GaAs-AlGaAs single quantum-well waveguide are characterized. The recovery time of the absorptive nonlinearity is measured as 125 ps. All-optical operation of an integrated asymmetric Mach-Zehnder interferometer is demonstrated, using intense ~50-ps pulses from a mode-locked Ti:sapphire laser. The device operation is detrimentally affected by thermally induced changes in the refractive index even in a 50 ps timescale     

Passively modelocked 832 nm vertical-external-cavity surface-emitting semiconductor laser producing 15.3 ps pulses at 1.9 GHz repetition rate

A passively modelocked 832 nm vertical-external-cavity surfaceemitting laser, producing pulses of a duration of 15.3 ps at a repetition rate of 1.9 GHz, has been demonstrated. A fast surface-recombination semiconductor saturable absorber mirror, with a bi-temporal absorption recovery characteristic, consisting of fast and slow time constants of 1.5 and 200 ps, respectively, was used to form the pulses.     

Intermodulation distortion in a multiple-quantum-well semiconductor optical amplifier

The measurement of intermodulation distortion (IMD) induced by carrier-density modulation in a multiple-quantum-well (MQW) semiconductor amplifier is reported. The results show that MQW amplifiers have 15 dB less IMD than conventional buried-heterostructure semiconductor amplifiers. The IMD is dependent on the output power of the amplifiers, which confirms that the carrier-density modulation is the dominant nonlinear mechanism in MQW amplifiers. In addition, the results show that, unlike conventional buried-heterostructure amplifiers, MQW amplifiers have at least two time constants (200-250 ps and <10 ps) for the gain recovery process.<>     

基于0.18μm SiGe BiCMOS工艺的高速比较器分析与设计

基于预放大正反馈锁存比较理论,给出了一种8bit 8Gs/s高速比较器的设计.该比较器采用预放大器结构以提高分辨率、加快比较过程,采用主从锁存器降低亚稳态发生概率,采用输出缓冲器改善输出波形、提供测试接口;在HHNEC 0.18μm SiGe BiCMOS工艺下,采用Cadence Spectre进行仿真,结果显示,该比较器精度为4mV,输出摆幅±300mV,锁存时间37ps,过驱动恢复时间22ps,功耗约57mW,表现出良好的性能.     

High-Speed Wavelength Converter Capable of Converting the Same Wavelength Using a Single SOA in a Counterpropagation Scheme

We present a high-speed optical wavelength converter that is capable of converting the data to the same wavelength using a single semiconductor optical amplifier. Error-free wavelength conversion is demonstrated at a bit-rate of 40 Gb/s. The wavelength converter utilizes a counterpropagation scheme assisted by blue-detuned optical filtering technology. The blue-detuned optical filter shortens the recovery time of the wavelength converter, from initial 100 ps down to less than 6 ps, ensuring 40-Gb/s operation. The counterpropagation scheme shows a slow gain saturation time, which becomes a determinant factor for the operating speed of the proposed system. This wavelength converter is constructed by using commercially available fiber pigtailed components. It has a simple configuration and allows photonic integration.      

Operational design on high-speed semiconductor optical amplifier with assist light for application to wavelength converters using cross-phase modulation

Using the newly developed time-dependent transfer matrix method with nonlinear effects, we analyzed the characteristics of cross-phase modulation (XPM), cross-gain modulation and gain recovery time of a semiconductor optical amplifier (SOA) with an assist light injection, which is introduced to speed up the gain recovery of the SOA. Particularly for the application to high-speed wavelength converters using XPM with an interferometer structure where /spl pi/-phase change is required, various parameters such as SOA lengths, wavelengths and powers of injected lights, and their propagation directions are designed via numerical simulation. Discussions concerning the conditions of an SOA structure and the parameters of injected lights for high-speed operation are described to show the potential of fast gain recovery with a response time as low as 25 ps.