Characterization and Optimization of Photonic Crystal Optical Power Limiters

In the work, there have been investigated the optical power limiting effects which occur in the nonlinear photonic crys-tals possessing saturable Kerr nonlinearity. The method is proposed which allows exact determination of the parame-ters of the structure as well as the radiation parameters which provide the limiting effect.

Fiber optical parametric oscillator based on photonic crystal fiber pumped with all-normal-dispersion mode-locked Yb:fiber laser

We demonstrate a cost effective, linearly tunable fiber optical parametric oscillator based on a home-made photonic crystal fiber pumped with a mode-locked ytterbium-doped fiber laser, providing linely tuning ranges from 1018 nm to 1038 nm for the idler wavelength and from 1097 nm to 1117 nm for the signal wavelength by tuning the pump wavelength and the cavity length. In order to obtain the desired fiber with a zero dispersion wavelength around 1060 rim, eight sam- ples of photonic crystal fibers with gradually changed structural parameters are fabricated for the reason that it is difficult to accurately customize the structural dimensions during fabrication. We verify the usability of the fabricated fiber experimen- tally via optical parametric generation and conclude a successful procedure of design, fabirication, and verification. A seed source of home-made all-normal-dispersion mode-locked ytterbium-doped fiber laser with 38.57 ps pulsewidth around the 1064 nm wavelength is used to pump the fiber optical parametric oscillator. The wide picosecond pulse pump laser enables a larger walk-off tolerance between the pump light and the oscillating light as well as a longer photonic crystal fiber of 20 m superior to the femtosecond pulse lasers, resulting in a larger parametric amplification and a lower threshold pump power of 15.8 dBm of the fiber optical parametric oscillator.

Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.

High efficiency continuous-wave tunable signal output of an intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%.

High power,widely tunable femtosecond MgO:PPLN optical parametric oscillator

We demonstrate a high power,widely tunable femtosecond MgO-doped periodically poled lithium niobate(MgO:PPLN)optical parametric oscillator(OPO)at 151 MHz,pumped by a Kerr-lens mode-locked Yb:KGW laser.With a maximum pump power of 7 W,the OPO is capable of delivering as high as 2.2 W of the signal centered around 1500 nm with tunable signal spectrum ranges of 1377 nm-1730 nm at an extraction efficiency of 31.4%,which exhibits a long-term passive power stability better than 0.71%rms over 4 h.The maximum idler bandwidths of 185 nm at 3613 nm are obtained across the idler tuning ranges of 2539 nm-4191 nm.By compensating intracavity dispersion,the signal has the shortest pulse duration of 170 fs at 1428 nm.

A 515-nm laser-pumped idler-resonant femtosecond BiB_(3)O_(6) optical parametric oscillator

We report on an idler-resonant femtosecond optical parametrical oscillator(OPO)based on BiB_(3)O_(6)(BiBO)crystal,synchronously pumped by a frequency-doubled,mode-locked Yb:KGW laser at 515 nm.The idler wavelengths of OPO can be tuned from 1100 nm to 1540 nm.At a repetition rate of 75.5 MHz,the OPO generates as much as 400 mW of idler power with 3.1 W of pump power,the corresponding pulse duration is 80 fs,which is 1.04 times of Fourier transform-limited(FTL)pulse duration at 1305 nm.In addition,the OPO exhibits excellent beam quality with M^(2)<1.8 at 1150 nm.To the best of our knowledge,this is the first idler-resonant femtosecond OPO pumped by 515 nm.

PAD Spectrometer Based on Wide Tunable Optical Parametric Oscillator for Noninvasive Medical Diagnostics

The gas analyzer based on optical parametric oscillators (OPO) and laser photo - acoustic spectroscopy is demonstrated. The optical parametric oscillators based on fun – out PPLN and bulk crystal AgGaS2 with a two-pass pumping are developed. Wide tunable OPO is pumped by compact nanosecond Nd: YLF laser. Pulse duration is 5 - 7 ns, maximum pulse energy is 1.5 mJ at a frequency of 100-2000 Hz. OPO lasing threshold is 10 - 16 mJ/cm2 at the spectral range 2.2 - 4 μm for fun – out PPLN OPO and 12 - 20 mJ/cm2 at the spectral range 4 - 7.5 μm for AgGaS2 OPO. Absorption spectra of gaseous mixtures (CH4, C3H8, C2H6, C2H4 and CO2) and human’s breath were studied.

Synthesis, Structure, and Optical Limiting Properties of an Axial Substituted Bis(8-oxide quinoline)zirconium Phthalocyanine

A novel bis(8-oxide quinoline)zironium phthalocyanine [(OQ)2 Zr Pc] with two 8-oxide quinolone anions at the same axial positions has been successfully synthesized and its chemical structure has been assigned by the 1 H NMR, MS and two-dimensional correlation infrared(2D-IR) spectroscopy as well as by single-crystal X-ray structural analysis. It possessed a moderately effective nonlinear absorption coefficient βeff of 6.69×10-14cm/GW at 532 nm in DMF solution, implying it is a promising candidate for nonlinear optical materials.

Cu∶Co∶Mg∶LiNbO_(3)晶体电子结构和光学性质

基于第一性原理研究了LiNbO_(3)晶体及不同Mg浓度下的Cu∶Co∶LiNbO_(3)晶体的电子结构和光学性质。Cu∶LiNbO_(3)和Co∶LiNbO_(3)晶体禁带宽度分别为3.279 eV和3.333 eV,在带隙中出现的杂质能级主要由Cu 3d和Co 3d轨道贡献。在抗光折变Mg离子物质的量浓度达到阈值(约6%)时,光折变掺杂离子在3.069 eV和2.363 eV处表现出较好的光吸收。研究表明,与低浓度Mg离子掺杂晶体相比,Mg离子物质的量浓度达到阈值浓度(约6%)时,存储参量中的衍射效率增强、动态范围增加和灵敏度增高,在双光存储应用中更有优势。

有偏压中心对称光折变晶体中的屏蔽孤子

给出了中心对称光折变晶体中屏蔽孤子的高阶空间电荷场.当高阶项可以忽略时,这个电荷场就变为早前在中心对称光折变晶体中研究的屏蔽孤子的空间电荷场.研究了中心对称光折变晶体中屏蔽孤子的高阶非线性波动方程.在适当的条件下,这个非线性波动方程能够展示明暗空间光孤子.这类晶体不同于非中心对称晶体,其非线性折射率的改变来源于二次电光效应,而不是一般的线性电光效应.应用光束传播的方法,对这些孤子的稳定性进行了讨论.表明在小的微扰下这类孤子是稳定的,不会发生分裂.

石英晶体振荡法监控膜厚研究

给出了石英晶体振荡法监控膜厚的基本原理 ,在相同的工艺条件下分别用光电极值法和石英晶体振荡法监控膜厚 ,对制备的增透膜的反射光谱曲线进行了比较 ,并对石英晶体振荡法的监控结果做了误差分析 结果表明 :石英晶体振荡法不仅膜厚监控精度高 ,而且能监控沉积速率 ,获得稳定的膜层折射率 。

暗光伏孤子的实验研究

在LiNbO3∶Fe晶体中,采用相位掩模对部分空间非相干和相干暗光伏孤子进行了实验研究.实验观察到了部分空间非相干和相干的一维和二维暗光伏孤子,它们的形成来源于光伏效应,是自散焦效应和衍射效应平衡的结果.实验和理论分析表明,暗光伏孤子的形成与光的传输方向,强度梯度与晶体c轴夹角有关;只有在一定的条件下,才能得到稳态的部分空间非相干暗光伏孤子.

温度对光伏光折变晶体中高斯光束演化的影响

为了得到温度对有偏压光伏光折变晶体中高斯光束演化特性的影响结果,基于暗辐射强度对温度的依赖关系,研究了不同温度下高斯光束在光伏光折变晶体中的动态演化。将高斯光束作为入射波,采用数值方法求解波传播方程,当温度是300K时,与晶体匹配的高斯光束可演化成稳定的屏蔽光伏明孤子;当温度变化较大时,高斯光束变得不稳或者发散。在失配的条件下,通过改变晶体的温度能使一不稳定的高斯光束变成一稳定的明孤子波。结果表明,这种温度增加或减少控制下的光伏光折变晶体中高斯光束演化特性的改变有望应用于温控光器件。

有偏压的光伏光折变晶体中的空间灰孤子

正和完善了有偏压的光伏光折变晶体中空间孤子的非线性波动方程的理论 .当光伏效应可忽略时 ,它转化为屏蔽孤子的非线性波动方程 ;当外电场为零时 ,它转化为闭路和开路光伏孤子的非线性波动方程 .证明了有偏压的光伏光折变晶体中存在着空间灰孤子 .它起源于对外电场的非均匀空间屏蔽和光伏效应 .当光伏效应可忽略时 ,它转化为屏蔽灰孤子 ;当外电场为零闭路时 ,它预言了在光伏光折变晶体中存在着光伏灰孤子 .

中红外光参变振荡非线性晶体及器件研究进展

评述了近年中红外光参变振荡器(OPO)的研究进展,主要包括OPO非线性晶体的特性及OPO技术参量与器件系统,给出中红外OPO目前存在的关键问题和今后的发展方向,提出了进一步改善器件性能的可能途径。

Ce∶LiNbO_3晶体的生长及其位相共轭效应

本文报道了 Ce:LiNbO_3晶体的生长及其光折变效应。实验表明,Ce:LiNbO_3晶体具有较高的光灵敏度,优异的位相共轭效应,以及光束在空间分布均匀的特点。通过简并四波混频(DFWM)过程研究了 Ce:LiNbO_3晶体光折变效应的温度效应,并对其机理进行了初步的探讨。

激光为光源的液晶自适应眼底成像系统

建立了一套基于液晶波前校正器的模拟人眼眼底自适应成像系统,该系统采用Shark-Hartman波前探测器进行波面探测,将探测所得波前畸变经过计算处理转化为灰度图,通过电脑施加到LCOS上进行波面校正,通过校正人眼像差的方式来提高系统成像质量。经过校正后,系统波前误差从1.92μm降低到0.048μm,系统分辨率接近70 lp/mm,已经达到该光学系统衍射极限分辨。研究表明,该系统可以满足低阶大像差情况下的模拟人眼视网膜成像要求。

中红外固体激光技术研究进展

波长在3～5mm波段的中红外激光由于处于大气窗口波段,同时又是众多原子及分子的吸收峰,因此在光谱学、医学、通信、遥感、环境监测及红外对抗领域有着广泛而重要的应用前景。目前,固体激光器实现中红外激光输出的途径按照工作介质划分主要包括以Fe:ZnSe晶体为代表的过渡金属掺杂硫族化合物激光器、以MgO:PPLN晶体为代表的光参量振荡器,及以ZGP晶体为代表的光参量放大器3种类型。本文分别介绍它们的技术路线及近年来的最新研究进展,讨论了高能高功率中红外固体激光器的关键技术问题,并对其发展趋势进行了展望。

3～4μm光参量振荡器中双轴晶体计算的新方法

提出了一种光参量振荡器 (OPO)中基于调谐范围中心波长处满足相位匹配条件的KTP晶体计算的新方法 ;该方法通过求出的相位匹配点对有效非线性系数进行数值计算 ,找出有效非线性系数的最大值 ,从而求出该点对应的相位角θ和方位角φ,确定出晶体的切割角 .

基于PPMgLN晶体低阈值宽调谐红外光参量振荡研究

对基于多周期极化掺镁铌酸锂晶体（PPMgLN）的信号光单谐振准相位匹配光学参量振荡器（QPM—OPO）进行了实验研究．以输出波长为1．064μm的声光调Q Nd：YAG固体激光器作为基频泵浦源对周期为29—31．5μm的多周期掺镁（5mol％）铌酸锂极化光栅进行了光学参量振荡温度、周期调谐实验，光参量振荡阈值功率仅为45mW（重复频率1kHz）．通过温度调谐（20～180℃）与周期调谐（29．0—31．0μm）相结合，实现了调谐范围为1445～1685nm的信号光稳定输出。