Design and Fabrication of Integrated-Optic Disk Pickup on LiNbO_3 Substrate

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｒｅｈａｓｂｅｅｎｍｕｃｈｒｅｓｅａｒｃｈａｎｄｄｅｖｅｌｏｐｍｅｎｔｉｎｔｅｒｅｓｔｉｎｏｐｔｉｃａｌｄｉｓｋｍｅｍｏｒｙｓｙｓｔｅｍｓｂｅｃａｕｓｅｏｆｔｈｅｈｉｇｈｃａｐａｃｉｔｙｓｔｏｒａｇｅ .Ｉｎｅａｒｌｙ ｐａｐｅｒｓ[1 ,2 ] ,ｉｎｔｅｇｒａｔｅｄ ｏｐｔｉｃａｎｄ ｍａｇｎｅｔｏｏｐｔｉｃｄｉｓｋｐｉｃｋｕｐｈｅａｄｓｈａｖｅｂｅｅｎｄｅｍｏｎｓｔｒａｔｅｄ .Ｔｈｅｏｐｔｉｃａｌｄｉｓｋｐｉｃｋｕｐｈｅａｄｉｓｃｏｎｓｔｒｕｃｔｅｄｂｙｉｎｔｅｇｒ…     

Efficient 340-nm light generation by a ridge-type waveguide in a first-order periodically poled MgO:LiNbO3

Quasi-phase-matched (QPM) UV second-harmonic generation (SHG) in a periodically poled MgO:LiNbO3 waveguide is presented. A ridge-type waveguide with high nonlinearity and strong resistance to photorefractive damage was achieved by use of an ultraprecision machining technique. By use of this waveguide in 1.4-microm periodically poled MgO:LiNbO3, a first-order QPM SHG device for 340-nm UV radiation was demonstrated. In a single-pass configuration, continuous-wave 22.4-mW UV light was generated for a fundamental power of 81 mW, corresponding to a normalized conversion efficiency of 340%/W.     

466 mW green light generation using annealed proton-exchanged periodically poled MgO: LiNbO3 ridge waveguides

We report high-power efficient green light generation by frequency doubling from a periodically poled MgO doped LiNbO(3) ridge waveguide. The ridge waveguide is fabricated by the annealed proton-exchanging and precise diamond blade dicing techniques. The ridge structure exhibits a surface roughness of only 3.7 nm, and near-90° vertical sidewall. The total insertion loss of an 8.5 μm wide and 1.4 cm long uncoated waveguide is 3.0 dB under direct fiber coupling. 466 mW of continuous-wave green light with an optical-to-optical conversion efficiency of 69.7% is obtained. To the best of our knowledge, this is the highest green light output power reached to date using a ridge-type LiNbO(3) waveguide device. Phase-matching temperature shift, tuning curve distortion, and waveguide loss increase are observed under high power operation. Our analysis shows that the photorefractive effect and the green induced infrared absorption are responsible for the observed phenomena, which becomes prominent under several megawatt per square centimeter power density.     

Nondestructive measurement of loss performance in channel waveguide devices with phase modulator

A novel method using a phase modulator is proposed for the nondestructive measurement of propagation loss in a channel waveguide. The phase modulator was fabricated on a Ti-diffused LiNbO3 crystal. Tuning the effective optical length of a waveguide by application of an electrical field on the phase modulator, the contrast of the resultant Fabry-Perot resonator in a channel waveguide device can be measured. The associated propagation attenuation coefficients are determined from the experimental results. Coordination of the phase modulator with an optical channel waveguide device not only allows measurement of the bending loss, but improvement in the relative intensity noise owing to the reduction of the reflected power.     

900-nm Nd:Ti:LiNbO(3) waveguide laser

We report what is to our knowledge the first laser operation of Nd(3+) -doped LiNbO(3) near 900 nm. An absorbed power threshold of 26 mW was obtained when the device was pumped at 814 nm. The design of the waveguide geometry to favor laser operation at this wavelength is demonstrated.     

Unequally spaced multiple mid-infrared wavelength generation using an engineered quasi-phase-matching device

We propose a novel quasi-phase-matched (QPM) device that can generate unequally spaced multiple wavelengths. Unequally spaced multiple QPM peaks can be obtained by employing the optimized phase modulation of a periodic domain structure. We fabricated a LiNbO3 waveguide device for 3.2-3.4 microm band difference frequency generation based on the design. Using the multiple mid-infrared outputs, we demonstrate the detection of multiple hydrocarbon gases, namely, methane, ethylene, and ethane.     

Second-harmonic generation with a high-index-clad waveguide

Theoretical and experimental analyses of second-harmonic generation (SHG) with a high-index-clad waveguide are reported. It was found that confinement of the propagation modes and the overlap between the fields of fundamental and second-harmonic waves could be increased in this waveguide. This structure was achieved in an x-cut MgO:LiNbO (3) quasi-phase-matched (QPM) waveguide by use of Nb(2)O(5) as a cladding layer. With the QPM SHG device, harmonic blue light of 5.5 mW at the 434-nm wavelength was generated with a normalized conversion efficiency of 1200%/W cm(2).     

集成光学平板光盘读出头研制

采用集成光学方法,将非球面消球差双凸波导透镜、双光栅会聚光波导透镜、光波导转向棱镜单片集成在铌酸锂基底上构成光学平板光盘读出头.集成光学平板光盘读出头克服了微透镜光盘读出头体积大、组装复杂的不足,实现了光盘读出头的集成化,提高了系统的可靠性.光斑理论值0.475 μm,实测值0.67 μm.     

小型铌酸锂多功能集成光学器件

为满足小型光纤陀螺对光学器件小体积的要求,对铌酸锂多功能集成光学小型化器件的结构做了分析和优化设计。采用BPM软件分析了Y形分支波导的S形波导损耗与弯曲长度及折射率差的关系。通过调整退火质子交换的工艺参数,增加了波导对光的束缚能力;降低了小型化芯片上S形波导的弯曲损耗;去掉了原有Y形波导的输出端直波导,直接由S形弯曲波导引至输出端,在更短的芯片上得到了更长的弯曲过渡区。设计制作的芯片长度由常规的20 mm减至12.5 mm,封装后的器件长度减小到20 mm,为目前同类常规器件尺寸的2/3。设计制作的器件插入损耗典型值小于2.5 dB,全温损耗变化量小于0.2 dB。     

Highly efficient single-photon detection at communication wavelengths by use of upconversion in reverse-proton-exchanged periodically poled LiNbO3 waveguides

Conventional single-photon detectors at communication wavelengths suffer from low quantum efficiencies and large dark counts. We present a single-photon detection system, operating at communication wavelengths, based on guided-wave frequency upconversion in a nonlinear crystal with an overall system detection efficiency (upconversion + detection) exceeding 46% at 1.56 microm. This system consists of a fiber-pigtailed reverse-proton-exchanged periodically poled LiNbO3 waveguide device in conjunction with a silicon-based single-photon counting module.     

Second-harmonic generation in a direct-bonded periodically poled LiNbO(3) buried waveguide

We report the fabrication of a 12-mum -thick periodically poled LiNbO(3) planar waveguide buried in LiTaO(3) by direct bonding of precision-polished surfaces. Frequency doubling of the 1064-nm output of a cw diode-pumped Nd:YAG laser was performed in a 5.5-mm-long device with a 6.50-mum -period grating at an elevated temperature of 174 degrees C. The resultant green second-harmonic output exhibited fundamental-spatial-mode characteristics at a 4.3%W(-1) conversion efficiency.     

LiNbO(3) platforms for optical fiber alignment

A technique for incorporating a groove into a LiNbO(3) substrate is described. Both V grooves for fiber alignment and vertical grooves for waveguide end-face formation can be fabricated with this technique. The proposed fabrication method is based on an excimer-laser ablation and a high-speed rotation saw cut for LiNbO(3) . The former process provides a variety of cross-sectional groove shapes by changing the ablation mask shape of LiNbO(3) , and the latter provides an optical-quality cutting face. The proposed fabrication method is simple and provides low-cost optical platforms not only for LiNbO(3) but also for glasses, polymers, and semiconductors.     

Ti∶LiNbO_3二维渐变折射率光波导传播常数的计算

从Ti∶LiNbO3波导截面折射率分布的特点出发，得出一套计算传播常数简单而精确的方法。文中对该法进行了分析，并应用该方法计算了钛扩散波导的色散关系。该方法为钛扩散光波导集成光学器件的设计提供了一种较可靠的理论手段。     

掺铒铌酸锂波导放大器增益特性的理论分析

对掺铒铌酸锂（Ｅｒ３＋：ＬｉＮｂＯ３）波导放大器在１４８０ｎｍ泵浦光单向和双向泵浦下的增益特性作了计算机模拟理论分析,采用二能级速率方程,忽略ＥＳＡ的影响,应用数值法得出方程解,优化设计放大器参数     

一种质子交换铌酸锂波导与保偏尾纤对轴方法

提出了一种用宽谱光源及偏光干涉效应为质子交换铌酸锂波导与其保偏尾纤的对轴方法.将宽谱光源与待对轴的保偏光纤相熔接,当宽谱光通过保偏光纤和质子交换铌酸锂波导后,由于偏光干涉效应,相干函数上新增不同的次峰.利用各次峰的位置和幅值信息,可解算出质子交换铌酸锂波导与其保偏尾纤的对轴角度,将解算出的角度作为反馈控制信号即可实现在线对轴.     

单模光纤与Ti:LiNbO3单模平面光波导端面激励耦合的研究

本文报导一个单模光纤与单模Ti扩散LiNbO3光波导的端面耦合及固定连接实验研究.利用电弧烧熔法在单模光纤端面上制成了微透镜,改善了模场匹配程度,采用二维硅V形糟,提高了光纤与波导的对准精度。     

Guided-wave second-harmonic generation in a LiNbO3 nonlinear photonic crystal

We demonstrate twin-beam second-harmonic generation from telecommunications wavelengths in an optimized buried reverse proton exchanged planar waveguide made in 2D hexagonally poled LiNbO3. Experiments carried out with a nanosecond narrow-bandwidth, high-power fiber source thoroughly explored the response of the nonlinear photonic crystal device in terms of its power, wavelength, and angle tunability.     

Cr: LiNbO_3 Planar Waveguide

Ｃｒ：ＬｉＮｂＯ_３ＰｌａｎａｒＷａｖｅｇｕｉｄｅ￥ＺＨＵＳｈｅｎｇｘｉａｎｇ；ＪＩＡＮＧＸｕｙａｎｇ；ＱＩＵＹｕａｎｗｕ（ＰｏｈｌＩｎｓｔｉｔｕｔｅ，ＴｏｎｇｊｉＵｎｉｖｅｒｓｉｔｙ，ｓｈａｎｇｈａｉ２０００９２）ＷＵＹｏｎｇｊｉａｎ；ＸＵＺｈｅｎ?..     

Analysis of output statistics of single and double pass Er-doped LiNbO3 waveguide amplifiers

Based on the photon statistics master equation of the linear amplifier, this paper presents a theoretical evaluation of the following important amplifier parameters: the output mean photon number, the standard deviation, the Fano factor, the statistical fluctuation and the spontaneous emission factor for single and double pass configurations and for forward and backward pumping schemes in the case of an Er3+-doped LiNbO3 waveguide amplifier. The simulations were performed using the small gain approximation and the above-mentioned device characteristics versus pump powers, waveguide length and signal wavelength are evaluated. This revised version was published online in November 2006 with corrections to the Cover Date.     

LiNbO3:Fe晶体中光写入平面光波导的导光特性研究

从光折变效应的单中心模型和载流子的光伏迁移机理出发给出了高斯片光在LiNbO3:Fe晶 体中导致的折射率变化分布的解析表达式.利用片光以“三明治”辐照方式在LiNbO3:Fe晶 体中写入了平面光波导结构.用切片干涉法测量了波导区的折射率分布，并对波导进行了简 单的导光测试.根据射线方程以及波导的折射率分布对光写入波导的导光特性进行了模拟计 算分析.研究结果表明，在LiNbO3:Fe晶体中光写入光波导是可行的. 关键词： LiNbO3:Fe晶体 光辐照法 平面光波导 导光特性 高斯片光