Metal island films for write-once multiwavelength three-dimensionaloptical disks

Metal island films are proposed and investigated as optical data storage media for write-once multiwavelength three-dimensional disks. The basic operation has been experimentally confirmed using aluminium-silver compound metal island films for 490 nm and silver-gold compound metal island films for 810 nm. Compact write-once multiwavelength three-dimensional disks for durable long-term data storage could be realised by using metal island films with high reflectance near the resonance wavelength, and large reflectance change by heating     

Group delay measurements of optical components near 800 nm

Phase-locked interferometry was used to measure the group delay of several optical components in the spectral region 700-850 nm. The dispersive and absorptive properties of several different types of linear filters were measured. Measurements of the absorption and dispersion of several linear, causal optical filters show that a generalized Kramers-Kronig relation does not exist for many commonly used filters. This result emphasizes the importance of making direct measurements of the dispersive properties of filters, since the dispersion of a linear filter cannot always be determined from a measurement of its absorption. Data are presented for a birefringent filter, dielectric mirror, Gires-Tournois interferometer, and titanium-doped sapphire     

Cascadable optical inversion using 1550 nm VCSEL

A novel, cascadable optical inverter is demonstrated up to 2.5 Gbit/s using a commerically available 1550 nm VCSEL. Experimental results show cascadable operation based on positive noise margin transfer characteristics and extinction ratio (ER) regeneration. Errorless performance is measured with sensitivity penalties of 0 and 1.4 dB and output ER exceeding 6 dB at 1 and 2.5 Gbit/s, respectively.     

800/1060 nm dual-wavelength pumped TDFA using single active pump source

Novel 800/1060 nm dual-wavelength pumping sources for Tm/sup 3+/-doped fibre amplifiers (TDFAs) are reported: a Nd/sup 3+/-doped silica fibre laser or a Nd/sup 3+/-doped microstructured silica fibre laser, both pumped near 800 nm and emitting near 1060 nm, providing the two required TDFA pump wavelengths. A new regime of pump power ratios is explored, in which the 800 nm power is comparable to the 1060 nm power. Gain and noise figure are comparable with those obtained using individual pump modules at the two wavelengths.     

800 nm亚波长夹层式金属偏振分束光栅

为获得高性能的偏振分束光栅,设计了一种亚波长夹层式金属光栅结构,通过严格耦合波分析和遗传算法优化出最佳光栅结构。所设计的光栅在波长为800 nm时,0级衍射级次上TM偏振波的透射率和TE偏振波的反射率分别为98%和96.5%。在波长747 nm 854 nm,以及入射角-27 27范围内,光栅的透射和反射消光比都大于20 dB,达到了高衍射效率、高消光比、宽带宽及大角度的要求,数值分析表明该光栅对周期、槽深、覆盖层厚度具有优良的工艺容差。该光栅结构简单,性能稳定,对入射光损耗低,偏振分束效果明显,在光学偏振器件、激光器系统、偏振成像等领域具有广泛的应用前景。     

Widely tunable mode-locked laser diodes using optical disk filter

We present a scheme for generating high-repetition-rate mode-locked optical pulses within a wide wavelength-tuning range. This scheme utilizes an external-cavity laser configuration with a disk-shaped bandpass filter (disk filter), which is set in the external cavity. The disk filter can tune its transmission wavelength by rotating parallel to the external mirror. This simple wavelength-tuning scheme allows a short external cavity, which is necessary for generating high-repetition-rate optical pulses. This paper describes a preliminary experimental demonstration exhibiting 100%-modulated mode-locked pulses at 8 GHz in the 1535-1587-nm range     

用于光盘系统的位相光栅

本文设计出一种用光盘系统的位相光栅，介绍了设计原理方法，采用傅里叶变换分析了衍射光束的空间频谱及光强分布。     

Evaluation of the 800 nm pump band for erbium-doped fiberamplifiers

Performs a comprehensive experimental and theoretical investigation of methods for overcoming the excited-state absorption (ESA), which is the main obstacle to efficient pumping of erbium-doped fiber amplifiers (EDFAs) at 800 nm. The effects of ESA on gain can be reduced at the cost of an additional noise penalty by adopting bidirectional pumping or by pumping in the long-wavelength tail of the ground-state absorption (GSA) band. The GSA and ESA cross-section spectra on the glass host material. One of the most promising hosts, fluorophosphate, is compared to Al/P silica in a detailed analysis based on a quantitative numerical model. It is predicted that 2-3 dB less pump power is required for the fluorophosphate EDFA. For Al/P-silica EDFAs, it is found that ~7-dB-higher power is required when pumping in the 800 nm band than for pumping at 980 and 1480 nm     

Highly reliable ferroelectric memories using BLT thin films and robust integration schemes

We report on highly reliable characteristics of 1-Mb ferroelectric memories based on 0.35-/spl mu/m CMOS technology ensuring ten-year retention and imprint at 175/spl deg/C, which have been successfully developed for the first time. This excellent reliability resulted from newly developed [Bi/sub 1-x/La/sub x/]/sub 4/Ti/sub 3/O/sub 12/ (BLT) ferroelectric films with superior reliability performance at high temperatures, and also resulted from robust integration schemes free from ferroelectric degradation due to process impurities such as moisture and hydrogen.     

梯度折射率光盘物镜

本文阐述新型便携型CD盘光学头光学系统,研讨梯度折射率光盘物镜的设计。     

An experimental photonic time-slot interchanger using optical fibers as reentrant delay-line memories

The system interchanges data from time slots in its input to time slots in its output. Carried by single-mode optical fibers and switched by lithium-niobate directional couplers, the data remains in photonic form from input to output. The data format is a series of frames, each with a start-bit andNtime slots withBbits each. An electronic controller reads the arbitrary one-to-one assignment ofNinput time slots toNoutput time slots (time-slot permutation) and orchestrates photonic directional couplers to steer the data among input, output, andNrecirculating fiber-optic delay lines. While a prototype withN = 3 , B = 8, and a pedestrian 90-MHz bit rate is a 3 × 3 switch, where each channel carries 28.8 Mbit/s, the basic design is not limited to these numbers.     

面向长距离通讯1550 nm垂直腔面发射激光器的研究

采用InP基衬底设计并制备了1550 nm垂直腔面发射激光器。采用混合镜面布拉格发射镜,其中顶部采用4.5对硅和二氧化硅的介电布拉格反射镜,同时采用隧道结的方式降低p层载流子吸收。制备出阈值电流在20 mA,室温直流下输出光功率为7 μW,激射波长为1554 nm,激射谱半高宽为3 nm的垂直腔面发射激光器。     

An 800 Mbit/s optical transmission experiment using a single-mode fiber

It has been confirmed by a preliminary transmission experiment that a repeater spacing at 800 Mbits/s can be lengthened up to 7.3 km, by using a combination of a low-loss single-mode fiber and a well designed AlGaAs laser. The laser is modulated by a signal current superimposed on a dc bias current above the threshold. This modulation scheme avoids the spectrum broadening of the laser at the cost of extinction ratio degradation. A discrepancy of about 13 dB exists between the measured and the calculated error-rate performance curves. The major part of the discrepancy, 10 dB, is due to the extinction ratio degradation.     

Ferroelectric optical image comparator using PLZT thin films

A PLZT thin film device has been constructed in which the photoinduced current represents the dot product between a stored image and an image projected onto its surface. One-dimensional autocorrelations have been performed by measuring this current while displacing the projected image. This device has the potential to perform as a high-resolution, high-speed optical comparator     

High-gain quantum-dot semiconductor optical amplifier for 1300 nm

Using an AlGaAs-GaAs waveguide structure with a six-stack InAs-InGaAs "dots-in-a-well" (DWELL) gain region having an aggregate dot density of approximately 8/spl times/10/sup 11/ cm/sup -2/, an optical gain of 18 dB at 1300 nm has been obtained in a 2.4-mm-long amplifier at 100-mA pump current. The optical bandwidth is 50 nm, and the output saturation power is 9 dBm. The dependence of the amplifier parameters on the pump current and the gain recovery dynamics has also been studied.     

用于光纤测量的1310nm/1550nm半导体激光驱动电源

为了实现光纤的精确快速测量, 设计了一种高稳定功率连续可调的1310nm/1550nm半导体激光驱动电源。该电源采用电流串联负反馈技术组成精密恒流源驱动半导体激光二极管,恒温控制电路驱动半导体制冷器,从而保证了激光器输出功率的稳定。控制器局域网络总线电路实现激光源的功率连续可调及激光的选择,通过变速积分PID控制算法消除了积分饱和,加速系统温度的稳定。采用激光保护和软启动电路,实现半导体激光器可靠稳定运行。结果表明,半导体激光器工作在室温25℃时,温度稳定性达0.01℃,激光长期输出功率稳定度达0.018dB。相对于传统的1310nm/1550nm半导体激光光源,该光源稳定性高、稳定速度快、体积小,方便光纤在线测量。     

Novel fabrication method of 120 nm period gratings using ECR-CVDSiNx films

120 nm period gratings were fabricated by a novel method using ECR-CVD SiN_x films. SiN_x films deposited on photoresist have a higher etching rate than that on the flat semiconductor substrate. Good use of this difference was made to fabricate gratings whose period is one-half that of the original, formed by a holographic exposure technique