16-channel digitally tunable external-cavity laser with nanosecond switching time

We present a 16-channel 100-GHz-spacing digitally tunable packet-switching transmitter based on a novel external-cavity laser design. The transmitter can switch within 0.8 ns between its channels at 0-dBm output power and <0.7-dB penalty when switched from just above threshold and within 20 ns and 0.5-dB penalty when switched from below threshold. All 16 channels are within 2.1 GHz of the ITU grid.     

An integrated coupled-cavity 16-wavelength digitally tunable laser

We present a digitally tunable laser that was realized by coupling two wavelength periodical four-channel lasers. The lasers were coupled with a multimode interference coupler, in such a way that the device has a common intracavity output waveguide containing the full multiplexed signal. In the two laser cavities, 1 /spl times/ 4 PHASARs were used with a channel spacing of 100 and 400 GHz, respectively. By coupling each PHASAR to four semiconductor optical amplifiers, 4 /spl times/ 4 channels were generated. The measured SMSR for each of the 16 wavelengths is better than 40 dB.     

Submilliampere threshold buried-heterostructure InGaAs/GaAs singlequantum well lasers grown by selective-area epitaxy

Strained-layer InGaAs-GaAs-AlGaAs single quantum well buried heterostructure lasers grown by selective-area MOCVD are described. Threshold currents of 2.65 mA for an uncoated device and 0.97 mA for a coated device have been obtained. A peak optical output power of 170 mW per uncoated facet for a device with a 4 μm active region width was also achieved. Peak emissions wavelengths range from 0.956 to 1.032 μm     

High-power digitally tunable laser with integrated star coupler

A novel scheme for a digitally tunable laser requiring only P+Q+1 optical amplifiers for a device with in total P /spl times/ Q wavelength channels is presented A 32-channel InP/InGaAsP based device is fabricated. An optimised active layer and low on-chip losses result in a high optical output power.     

Stable and fast 100 GHz-spaced 30-channel digitally tunable operation in monolithically integrated semiconductor laser employing chirped ladder filter

Stable and fast 100 GHz-spaced 30-channel digital tuning operation with single longitudinal-mode oscillation in a monolithically integrated semiconductor diode laser has been achieved. It is experimentally demonstrated that the oscillation frequencies of the tunable laser were stabilised using the chirped ladder interferometric filter.     

Growth temperature dependence of InP nanopyramids grown by selective-area flow rate modulation epitaxy

We have grown InP nanopyramids by selective-area flow rate modulation epitaxy and investigated their structures with a high-resolution scanning electron microscope. The shape of InP nanopyramids strongly depends on growth temperature. At lower growth temperatures, InP forms two horns toward 1 1 1A directions. At higher growth temperatures, there were some thermal pits on {1 1 1}A sidewalls of InP nanopyramids. Furthermore, some droplets were observed on InP nanopyramids. In contrast, {1 1 1}B facets were stable even at high growth temperatures. The behaviors were discussed in relation to a crystallographic model.     

采用SAR结构的8通道12位ADC设计

本文设计实现了一个8通道12位逐次逼近型ADC。转换器内部集成了多路复用器、并/串转换寄存器和复合型DAC,实现了数字位的串行输出。整体电路采用HSPICE进行仿真,转换速率为133KSPS,转换时间为7.5μs。通过低功耗设计,工作电流降低为2.8mA。芯片基于0.6μmBiCMOS工艺完成版图设计,版图面积为2.5×2.2mm2。     

可调谐染料激光的窄谱宽输出

前言 可调谐染料激光器已被广泛地应用于激光光谱学、激光化学、同位素分离、医学和生物学等领域。在全息技术、光通讯、军事等方面染料激光器的应用也在不断扩大。在上述的许多应用中都要求有高的分辨率,而分辨率与激光输出的谱线宽度成反比。因而,如何压窄激光谱线宽度以达到提高分辨率是个很重要的课题。 使用棱镜扩束器的脉冲染料激光器,其优点是光学元件比较经济,准直容易,系统紧凑。适当地选择不同折射率的棱镜及其角度,可使染料激光输     

8通道10b的R-C混合式SARADC的设计

实现一个8通道10 b转换精度的逐次逼近式(SAR)模拟-数字转换器。在DAC的设计上采用新的电阻电容混合式的DAC的结构,和传统的C-R式结构相比具有更小的面积。同时对比较器的设计进行了优化,采用一个三级级联的准差分结构,并设计在传统的前置预放和锁存器级联的理论基础上,引入了交叉耦合负载,复位、钳位技术,获得了高精度和较低的功耗。设计经HSPICE仿真结果证明有效,并采用0.13μm CMOS工艺,分别采用2.5 V的模拟电源电压和1.2 V的数字电源电压供电,实现10位的精度。芯片面积为480μm*380μm,FF case下功耗为0.54 mW。实现了超低功耗的ADC的设计。     

Monolithic integration of thin film μ-heater array with 4-channel WDM transmitter

We integrated a μ-heater array with a multi-wavelength laser array for accurate control of the channel spacing. A μ-heater array was formed on a 4-channel laser array with asymmetric sampled gratings. The lasers showed threshold current of 9-13 mA and slope efficiency of around 0.21 W/A. High side mode suppression ratio over 44 dB was observed as well. With the μ-heaters, all the laser wavelengths were precisely controlled simultaneously. The laser wavelength was red shifted with the μ-heater and the tuning efficiency was 3.3 nm/W. However, thermal crosstalk between neighboring channels was observed and it was measured to be 1.1 nm/W.     

基于纳米球镜光刻的选区生长的光子晶体提高InGaN LED光提取效率的研究

We report a new method for the fabrication of two-dimensional photonic crystal(PhC) hole arrays to improve the light extraction of GaN-based light-emitting diodes(LEDs).The PhC structures were realized using nanospherical-lens photolithography and the selective-area epitaxy method,which ensured the electrical properties of the LEDs through leaving the p-GaN damage-free.At a current of 350 mA,the light output power of LEDs with PhC hole arrays of 450 nm and 600 nm in diameter with the same lattice period of 900 nm were enhanced by 49.3% and 72.2%,respectively,compared to LEDs without a PhC.Furthermore,the LEDs with PhC hole structures showed an obviously smaller divergent angle compared with conventional LEDs,which is consistent with the results of finite-difference time-domain simulation.     

一种可调的全密封大功率氦-氖激光管

本文介绍一种采用玻璃封接工艺制作的全密封大功率氦-激光管。该管系全内腔可调结构，腔长1米，在不同加磁场，不用氦-3的条件下，可在6328A输出40mW以上的多模功率，寿命可保用三年。     

Pulse tail suppression in laser diode output by tunable notchfilter

Efficient suppression of the relaxation oscillations in the output signal from an overdriven gain-switched laser diode is demonstrated for the first time by spectral filtering using a nonuniformly strained Fibre Bragg grating. As a result, a five-fold increase in the peak power is achieved for the tail-free operation     

Floating active inductor based Class-C VCO with 8 digitally tuned sub-bands

A fully integrated floating active inductor based voltage-controlled oscillator (VCO) is presented. The active inductor employs voltage differencing transconductance amplifier (VDTA) as a building block. The designed VCO achieves frequency tuning by varying the bias current through the VDTA and utilizes a Class-C topology for improving the phase noise performance. The inductor-less VCO is designed and implemented in a 45-nm CMOS process and its performance is estimated using Virtuoso ADE of Cadence. Operating at a supply voltage of ±1 V, the proposed VCO consumes 0.44–1.1 mW corresponding to the oscillation frequency of 1.1–1.8 GHz thereby exhibiting a tuning range of 48.27%. The phase noise of the VCO lies in the range of −94.12 to −98.37 dBc/Hz at 1 MHz offset resulting in a FOM of −172.14 to −176.69 dBc/Hz.     

Strained-layer InGaAs-GaAs-AlGaAs lasers with monolithicallyintegrated photodiodes by selective-area MOCVD

Fabrication, design, and operation of strained layer, InGaAs-GaAs-AlGaAs lasers with monolithically integrated photodiodes fabricated by selective-area epitaxy are presented. Threshold currents as low as 8 mA (~300 A/cm²) were obtained for uncoated devices operating cw at room temperature. A responsivity of 71 μA/mW was obtained for a device with a photodiode etched facet angle of 3° and a photodiode bias of 0 V     

Broadband emission from InGaAs-GaAs-AlGaAs LED with integratedabsorber by selective-area MOCVD

Three-step selective-area metal organic chemical vapour deposition is used to fabricate a strained layer InGaAs-GaAs-AlGaAs single quantum well broad spectrum LED with an integrated absorber. A tapered oxide width mask pattern is used for the active region regrowth to produce an edge emitting device with a continuous variation in the quantum well thickness and composition along its length. A maximum spectral width of 165 nm is obtained     

利用BF实现钛宝石激光器宽带可调谐激光输出

设计了一组双折射滤光片,由3片石英晶体组成,光轴倾角均为0°,基片厚度为0.45mm,3片厚度比为1:4:10.用于自行搭建的钛宝石激光器调谐实验,发现双折射滤光片绕其法线旋转约20°,输出激光中心波长可由760nm连续变化到845nm,并且线宽均小于2nm,最窄能达到0.73nm.泵浦能量465mJ时,800nm输出能量为85mJ.最大斜率效率为32.1%,最大光-光转换效率约为18.3%.双折射滤光片具有较好的调谐和压线宽作用.     

平坦功率输出的宽带波长可调光纤环型激光器

为了获得一种平坦功率输出的宽带波长可调的掺铒光纤环型激光器,提出采用一高双折射光纤环镜获得其平坦功率输出,在高双折射光纤环镜中,采用了大量的高双折射光纤段和偏振控制器,它们的反射光谱可补偿掺铒光纤环型激光器输出功率光谱的不平坦,通过压缩或者延伸激光腔里的分布式光纤布喇格光栅即可实现波长调谐。实验验证可以获得一种宽达38nm的宽带波长调谐(1527nm～1565nm),输出功率的不平坦被控制在±0．8dB范围之内,总输出功率大约4dBm、3dB线宽为0．01nm、旁瓣抑制比为48dB的光纤环型激光器。     

Reconfigurable WDM-PON empowered by a low-cost 8-channel directly modulated laser module

A 10 Gbit/s 16-km-long reconfigurable wavelength-division-multiplexing passive optical network (WDM-PON) is presented empowered by a low-cost multi-channel directly modulated laser (DML) module. Compared with the case using discrete devices in conventional scheme, the proposed DML module provides a cost-effective solution with reduced complexity. The clear eye diagram and the bit error rate (BER) of less than 2×10-7 with a sensitivity of ?7 dBm are obtained. Due to the special packaging design, the crosstalk between channels under condition of simultaneous operation can be negligible.     

调谐元件色散率对输出激光线宽的影响

建立了棱镜对系统三阶以内色散量的数学模型,精确计算了其解析解。给出了四棱镜与平面镜及四棱镜与光栅组合系统对输出激光线宽影响的物理图像。