Twin-Contact 645-nm Tapered Laser With 500-mW Output Power

High brightness tapered lasers emitting around 650 nm were developed. We realized 2-mm-long devices with 750- $mu$m straight section, 1250-$mu$m tapered section, and 4$^{circ}$ taper angle. The input currents into both sections were independently controlled. The laser reached 500-mW output power in continuous-wave operation in a nearly diffraction-limited beam quality. A modulation efficiency of 7.5 W/A was achieved.      

A Novel Intracavity Lens Design for Compact and High Efficiency Tapered Laser Diode

An integrated parabolic lens capable of introducing a diverging effect to the optical mode propagating within the cavity of a tapered laser is proposed and demonstrated. This idea allows broader high-power beams to be generated by shorter cavities. Diverging lenses with etch depths of 0.13 and 0.27 mum are implemented, with 12 (9.5%) and 16.8 mum (13.3%) overall broadening of the near-fields widths measured at 1/e² intensity. The peak output power as well as the threshold current is found to increase following the lens etching process, confirming the beneficial broadening effect introduced by the diverging lens     

Gigabit/s m-sequence generation

A known method of generating maximum-length sequences by employing delay lines in place of shift-register elements has been realised with base-coupled logic (b.c.l.). Sequences at speeds of up to 1.2 Gbit/;s have been produced.     

Characterization of Frequency Drift of Sampled-Grating DBR Laser Module Under Direct Modulation

The authors demonstrate the drift in frequency of a static sampled-grating distributed Bragg reflector (SG DBR) laser module when it is subjected to direct modulation. The magnitude of drift and its settling time is characterized as a function of the index of modulation. Results show that when the directly modulated SG DBR is optically filtered, as in a dense wavelength-division-multiplexed system, a power penalty of 6.7 dB is incurred in comparison to the unfiltered case.     

All-Optical Clock Recovery for 40-Gb/s MZM-Generated NRZ-DPSK Signals Using a Self-Pulsating DBR Laser

All-optical clock recovery for the nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) modulation format is demonstrated experimentally at 40 Gb/s using a self-pulsating distributed Bragg reflector laser. The use of a Mach–Zehnder modulator to generate the NRZ-DPSK signal yields a modulated signal spectrum with a weak clock tone. The self-pulsating laser is able to directly recover a clock signal with a root-mean-square timing jitter of 760 fs and an extinction ratio of 13 dB; a preprocessing stage to enhance the clock tone is not required. The timing jitter of the recovered clock signal is characterized for different values of the input signal optical signal-to-noise ratio and for varying amounts of waveform distortion due to polarization-mode dispersion.      

激光高效偏光镜的研究

给出了一种新型组合偏光镜设计；研究了激光高效偏光镜的机理；其性能测试表明：消光比优于１０－５，对非偏振光的透射比高达８９％。     

A 2.5-Gbit/s return-to-zero integrated DBR laser/modulatortransmitter

We demonstrate a novel modulation scheme in which both data-encoding and pulse generation are achieved using a single, wavelength tunable, integrated semiconductor laser/modulator. Data-encoded, near-transform limited 66 ps pulses are obtained at 2.5 Gbit/s and BER performance is reported     

高效率高功率全固态紫外激光器

报道了采用大功率国产光纤束模块端面抽运Nd∶YVO4激光晶体的腔外三倍频紫外激光器,用声光调Q技术实现了高功率高光束质量基频光输出。采用LBOⅠ类相位匹配和LBOⅡ类相位匹配的腔外倍频方法,并利用凹面反射镜的方式进行聚焦,避免了1064nm和532nm激光聚焦时由于波长的不同而产生的色差效应,有效地提高了三倍频的倍频效率。最终在注入抽运光功率为23.3W,声光调Q激光器的调制频率为20kHz的工作条件下,基频光输出功率为7.28W时,得到紫外激光输出功率为1.86W,1064nm基频光到355nm紫外激光的光-光转换效率为25.5%,此外,对紫外激光光束质量的测试表明,该紫外激光器具有高功率输出的同时仍有很好的光束质量。     

Gigabit/s indoor wireless systems with directional antennas

The design of a high speed (>150 Mb/s) wireless local area network (WLAN), requires that many factors be considered, including technical, economic, and regulatory. A major technical factor is the channel response behavior (multipath) in the indoor environment as a function of the frequency band, building type and radio system architecture. The consequences of designing indoor wireless systems with directional antennas at one or both ends of a line-of-sight (LOS) link are investigated. We determine how narrow the beamwidth must be so that the maximum data rate is not limited by multipath effects. For such beamwidths, simple unequalized two-level frequency shift keying (FSK) or phase shift keying (PSK) modems can be used in place of the more costly and complex “anti-multipath” modems, and data rates above 1 Gb/s may be achieved. The channel impulse response in an empty room is estimated using geometrical optics, observing that with directional antennas, multipath rays must arrive from the same direction as the LOS ray. The link outage probability is then estimated as a function of the antenna beamwidth, and guidelines are established for the selection of the frequency band and antenna placement. Experiments using a 19-GHz 622-Mb/s binary phase shift keying (BPSK) link and 15° beamwidth horn antennas in an office building with plaster walls and large metallized windows have demonstrated error-free performance on both LOS and non-LOS (NLOS) links     

单频DBR光纤激光器的设计

基于速率方程理论，给出ＤＢＲ光纤激光器单模运转的条件，并通过对光栅反射特性的分析及一些近似处理，进行了具体设计。对实际制作具有理论指导意义。     

高效率窄线宽掺铒光纤激光器

在介绍环形腔掺铒光纤激光器原理的基础上,对其功率及其线宽进行了研究,测得的激光光谱3dB带宽及其输出功率分别为0.05nm和45mW,明显高于文献[2]0.1nm和22.66mW的报道,最后分析了铒纤长度与阈值及输出功率的关系。     

高转换效率二极管激光器泵浦固体激光器

用两种泵浦光学系统对激光二极管输出光束的空间分布整形.研究了不同椭圆度和准直度的泵浦光束对Nd:YAG激光特性的影响.当椭圆度和准直度明显改善时.使泵浦光束在激光棒的整个长度上与激光腔模空间重迭度增大.泵浦功率密度提高.激光阈值下降.激光转换效率大幅度提高.泵浦功率为2.42W时,1064nm输出功率为1.13W.斜率效率为50%.并比较了两种不同浓度晶体的效率.     

高效率放电抽运KrF准分子激光器

248 nm放电抽运KrF准分子激光器在微电子学和医学等领域有重要的应用价值。在大多数应用中,激光器的最大输出效率和能量都是十分重要的参数。为了提高激光器输出效率和能量,实现KrF准分子激光器的稳定放电,采用新型开关电源和结构紧凑的张氏电极,并通过优化储能/放电电容比例和工作气体配比等方法,研制出了一台小型高效率放电抽运KrF准分子激光器。研究了开关电源对充放电特性的影响,以及气体配比对激光输出效率和能量的影响。该激光器的各项参数相比以往的产品有了较大改善,可重复频率为1~80 Hz,输出效率最高达2.5%,最大单脉冲输出能量380 mJ;当工作电压高于25 kV时,激光输出能量不稳定度约为1.8%。     

一种高效率的1060 nm半导体激光器设计

设计了一种高效的1060 nm大功率半导体激光器,该激光器包含有源层、波导层和光限制层。其中有源层采用InGaAs/GaAs量子阱（QW）结构,将该层控制在临界厚度范围内,提高腔内量子效率;波导层采用非故意掺杂GaAs材料非对称大光学腔结构,减小空腔损耗;光限制层采用掺杂的Al0.25Ga0.75As材料形成线性的过渡,以减小串联电阻。应用MOCVD对器件结构进行优化,外延,制作和封装测试,获得功率效率为47.4％的1060 nm半导体激光器。实验结果表明,腔内量子效率达到98.57％,腔损仅为0.273 cm-1。在室温下,QCW脉冲条件下制备的器件具有4 mm腔长和100μm条宽的器件,效率达到47.4％,峰值波长为1059.4 nm。     

用于实现激光高效率加工的光束整形技术

激光凭借其穿透性和高强度的独特优势,已在加工领域得到广泛应用,但为了实现激光加工的高效率、高精度指标,需要对激光进行空域整形和时域整形。空域整形技术主要是基于折射原理、衍射原理或偏振原理的整形技术,时域整形技术主要包括脉冲压缩技术和脉冲序列控制技术。     

新型高效的人眼安全OPO固体激光器

免调试谐振腔应用在内腔式Cr4+:YAG被动调Q的KTP光参量振荡(OPO)激光器中,获得综合性明显优于平平腔的结果:电光效率由2.27‰提高到2.70‰,1.57μm激光输出单脉冲能量由18 mJ提高到21.4mJ,脉宽由24ns压缩到7.8 ns,发散角由8 mrad减小到7 mrad.并发现定向棱镜腔激光输出能量、光轴指向、脉宽及波形等稳定性比平平腔均有显著改善.已研制出小型、高效、高稳定性、高光束质量的OPO激光器.     

Two-channel optical filtering of 1 Gbit/s signal with DBR filter

Distributed Bragg reflector (DBR) lasers have been used as tunable, narrow-band, amplifying optical filters and as tunable oscillators in two-channel, system experiments. A bit error rate of 10/sup -9/ with -25 dBm input power has been measured at 1 Gbit/s signal rate.<>     

高转换效率Nd∶YAG倍频激光器

介绍了两种Nd∶YAG倍频的方法 :折叠腔腔内倍频和腔外环形腔倍频 ,并着重对腔外环形腔倍频进行了研究 ,这种方法在 1kHz调QNd∶YAG激光 5 0W平均功率输入的情况下 ,获得了 1 7 5W平均功率的绿光输出 ,光 光转换效率达 35 % ,较好地解决了激光微细聚焦问题 ,更适用于激光微成型     

Modulation characteristics of tunable DFB/DBR lasers with one ortwo passive tuning sections

Calculation of the small-signal modulation characteristics of tunable distributed-feedback (DFB) and distributed Bragg reflector (DBR) lasers requires rate equations for the photon number, the phase of the electric field, and the carrier densities. Here, the rate equation for the photon number and phase is derived from an optical transmission-line model. Examples of the frequency- and intensity-modulation characteristics of a phase-tunable DFB laser are presented. The modulation responses exhibit the well-known relaxation resonance if either of the drive currents is modulated, but the possibility of complete removal of the resonance peak together with a perfect cancellation of spurious intensity modulation is also demonstrated. The frequency-modulation response then assumes a simple low-pass character with a cutoff frequency determined by the carrier lifetime in the passive tuning section. The importance of choosing the proper bias conditions is emphasized     

双向泵浦的高功率高效率钛宝石激光器

用脉冲调Ｑ的Ｎｄ：ＹＡＧ倍频激光器对一块１０．３ｍｍ长的钛宝石晶体实行双向泵浦，获得了８８ｍＪ的脉冲输出能量，３８．５％的转换效率和０．００３ｎｍ的线宽。