Cryogenic operation of AlGaAs-GaAs vertical-cavity surface-emitting lasers at temperatures from 200 K to 6 K

We demonstrate for the first time the CW performance of AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) at cryogenic temperatures from 6 K to 200 K. By detuning the cavity mode with respect to the gain peak so that optimum dc lasing operation is achieved at -100 K, we find that this optimum lasing performance can be maintained down to temperatures as low as 6 K. Across a broad range of temperatures from 200 K to 6 K, the minimum threshold current of a 16-/spl mu/m diameter VCSEL stayed below 4 mA, while its -3-dB modulation bandwidth increased by about 70% to 11 GHz at 6 K, and the external slope efficiency is greater than 70%.     

外加电场下垂直腔面发射激光器的偏振转换电流

电光效应双折射可以控制垂直腔面发射激光器的偏振特性。本文计算了作用在垂直腔面发射激光器（VCSEL）的上面的分布格反射镜（DBR）上的外加电场产生的双折射,并在此基础上通过对自旋反转模型（SFM）的修正,得到面发射激光器在外加电场存在时的偏振转换电流。     

Vertical-cavity surface emitting lasers: moving from research tomanufacturing

After more than a decade of research, vertical-cavity surface emitting lasers (VCSELs) are making the transition into the manufacturing arena. We review unique VCSEL properties found in their structure, growth, fabrication, and performance, which have precipitated their commercial acceptance. The short optical cavity that is formed between two distributed Bragg reflector mirrors is a distinctive VCSEL attribute. The spectral alignment between the resonance of the optical cavity formed by these mirrors and the laser gain bandwidth is shown to influence the VCSEL performance. Thus, epitaxial VCSEL growth by metalorganic vapor-phase epitaxy aided by in situ reflectance monitoring is discussed with an emphasis on uniformity and reproducibility. We also describe the fabrication techniques and VCSEL structures used to obtain transverse electrical and optical confinement, including etched air-post, ion-implanted, and selectively oxidized VCSELs. For the latter, wet oxidation of AlGaAs to form buried-oxide apertures has enabled record laser performance, such as ultralow threshold current and high efficiency. Numerous applications for VCSELs have been identified that leverage their manufacturing and performance advantages     

隧道再生多有源区垂直腔面发射激光器光学特性研究

文章对隧道再生两个有源区内腔接触式垂直腔面发射激光器(VCSEL)光学特进行了研究。主要包括:通过纵向光场分布模拟分析了驻波效应;测量得到了VCSEL外延片量子阱增益谱峰值波长、谐振腔谐振波长、分布布喇格反射器(DBR)反射谱中心波长及材料的生长厚度偏差等重要信息,并结合增益谱,对该外延片制备的器件不激射的原因进行了分析解释。此外,对该外延片边发射模式特性进行模拟计算,由于DBR结构的存在,此结构的光场强度分布明显不同于普通的边发射激光器,模拟得到的远场发散角与测量结果相吻合。     

Temperature Dependence of 980-nm Oxide-Confined VCSEL Dynamics

Temperature dependence of 980-nm vertical-cavity surface-emitting laser (VCSEL) dynamics is reported. Resonance frequency and damping factor of a 7-m active diameter laser have been measured using noise spectra. The primary cause of reduced bandwidth with increasing temperature was reduced photon density. Differential gain is relatively constant for temperatures from 10 C to 70 C, and damping analysis showed there was also no significant change in -factor as a function of temperature.     

高功率980nm垂直腔面发射激光器的温度特性

应变补偿量子阱结构因带宽大、增益高和波长漂移速度低等特点而成为近年来研究的热点.首次介绍了国内980 nm 高功率InGaAs/GaAsP应变补偿量子阱结构的垂直腔面发射激光器(VCSEL) 变温实验,测得脉冲条件下600 μm直径的器件在10-100℃温度范围内发射波长漂移速度为0.05 nm/K,阈值电流随温度变化呈现先缓慢下降后迅速上升的特性.结合VCSEL反射谱、PL谱和增益峰值波长漂移速度,对器件阈值电流特性进行了合理的分析和解释.连续工作状态下,测试得到器件峰值功率为1 W,根据波长与耗散功率的实验曲线及热阻计算公式,可估算出垂直腔面发射激光器热阻值为10 K/W.     

Influence of optical feedback time-delay on power-drops in vertical-cavity surface-emitting lasers

The influence of optical feedback time delay on the average period of low-frequency fluctuations (LFF) in external cavity vertical-cavity surface-emitting lasers (VCSELs) is studied experimentally. The regularity of power dropouts is shown to increase with increased external cavity length. Coexistence of LFF and stable operation is observed when the external cavity length is close to the VCSEL coherence length.     

A novel wideband and circularly polarized cross‐dipole antenna

In this paper, we present a novel wideband circularly polarized (CP) composite, called cavity‐backed crossed dipole antenna for 2.45 GHz industrial, scientific, and medical (ISM) band wireless communication. To excite the CP radiation effectively, a curved‐delay line providing an orthogonal phase difference among the cross‐dipole elements is attached at corners of the sequentially rotated elements. By choosing a proper radius of the curved‐delay line, a wide input impedance of the antenna can be realized. Unlike conventional cross‐dipole antennas, the proposed cross‐dipole antenna is designed with an open stub added to the radiating arms of the dipole so that both impedance and axial ratio bandwidths are enhanced. The antenna is center‐fed by a 50‐Ω coaxial cable and is placed above a cavity‐backed reflector to obtain a directional CP radiation pattern. With the advantage of being center‐fed, a symmetric CP radiation pattern can be achieved across the entire operating bandwidth. To further improve the directivity and the radiation pattern, a rectangular cavity‐backed reflector is used. Simulated and measured results confirm that the proposed antenna has good CP characteristics. The proposed antenna obtains a broad 3‐dB axial ratio bandwidth of 49% (1.20 GHz, 1.96–3.16 GHz) and an impedance bandwidth of 67.7% (1.66 GHz, 1.69–3.35 GHz) for reflection coefficient (S₁₁) ≦ −10 dB. It also yields an average CP gain of 9.2 dBic across the operating bandwidth and a peak CP gain of 10 dBic. Copyright © 2016 John Wiley & Sons, Ltd.     

10-GHz 8.7-ps Pulse Generation From a Single-Mode Gain-Switched AlGaAs VCSEL at 850 nm

We have successfully generated a 10-GHz 8.7-ps pulse train at 850 nm by using a gain switching technique with a high-speed AlGaAs-based vertical-cavity surface-emitting laser (VCSEL). The VCSEL, which operates in a single transverse mode by employing an aluminum oxide aperture, has a modulation bandwidth of 6.3 GHz and a relaxation oscillation frequency at around 11.7 GHz. An error-free 10-Gb/s return-to-zero data modulation was demonstrated by using the generated 10-GHz pulse train.     

利用边发射光致发光谱研究垂直腔面发射激光器材料的特性

在室温下测量了GaInP/AlGaInP垂直腔面发射激光器(VCSEL)的光致发光谱和反射谱.通过反射谱测量可以很容易得到激光器的腔模波长.但是用通常的背散射配置不能测得与有源区中量子阱有关的光致发光信号.用边激发配置可以测到量子阱的光致发光谱,但这样测得的光谱已经受到激光器中的分布布拉格反射镜(DBR)的调制.采用腐蚀去上DBR层的方法可以在背散射配置下测得量子阱的光致发光谱,但仍无法避免下DBR层对发光谱的调制作用.从而只有采用边激发 边发射模式才能测得VCSEL中量子阱的真实的光致发光谱.     

基于耦合腔的VCSOAs增益带宽优化

垂直腔半导体光放大器(VCSOAs)的带宽通常较窄,通过改变其有源区一侧的DBR膜堆结构,构造无源腔与原有源腔相耦合的耦合腔结构可优化VCSOAs带宽.基于该结构模型,在反射工作模式下,利用传输矩阵方法对双腔和三腔结构的VCSOAs的增益带宽特性进行了分析.结果表明,在10dB的峰值增益水平下、带宽扩展至3nm以上,较单腔结构有了很大的提高,具有一定的现实参考意义.     

High-speed VCSEL of modulation bandwidth over 7.0 GHz and itsapplication to 100 m PCF datalink

High-speed vertical cavity surface emitting laser (VCSEL) with 6×6 μm active area is fabricated by reducing its pad area in order to reduce its parasitic capacitance. The fabricated VCSEL shows the 3 dB bandwidth of over 7 GHz and average threshold current of 0.7 mA. This is the highest 3 dB modulation bandwidth ever reported for the plan type bottom emitted laser with pad. The maximum intrinsic bandwidth as estimated from k-factor is found to be over 20 GHz, which is less than three times than the observed bandwidth. The thermal characteristics are also found to be almost unchanged due to the reducing of its pad size. It also showed open eye pattern for 3 GHz nonreturn to zero (NRZ) pseudorandom signal after transmission through 100 m large core plastic clad fiber (PCF), which could be used in short and medium distance optical links     

Design of a broadband planar cavity-backed circular patch antenna

This paper presents a design of a low-profile cavity-backed circular patch antenna for broadband applications. By using substrate integrated waveguide (SIW) based cavity and feeding mechanism, a planar cavity-backed patch antenna is realized. The proposed study demonstrates that a wide impedance bandwidth can be achieved by employing a rectangular SIW-based cavity underneath the conventional circular patch. Additionally, to generate circular polarization (CP), the patch has been reduced diagonally and shorted by a via-probe. Finally, a CP SIW-based antenna is designed and operating for a wide impedance bandwidth of 23.10% below −10 dB criteria, ranging from 9.09 GHz to 11.40 GHz and axial-ratio (AR) bandwidth of 270 MHz (10.30–10.57 GHz). The proposed design is fabricated by means of a printed circuit board (PCB) procedure. The simulated results are validated with the experimental one which agrees well with each other in the terms of S₁₁, antenna gain, AR and radiation patterns. Moreover, the proposed design exhibits unidirectional radiation characteristics with the measured peak gain of 6.6 dBic while maintaining planar integration.     

Modulation of a vertical-cavity surface-emitting laser using anintracavity quantum-well absorber

We demonstrate a novel modulation technique with a vertical cavity surface-emitting laser (VCSEL) using an intracavity embedded voltage-biased quantum well absorber. We achieved a -3-dB small-signal bandwidth of 9 GHz and a response of 7 GHz/√(mA) by modulation of the absorber. Our calculations show that this technique introduces significantly less chirp at higher frequencies than direct current modulation     

互注入VCSEL非线性及同步特性的理论研究

考虑到瓦注入耦合特有的非线性效应，建立了互注入式垂直腔面发射激光器（VCSEL）的理论模型，推导了系统注入锁定范围的解析表达式，理论研究了互注入的同步类型以及注入延时对系统非线性行为的影响。结果表明：在激光器参数相同的理想情况下，系统能实现完全同步，此时注入延时会影响VCSEL的运行状态；当存在参数偏差或噪声时，系统能实现延时同步，此时注入延时对同步质量的影响呈阶梯状。仿真结果验证了所推导的锁定范围表达式的正确性，发现注入锁定范围与注入量的平方根成难比。     

16信道0.35μm CMOS/VCSEL光发射模块

研究了垂直腔面发射激光器(VCSEL)及其列阵器件的光谱特性、调制特性、高频特性及与微电子电路的兼容性,将1×16的VCSEL与CMOS专用集成电路进行多芯片组装(MCM),混合集成为16信道VCSEL光发射功能模块.测试过程中,功能模块的光电特性及其均匀性良好,测量的-3dB频带宽度大于2GHz.     

17.3% peak wall plug efficiency vertical-cavity surface-emittinglasers using lower barrier mirrors

Modifications to the epitaxial growth of vertical-cavity surface-emitting laser (VCSEL) material have recently led to improved characteristics. By offsetting the quantum-well gain peak from the cavity mode, and implementing lower barrier p-type Al_0.67Ga _0.33As/GaAs DBR mirrors with parabolic interface gradings, better high-temperature operation and lower voltages have been achieved. These effects combine to yield a peak wall plug efficiency of 17.3% for room temperature, CW operation     

894 nm高温工作氧化限制型基横模VCSEL研究

针对芯片原子钟（铯）用激光光源系统对垂直腔面发射激光器（VCSEL）模式及工作温度的需求,研制出可以高温工作的氧化限制型基横模 894.6 nm VCSEL。通过缩小VCSEL氧化孔直径至3 μm,限制VCSEL高阶横模激射,保证器件基横模低阈值电流工作。通过常温下腔模与材料增益失谐12 nm 的结构设计,使器件能够在50~65 ℃ 高温时,激射波长对准原子能级且工作模式稳定。实验所制备的VCSEL在工作温度为55 ℃、注入电流1.8 mA 时,激射波长达到 894.6 nm,边模抑制比（SMSR）大于35 dB,基横模功率为0.75 mW,具有11.4°的远场发射角。当温度为65 ℃时,器件SMSR大于25 dB,基横模功率大于0.1 mW。该高温基横模工作的VCSEL在芯片原子钟中具有重要的应用前景。     

薄膜干涉型光学全通滤波器的设计与分析

设计并分析了用于多信道色谱补偿的薄膜Gires-Tournois干涉仪（GTI）型光学全通滤波（OAPF），讨论了反射镜的膜层结构对器件 的群延迟谱和反射谱的影响，。以及大角度入射引起的偏分离现象和幅度畸变现象，给出了单级和多级串拉OAPF的初步设计结果。