共振腔发光二极管专利技术综述

本文从共振腔发光二极管的原理和反射镜的设置出发,主要利用S系统中的CNABS、CNTXT、SIPOABS、DWPI等数据库的检索结果为分析样本,从专利文献的视角对共振腔发光二极管技术的发展进行了全面的统计分析,总结了与共振腔发光二极管相关的国外专利的申请趋势、主要申请人分布、IPC分布,并对共振腔发光二极管重点技术的发展路线进行了分析.     

微腔中nc-Si/SiN超晶格的光致发光

研究了一维光子晶体微腔结构对nc-Si/a-SiNz超晶格发射的调制.一维光子晶体微腔采用两种具有不同折射率的非化学组分非晶氮化硅的周期调制结构,腔中嵌入采用激光晶化方法制备的硅量子点阵列,从Raman谱和透射电子显微镜分析得到其尺寸约为3～4 nm.从光致发光谱上观察到明显的选模作用、明显变窄的发光峰以及约两个量级的发光强度的增强.微腔对硅量子点阵列发光的调制主要表现在两个方面:共振模式的增强和非共振模式的抑制.硅量子点中位于腔共振模式的辐射跃迁被增强,非共振模式的辐射跃迁被抑制,因此位于腔共振频率处的跃迁通道成为硅量子点中唯一的辐射跃迁通道,导致光致发光谱的窄化和强度的增强.因此,在提高硅材料发光效率方面,光子晶体微腔具有非常大的应用前景.     

微腔中nc-Si/SiN超晶格的光致发光

研究了一维光子晶体微腔结构对nc-Si/a-SiNz超晶格发射的调制.一维光子晶体微腔采用两种具有不同折射率的非化学组分非晶氮化硅的周期调制结构,腔中嵌入采用激光晶化方法制备的硅量子点阵列,从Raman谱和透射电子显微镜分析得到其尺寸约为3～4 nm.从光致发光谱上观察到明显的选模作用、明显变窄的发光峰以及约两个量级的发光强度的增强.微腔对硅量子点阵列发光的调制主要表现在两个方面:共振模式的增强和非共振模式的抑制.硅量子点中位于腔共振模式的辐射跃迁被增强,非共振模式的辐射跃迁被抑制,因此位于腔共振频率处的跃迁通道成为硅量子点中唯一的辐射跃迁通道,导致光致发光谱的窄化和强度的增强.因此,在提高硅材料发光效率方面,光子晶体微腔具有非常大的应用前景.     

微腔中nc-Si/SiN超晶格的光致发光

研究了一维光子晶体微腔结构对nc-Si/a-SiNz超晶格发射的调制. 一维光子晶体微腔采用两种具有不同折射率的非化学组分非晶氮化硅的周期调制结构，腔中嵌入采用激光晶化方法制备的硅量子点阵列，从Raman谱和透射电子显微镜分析得到其尺寸约为 3～4nm. 从光致发光谱上观察到明显的选模作用、明显变窄的发光峰以及约两个量级的发光强度的增强. 微腔对硅量子点阵列发光的调制主要表现在两个方面：共振模式的增强和非共振模式的抑制. 硅量子点中位于腔共振模式的辐射跃迁被增强，非共振模式的辐射跃迁被抑制，因此位于腔共振频率处的跃迁通道成为硅量子点中唯一的辐射跃迁通道，导致光致发光谱的窄化和强度的增强. 因此，在提高硅材料发光效率方面，光子晶体微腔具有非常大的应用前景.     

利用表面等离子体增强发光二极管发光效率的研究进展

表面等离子体(Surface plasmons,SPs)是近年来国际上研究的一个热点. SPs具有空间局域性,局域场增强等特点,可以用来增强发光二极管(Light-emitting diode,LED)的发光效率.利用表面等离子体场局域性质,在共振时SPs有很高的态密度,这能够影响发光中心的辐射速率,提高发光中心的内量子效率;并且可以制作合适的结构,控制光的出射方向,提高发光二极管的提取效率.近年很多研究小组研究了SPs增强发光效率的物理机理,并得到一些很好的结果,本文对现阶段的研究进展进行综述.     

表面等离子体提高GaN-LED发光效率的研究进展

表面等离子体能够增强氮化镓发光二极管的发光效率,为高效发光二极管芯片的研究提供了可行的方案。近年来,国内外研究小组在利用表面等离子体增强氮化镓发光二极管发光效率的实验中,取得了很多有价值的结果。介绍了具有金属薄膜、金属颗粒和金属光子晶体等典型结构的氮化镓发光二极管。重点探讨了表面等离子体增强发光二极管发光的机理、结构和关键技术。对具有二维金属光子晶体的氮化镓发光二极管发光增强机理进行了分析和预测,认为利用二维光子晶体可以从内量子效率和外量子效率两方面增强器件发光,并且有很好的可控制性,是提高发光效率的可行方案。     

MIDyM隧道发光二极管的研究

稀土元素Dy引入以玻璃为基底的隧道发光二极管（简称为MIDyMTD）后，其发光强度得到了明显提高，Ⅰ－Ⅴ特性的负阻现象变弱，并出现了较弱的量子共振隧穿现象。量子共振隧穿导致了起发光中介作用的SPP慢模式的增强，最终导致了MIDyMTD发光的增强。另外，以铌酸锂单晶片为基底的MIDYMTD出现了较大的负阻（峰：谷—7：1），并且发射光谱的短波方向出现了戏剧性的增加。     

微腔有机发光二极管

设计了由分布布拉格反射镜（ＤＢＲ）和金属反射镜面形成的微腔结构。利用８－羟基喹啉铝（Ａ１ｑ３）作为电子传输层兼作发光层,ＴＰＤ作为空穴传导层,了有机发光二极管（ＯＬＥＤ）和微腔有机发光二极管（ＭＯＬＥＤ）。发现ＭＯＬＥＤ的光谱工比ＯＬＥＤ的窄得多,而光密度则得到了增强,对腔长进行调节,ＭＯＬＥＤ光谱峰出现移动。实验结果与理论计算基本符合。     

基于锗量子点的硅基发光器件

硅基光源是实现硅基集成光电子芯片的核心器件,虽然近年来国内外已经取得多项重要成果,但适合于下一代大规模光电集成芯片的小尺寸、低功耗、工艺兼容的高效硅基发光器件仍然缺乏。文章介绍了基于嵌入光学微腔中的锗量子点实现硅基发光器件方面的研究成果,通过将分子束外延生长的锗自组装量子点嵌入硅光子晶体微腔中,实现了室温下处于通信波段的共振发光。通过在图形化衬底上生长实现锗量子点的定位,并精确嵌入光子晶体微腔中,实现了基于锗单量子点的硅基发光器件。     

Si基异质结构发光的研究现状

综述了Ｓｉ 基异质结构发光研究的现状。介绍了Ｓｉ 材料本身的本征发光、激子发光、杂质发光等特性,描述了掺Ｅｒ－ Ｓｉ 的发光、Ｓｉ 基量子结构（ 量子阱、量子点） 的光发射,重点研究ＳｉＧｅ／Ｓｉ 异质结构的发光性质。同时还对多孔Ｓｉ 发光、Ｓｉ 基发光二极管（ＬＥＤ） 与Ｓｉ 双极晶体管（ＢＪＴ） 集成、Ｓｉ 基上垂直腔面发射激光器（ＶＣＳＥＬ） 与微透镜的混合集成作了简要的介绍。     

Metal-mirror-based resonant-cavity enhanced light-emitting diodesby the use of a tunnel diode contact

We, for the first time, designed and fabricated resonant-cavity light-emitting diodes for high-speed optical communications using a tunnel diode contact scheme. Use of a tunnel diode provides extra freedom in designing the device contact and cavity mirror, which allows the realization of a resonant cavity without requiring distributed Bragg reflectors. The fabricated resonant-cavity light-emitting diodes have half the spectrum bandwidth and nearly triple the fiber-coupled power of noncavity devices     

Low-power phototransceiver arrays with vertically integratedresonant-cavity LEDs and heterostructure phototransistors

Low-power phototransceivers and phototransceiver arrays, with vertically integrated high-gain heterojunction phototransistors (HPTs) and resonant-cavity light-emitting diodes (RCLEDs), are demonstrated. A tunnel junction was used as a low resistance interconnect between the two devices. The input and output wavelengths are 0.63-0.85 and 0.98 μm, respectively. The phototransceiver exhibits an optical gain of 13 dB and power dissipation of 400 μW for an input power of 5 μW. The phototransceiver arrays demonstrate good uniformity, low optical crosstalk, and imaging capabilities     

High-efficiency resonant-cavity LEDs emitting at 650 nm

We fabricated resonant-cavity light-emitting diodes (LEDs) emitting at 650 nm. Compressively strained GaInP quantum wells were used as an active layer embedded between AlGaAs-AlAs Bragg mirrors. The Bragg mirrors formed a one-wavelength optical resonator. Two devices with different light-emitting areas were compared: 1) a large area chip (300 μm×300 μm) with a conventional LED contact and 2) a small area chip with an 80-μm light opening with an annular contact. Large devices are more suitable for high output power whereas the smaller devices might be useful for data transmission e.g., via plastic optical fibers. For epoxy-encapsulated large area devices, we achieved a maximum wall-plug efficiency of 10.2% and maximum output power of 12.2 mW at 100 mA. The small area LEDs yielded 2.9 mW at 20 mA and a maximum wall-plug efficiency of 9.5%     

High-Temperature Stability of 650-nm Resonant-Cavity Light-Emitting Diodes Fabricated Using Wafer-Bonding Technique on Silicon Substrates

AlGalnP-based visible 650-nm GalnP-AlGalnP resonant-cavity light-emitting diodes (RCLEDs) with high-temperature stability were fabricated by wafer-bonding techniques on Si substrates. In this study, the metal-bonding RCLEDs (MBRCLEDs) devices were designed with 84-mum apertures for light output. The MBRCLEDs with a maximum wall-plug efficiency of 13.7% were demonstrated at an injection current of 2.5 mA. In addition, the improved heat sinking of MBRCLEDs led to lower junction temperature, and resulted in a very low power decay of 0.31 dB from room temperature to 100degC at an injection current of 20 mA.     

Investigations of the fundamental quantum noise properties of resonant-cavity light-emitting diodes (rcleds)

We present first results of the investigations of the quantum noise properties of resonant-cavity light-emitting diodes (rcleds). We obtain a quantum noise of up to ?0.07dB below the shot noise quantum limit already at moderate pump levels and when being pumped by a quiet current source. This amount of observed sub-shot noise emission is in accordance with the quantum efficiency of the devices. This Sub-Poisson intensity noise ofrcleds together with their narrow beam characteristics make them very attractive for applications in photonics and metrology.     

Impact of Nonlinear LED Transfer Function on Discrete Multitone Modulation: Analytical Approach

Light-emitting diodes constitute a low-cost choice for optical transmitters in medium-bit-rate optical links. An example for the latter is local-area networks. However, one of the disadvantageous properties of light-emitting diodes is their nonlinear characteristic, which may limit the data transmission performance of the system, especially in the case of multiple subcarrier modulation, which is starting to attract attention in various applications, such as visible-light communications and data transmission over polymer optical fibers. In this paper, the influence of the nonlinear transfer function of the light-emitting diodes on discrete multitone modulation is studied. The transfer function describes the dependence of the emitted optical power on the driving current. Analytical expressions for an idealized link were derived, and these equations allow the estimation of the power of the noise-like, nonlinear crosstalk between the orthogonal subcarriers. The crosstalk components of the quadrature and in-phase subcarrier components were found to be independent and approximately normally distributed. Using these results, the influence of light-emitting-diode nonlinearity on the performance of the system was investigated. The main finding was that systems using a small number of subcarriers and/or high QAM level exhibit a large signal-to-noise-ratio penalty due to the nonlinear crosstalk. The model was applied to systems with white and resonant-cavity light-emitting diodes. It is shown that the nonlinearity may severely limit the performance of the system, particularly in the case of resonant-cavity light-emitting diodes, which exhibit a strong nonlinear behavior.     

Resonant cavity LED's optimized for coupling to polymer opticalfibers

Planar resonant-cavity light-emitting diodes have been optimized to meet optical interconnect requirements. The microcavity effect is exploited to increase the extraction efficiency into a given numerical aperture and to reduce the crosstalk in parallel optical interconnect applications. Devices are fabricated with an overall quantum efficiency of 3.7% into a polymer optical fiber with a numerical aperture of 0.5 and a FWHM beam divergence angle of 105° at a drive current of 1 mA     

Characterization of Microwave Variable Capacitance Diodes

This paper will describe the electrical characterization of microwave variable capacitance diodes. The importance of some of the diode parameters is discussed from the application point of view, and suitable measurement techniques for these parameters are described, together with actual measurement data on some diodes. First, a general four-terminal transformation method is used, and some approximations lead to a fairly easy and accurate method of studying device characteristics. A resonant-cavity method is also considered, and it is explained under what condition it leads to a very simple test of the diode Q. Finally, a method is presented which is based upon modifications of the Weissfloch canonical network. These simplifications can be used to get an easy interpretation of the junction impedance or the diode Q.     

Variable numerical-aperture temporal-coherence measurement of resonant-cavity LEDs

The first interferometric measurements of temporal-coherence length variation with numerical aperture (NA) are described for 650 nm, resonant-cavity light-emitting diodes (LEDs) agreeing with spectrally derived results. The interferometrically measured coherence length (22 /spl mu/m to 32 /spl mu/m) reduced by 37% for a 0.42 increase in NA. For a larger range of NA (0-1), this would give coherence lengths (10 /spl mu/m-40 /spl mu/m) lying in the gap between that of conventional LEDs (/spl sim/5 /spl mu/m) and superluminescent diodes (/spl sim/60 /spl mu/m).     

Design and fabrication of temperature-insensitive InGaP-InGaAlP resonant-cavity light-emitting diodes

Visible InGaP-InGaAlP resonant-cavity light-emitting diodes with low-temperature sensitivity output characteristics were demonstrated. By means of widening the resonant cavity to a thickness of three wavelength (3/spl lambda/), the degree of power variation between 25 /spl deg/C and 95 /spl deg/C for the devices biased at 20 mA was apparently reduced from -2.1 dB for the standard structure design (1-/spl lambda/ cavity) to -0.6 dB. An output power of 2.4 mW was achieved at 70 mA. The external quantum efficiency achieved a maximum of 3% at 13 mA and dropped slowly with increased current for the device. The external quantum efficiency at 20mA dropped only 14% with elevated temperature from 25 /spl deg/C to 95/spl deg/C. The current dependent far-field patterns also showed that the emission always took place perfectly in the normal direction, which was suitable for plastic fiber data transmission.