III‐V/silicon photonics for on‐chip and intra‐chip optical interconnects

In this paper III‐V on silicon‐on‐insulator (SOI) heterogeneous integration is reviewed for the realization of near infrared light sources on a silicon waveguide platform, suitable for inter‐chip and intra‐chip optical interconnects. Two bonding technologies are used to realize the III‐V/SOI integration: one based on molecular wafer bonding and the other based on DVS‐BCB adhesive wafer bonding. The realization of micro‐disk lasers, Fabry‐Perot lasers, DFB lasers, DBR lasers and mode‐locked lasers on the III‐V/SOI material platform is discussed.     

硅基光源的研究进展

随着人们对大容量、高速和低成本的信息传播的要求越来越迫切, 近年来硅基光电子学得以蓬勃发展, 但硅基光源一直没有得到真正的解决, 成为制约硅基光电子学发展的瓶颈. 硅的间接带隙本质给高效硅基光源的实现带来很大困难, 实用化的硅基激光是半导体科学家长期奋斗的目标. 本文分别介绍了硅基发光材料、硅基发光二极管和硅基激光的研究进展, 最后总结了目前各种硅基光源面临的问题和未来的发展方向.     

Ultra‐low loss waveguide platform and its integration with silicon photonics

Planar waveguides with ultra‐low optical propagation loss enable a plethora of passive photonic integrated circuits, such as splitters and combiners, filters, delay lines, and components for advanced modulation formats. An overview is presented of the status of the field of ultra‐low loss waveguides and circuits, including the design, the trade‐off between bend radius and loss, and fabrication rationale. The characterization methods to accurately measure such waveguides are discussed. Some typical examples of device and circuit applications are presented. An even wider range of applications becomes possible with the integration of active devices, such as lasers, amplifiers, modulators and photodetectors, on such an ultra‐low loss waveguide platform. A summary of efforts to integrate silicon nitride and silica‐based low‐loss waveguides with silicon and III/V based photonics, either hybridly or heterogeneously, will be presented. The approach to combine these integration technologies heterogeneously on a single silicon substrate is discussed and an application example of a high‐bandwidth receiver is shown.     

Mode locked and distributed feedback silicon evanescent lasers

Electrically pumped lasers that can be made on silicon and integrated with other components are important in order to take full advantage of the capabilities of silicon photonics. In this paper we review two specific types of hybrid silicon evanescent lasers that can fulfill these requirements. We discuss recent results of distributed feedback (DFB) lasers and mode locked lasers made on silicon using evanescent coupling to thin films of III‐V material. Device designs and test results are discussed in detail.     

On‐chip stimulated Brillouin Scattering for microwave signal processing and generation

Demonstration of continuously tunable delay, low‐noise lasers, dynamically controlled gratings, and optical phase shifting using the stimulated Brillouin scattering (SBS) process has lead to the emergence of SBS as a promising technology for microwave photonics. On‐chip realization of SBS enables photonic integration of microwave photonic signal processing and offers significantly enhanced performance and improved efficiency. On‐chip stimulated Brillouin scattering is reviewed in the context of slow‐light based tunable delay, low‐noise narrow linewidth lasers and filtering for integrated microwave photonics. A discussion on key material and device properties, necessary to enable on‐chip Brillouin scattering using both the single‐pass and resonator geometry, is presented along with an outlook for photonic integration of microwave signal processing and generation in other platforms.     

Quantum dot lasers and integrated optoelectronics on silicon platform Invited Paper

Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot (QD) lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of selforganized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength (> 1.3 μm) QD lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.     

氮流量在高氢氛围中对富硅氮化硅薄膜材料结构及其发光特性的影响

采用等离子体增强化学气相沉积技术,以N₂掺入到SiH₄和H₂的沉积方式,分别在玻璃和N型单晶硅片(100)衬底上制备富硅氮化硅薄膜。通过紫外-可见光吸收光谱、傅里叶变换红外吸收光谱(FTIR光谱)、拉曼光谱和光致发光谱(PL谱)分别表征掺氮硅薄膜材料的带隙、结构及其发光特性的变化。结果表明：在氢气的氛围中,随着氮气流量的增加,氢原子能够对薄膜缺陷起到抑制作用,并使较低的SiH₄/N₂流量比下呈现富硅态,但却不利于硅团簇的形成。随着氮原子的掺入,Si—N键的含量增大,带隙增大,薄膜内微结构的无序度也增大,薄膜出现了硅与氮缺陷相关的缺陷态发光;随着氮原子进一步增加,出现了带尾态发光,进一步讨论了发光与结构之间的关联。这些结果有助于采用PECVD制备富硅氮化硅对材料发光与结构特性的优化。     

Nanosilicon photonics

Silicon photonics is no longer an emerging field of research and technology but a present reality with commercial products available on the market, where low‐dimensional silicon (nanosilicon or nano‐Si) can play a fundamental role. After a brief history of the field, the optical properties of silicon reduced to nanometric dimensions are introduced. The use of nano‐Si, in the form of Si nanocrystals, in the main building blocks of silicon photonics (waveguides, modulators, sources and detectors) is reviewed and discussed. Recent advances of nano‐Si devices such as waveguides, optical resonators (linear, rings, and disks) are treated. Emphasis is placed on the visible optical gain properties of nano‐Si and to the sensitization effect on Er ions to achieve infrared light amplification. The possibility of electrical injection in light‐emitting diodes is presented as well as the recent attempts to exploit nano‐Si for solar cells. In addition, nonlinear optical effects that will enable fast all‐optical switches are described.     

Erbium‐doped integrated waveguide amplifiers and lasers

Erbium‐doped fiber devices have been extraordinarily successful due to their broad optical gain around 1.5–1.6 µm. Er‐doped fiber amplifiers enable efficient, stable amplification of high‐speed, wavelength‐division‐multiplexed signals, thus continue to dominate as part of the backbone of longhaul telecommunications networks. At the same time, Er‐doped fiber lasers see many applications in telecommunications as well as in biomedical and sensing environments. Over the last 20 years significant efforts have been made to bring these advantages to the chip level. Device integration decreases the overall size and cost and potentially allows for the combination of many functions on a single tiny chip. Besides technological issues connected to the shorter device lengths and correspondingly higher Er concentrations required for high gain, the choice of appropriate host material as well as many design issues come into play in such devices. In this contribution the important developments in the field of Er‐doped integrated waveguide amplifiers and lasers are reviewed and current and future potential applications are explored. The vision of integrating such Er‐doped gain devices with other, passive materials platforms, such as silicon photonics, is discussed.     

Two‐dimensional microcavity lasers

Advances in processing technology, such as quantum‐well structures and dry‐etching techniques, have made it possible to create new types of two‐dimensional (2D) microcavity lasers which have 2D emission patterns of output laser light although conventional one‐dimensional (1D) edge‐emitting‐type lasers have 1D emission. Two‐dimensional microcavity lasers have given nice experimental stages for fundamental researches on wave chaos closely related to quantum chaos. New types of 2D microcavity lasers also can offer the important lasing characteristics of directionality and high‐power output light, and they may well find applications in optical communications, integrated optical circuits, and optical sensors. Fundamental physics of 2D microcavity lasers has been reviewed from the viewpoint of classical and quantum chaos, and recently developed theoretical approaches have been introduced. In addition, nonlinear dynamics due to the interaction among wave‐chaotic modes through the active lasing medium is explained. Applications of 2D microcavity lasers for directional emission with strong light confinement are introduced, as well as high‐precision rotation sensors designed by using wave‐chaotic properties.     

Whispering gallery microcavity lasers

Whispering gallery mode (WGM) optical microresonators have attracted intense interests in the past decades. The combination of high quality factors (Q) and small mode volumes of modes in WGM resonators significantly enhances the light‐matter interactions, making them excellent cavities for achieving low threshold and narrow linewidth lasers. In this Review, the progress in WGM microcavity lasers is summarized, and the laser performance considering resonator geometries and materials as well as lasing mechanisms is discussed. Label‐free detection using WGM resonators has emerged as highly sensitive detection schemes. However, the resolution is mainly limited by the cavity Q factor which determines the mode linewidth. Microcavity lasers, due to their narrow laser spectral width, could greatly improve the detection resolution. Some recent developments in sensing using microcavity lasers are discussed.     

Ultrafast fiber lasers for strong‐field physics experiments

The recent demonstration of rare‐earth‐doped fiber lasers with a continuous‐wave output power approaching the 10‐kW level with diffraction‐limited beam quality proves that fiber lasers constitute a scalable solid‐state laser concept in terms of average power. In order to generate high peak power pulses from a fiber several fundamental limitations have to be overcome. This can be achieved by novel experimental strategies and fiber designs that offer an enormous potential towards ultrafast laser systems combining high average powers (> kW) and high peak power (> GW). In this paper the challenges, achievements and perspectives of ultrashort pulse generation and amplification in fibers are reviewed. This kind of laser system will have a tremendous impact on strong‐field physics experiments, such as the generation of coherent light by high‐harmonic generation. So far, applications in the interesting EUV spectral range suffer from the very low photon count leading to nonrelevant integration times with highly sophisticated detection schemes. High repetition rate high average power fiber lasers can potentially solve this issue. First demonstrations of high repetition‐rate strong‐field physics experiments using novel fiber laser systems will be discussed.     

硅基光子集成研究进展

报道了国际上关于硅基光子集成的最新研究进展和本课题组在该领域的研究成果,包括对一些光收发模块、III-V族/硅基激光器等集成器件的结构改进和工艺的探索,展示了兼容互补金属氧化物半导体工艺的硅基光子集成在信息技术领域中的巨大前景.可以预见,硅基光子集成已成为硅光子学的主要研究内容,硅光子学及硅基光子集成的发展目标是趋向更高速率、更低功耗及更大集成密度.     

Q‐switched and modelocked all‐fiber lasers based on advanced acousto‐optic devices

The interest in all‐fiber lasers is stimulated by the inherent advantages they have over bulk lasers in aspects such as heat dissipation and robustness. The performance of Q‐switched and modelocked fiber lasers can benefit enormously from the development of all‐fiber configurations. A fiber laser with strictly all‐fiber components can fulfil the requirements of mechanical stability, low maintenance, enhanced power efficiency, simplified assembly process, and low cost. In this framework, recent developments infiber acousto‐optic devices are reviewed that have demonstrated new possibilities for actively Q‐switched distributed feedback fiber lasers, modelocking lasers and doubly active Q‐switched modelocked lasers. The aim is to demonstrate the great potential of infiber devices for the active control of different types of fiber lasers.     

硅基III-V族量子点激光器的发展现状和前景

本文简要综述了硅基III-V族量子点激光器的研究进展. 在介绍了量子点激光器的优势和发展后, 重点介绍了近年来硅基、锗基III-V族量子点材料生长上的突破性进展及所带来的器件性能的大幅提高, 如实现了锗基和硅基1.3 μm InAs/GaAs量子点激光器的室温激射, 锗基量子点激光器的阈值电流低至55.2 A/cm²并可达60 ℃以上的连续激射, 通过锗硅虚拟衬底, 在硅基上实现了30 ℃下以16.6 mW的输出功率达到4600 h的激光寿命, 这些突破性的进展为硅基光电子集成打开了新的大门.     

Lasers as Light Sources for Analytical Atomic Spectrometry

Abstract

Lasers have advantages compared to conventional light sources, which include high power, a monochromatic emission profile, stability, and rapid tuning across an atomic line. These advantages have resulted in superior analytical figures of merit and methods of background correction compared to conventional light sources. The most widely used lasers for atomic spectrometry include dye laser systems, optical parametric oscillator systems, and diode lasers. Three principal techniques employ lasers as light sources. Laser‐excited atomic fluorescence spectrometry (LEAFS) involves the use of laser light to excite atoms that emit fluorescence and serves as the analytical signal. Laser‐enhanced ionization (LEI) involves laser excitation of atoms to an excited state energy level at which collisional ionization occurs at a higher rate than from the ground state. Diode laser atomic absorption spectrometry (DLAAS) employs a DL as a source to excite atoms in an atom cell from the ground state to an excited state. The analytical signal is involves the ratio of the incident and transmitted beams. Recent applications of these techniques are discussed, including practical applications, hyphenated techniques employing laser‐induced plasmas, and work to characterize fundamental spectroscopic parameters.     

内壳层跃迁--实现超短波长激光的途径

内壳层跃迁机制是实现超短波长激光的一种很有潜力的方案，随着近年来超短超强激光技术和X射线激光实验方法的进展，实现内壳层跃迁机制的超短波长硬X射线激光不再是遥不可及的梦想，文章详细介绍了内壳层跃迁机制X射线激光的原理，并讨论了开展内壳层跃迁机制X射线激光实验的一些实际相关问题。     

Silicon photonics: from a microresonator perspective

Silicon photonics leverages the optical, electrical and material properties of silicon and the mature complementary metal‐oxide semiconductor (CMOS) nanofabrication technique to develop on‐chip photonic integration, which has been making significant impacts in various frontiers including next‐generation optical communications networks, on‐chip optical interconnects for high‐speed energy‐efficient computing and biosensing. Among many optical structures fabricated on silicon chips, microresonators due to their high‐Q resonances and small footprints play important roles in various devices including lasers, filters, modulators, switches, routers, delays, detectors and sensors. This paper reviews from a microresonator perspective some of the latest progress in the field, summarizes design considerations in various applications and points out key challenges and potentials.     

Functional organic single crystals for solid‐state laser applications

Because of long‐range order and high chemical purity, organic crystals have exhibit unique properties and attracted a lot of interest for application in solid‐state lasers. As optical gain materials, they exhibit high stimulated emission cross section and broad tunable wavelength emission as similar to their amorphous counterpart; moreover, high purity and high order give them superior properties such as low scattering trap densities, high thermal stability, as well as highly polarized emission. As electronic materials, they are potentially able to support high current densities, thus making it possible to realize current driven lasers. This paper mainly describes recent research progress in organic semiconductor laser crystals. The building molecules, crystal growth methods, as well as their stimulated emission characteristics related with crystal structures are introduced; in addition, the current state‐of‐the‐art in the field of crystal laser devices is reviewed. Furthermore, recent advances of crystal lasers at the nanoscale and single crystal light‐emitting transistors (LETs) are presented. Finally, an outlook and personal view is provided on the further developments of laser crystals and their applications.