Microresonator array for high-resolution spectroscopy

We investigated the properties of an array of spherical microresonators used as a miniaturized high-resolution spectroscopic device. Sixteen spherical microspheres made from polymethyl methacrylate were placed on a microscope slide serving as an optical wave guide. Light of a tunable narrowband laser source was coupled into this slide so that an evanescent wave was excited on the topside of the slide, where the resonators were placed. This evanescent field generated a particular intensity pattern in the array that depended sensitively on the wavelength. After calibration, that pattern was recorded by a CCD camera and used to identify the wavelength with a resolution of R ~ lambda/Deltalambda = 7 x 10(4).     

一种新型高灵敏度光学微环湿度传感器

提出了以聚酰亚胺（PI）为感湿材料的三耦合点单微环新型湿度传感器。外界湿度变化使得聚酰亚胺SOI微环谐振特性发生变化,最终通过谐振波长的漂移量确定湿度值。讨论了不同部位感湿时系统的传感特性,并且选择了最佳湿敏元件。数值模拟结果表明：与传统的单微环传感器相比,新型传感器具有较高灵敏度和测量范围,Through端口的自由频谱范围可提高3倍。三耦合点单微环谐振器整体结构可作为最佳湿敏元件,该传感器在10%RH~80%RH相对湿度范围内,灵敏度可达到0.98 nm/%RH,该结构为制备高灵敏度可集成微型湿度传感器件提供了一定的理论依据。     

Microresonator Kerr frequency combs with high conversion efficiency

Microresonator‐based Kerr frequency comb (microcomb) generation can potentially revolutionize a variety of applications ranging from telecommunications to optical frequency synthesis. However, phase‐locked microcombs have generally had low conversion efficiency limited to a few percent. Here we report experimental results that achieve conversion efficiency ( on‐chip comb power excluding the pump) in the fiber telecommunication band with broadband mode‐locked dark‐pulse combs. We present a general analysis on the efficiency which is applicable to any phase‐locked microcomb state. The effective coupling condition for the pump as well as the duty cycle of localized time‐domain structures play a key role in determining the conversion efficiency. Our observation of high efficiency comb states is relevant for applications such as optical communications which require high power per comb line.

     

Luminescent Properties of Carbon Nanodots Bound to the Surface of Spherical Microresonator

Physics of the Solid State - Hybrid structures consisting of emitting carbon nanodots bound to the surface of monodisperse spherical silica particles, which function as microresonators, are...     

Optomechanically Induced Mode Transition and Spectrum Enhancement in a Microresonator System

Optomechanics describes the interconnection between the terahertz optical field and mechanical microwave field, making it appealing in the context of nanophotonics and quantum information science. Here, the optomechanically induced mode transition and spectrum enhanced phenomenon in an optomechanical microcavity system are studied. An optical filter that is limited by the bandwidth of the mechanical mode is built. The analytical model is presented by considering a microresonator system which supports two electromagnetic modes and a single mechanical mode. Through the filtering of mechanical resonator, the optical spectral width becomes similar to the mechanical resonator bandwidth which can go beyond the limit of the cavity quality factor. It is found that the transition between the optomechanically induced transparency and the optomechanically induced absorption can be observed by tuning the coupling between the microresonator and the waveguide. Moreover, the controllable nonreciprocal excitation of the system can also be observed.     

Micromechanical Photonics: Microresonator Displacement Measurement by an Extremely-Short-Length External Cavity Laser Diode

A composite cavity laser diode was used to monitor the displacement of the external cavity microresonator from the phase difference in the near field. The carrier-to-noise ratio was very high (more than 45 dB) because of the lack of mode hopping noise due to the extremely short (less than 3 μm) external cavity length and strong optical feedback. The small distance (near field) allows a lensless system, making it easier to integrate on a gallium arsenide (GaAs) substrate.     

Photovoltaic devices

The term photovoltaics refers to the process whereby the energy in light is directly converted into useful electrical energy. Sunlight is abundant and free; hence, the conversion of this effectively inexhaustable energy source into electrical energy by photovoltaics is of considerable interest. Photovoltaic devices for solar energy conversion (solar cells) are the subject of this article.     

分子器件的研究进展

分子器件作为下一代电子器件近年来得到了迅速的发展.文章回顾了分子器件的发展历程和研究现状,并重点对分子导线、分子开关、分子整流器和分子晶体管等器件进行了介绍.     

Electron waveguide devices

The discovery of electron waveguiding in one-dimensional (1D) semiconductor nanostructures has uncovered a new regime of electron transport with fascinating physics. The device potential of electron waveguides, however, remains largely unexplored. Over the last few years, our interuniversity team has been conducting research on the physics, technology and opportunities for device applications of split-gate AlGaAs/GaAs electron waveguides. We have examined electronic devices based on electron transport, tunneling and interference. Many problems have been identified in transport-type devices, but much more research is required before the engineering potential of tunneling and interference devices is understood. We have also investigated the potential of electron waveguides in photonic applications, with emphasis on far-infrared (or THz) photodetectors. Our research to date has revealed strong photon-induced currents in antenna-coupled electron waveguides that arise from quantum thermopower. Far-infrared photodetectors based on photon-induced quantum transport remain an interesting opportunity for the application of electron waveguides.     

Multimode planar devices

We derive simple analytical expressions, using geometric optics, to describe the power output characteristics of various multimode devices, including acute angle X-junctions, symmetric Y-junctions and multimode interference couplers. The ray-tracing results compare well with results obtained using a finite difference beam propagation method solution of the governing scalar wave equation.     

Photonic crystal devices

We developed photochemically controlled photonic crystals which may be useful in novel recordable and erasable memories and/or display devices. These materials can operate in the UV, visible or near IR spectral regions. Information is recorded and erased by exciting the photonic crystal with ∼ 360 nm UV light or ∼ 480 nm visible light. The recorded information is read out by measuring the photonic crystal diffraction wavelength. The active element of the device is an azobenzene functionalized hydrogel which contains an embedded crystalline colloidal array. UV excitation forms cis-azobenzene while visible excitation forms trans-azobenzene. Larger dipole moment of the cis-form results in decrease of the free energy of mixing which causes the hydrogel to swell and to red-shift the photonic crystal diffraction with a 36 s time constant. We also observed fast ms and sub-ms transient dynamics associated with convection due to heating of the medium by UV excitation. Convective motion of the medium stretches the PCCA for about 6 μs within which the convection decays and the elastic restoring force of the PCCA brings back the stretched PCCA to its equilibrium state with 33 μs time constant. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Thin-film waveguide devices

This paper reviews a variety of practical or potential uses of low optical loss thin-film waveguides for light modulation, deflection, and switching. Emphasis is given to those thin-film devices that most likely will become necessary replacements of the bulk for systems involving signal processing, imaging radar, and optical communication in the infrared.     

Spintronics intelligent devices

Intelligent computing paradigms have become increasingly important for the efficient processing of massive amounts of data.However, using traditional electronic devices to implement these intelligent paradigms is currently mismatched and limited by their energy, area, and speed. Spintronics, which exploits the magnetic and electrical properties of electrons, could break through these limitations and bring new possibilities to electrical devices. In particular, the tunneling magnetoresistance eff...     

Holographic memory devices

The design principles are outlined for two kinds of holographic memory device: the serial store, and the mass store. The latter type is shown to be the most promising and details are given of one such device constructed by the authors and their co-workers.     

Quantum-based electronic devices

Microstructure technology provides a major element of the technology needed to realize envisioned quantum-based electronic devices. Quantum transport and quantum device research results indicate clearly the physical regimes and basic operating principles for some classes of quantum-based electronic devices. These same results also highlight current deficiencies in the full technology needed to realize small, ultrahigh speed quantum-based electronic devices.     

Generation of Optical Frequency Combs in an Optical Microresonator Pumped by a 780-nm Laser Diode in Self-Injection Locking Regime

Journal of Experimental and Theoretical Physics - Experimental data for the generation of optical frequency combs in magnesium fluoride microcavities with whispering gallery modes at 780 nm are...     

功能聚合物:从薄膜器件到纳米器件

文章简要回顾了功能聚合物的发现和发展历程,着重介绍了其在发光二极管、太阳能电池、场效应晶体管、传感器件、纳米材料与器件中的应用。