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In recent years, perovskite solar cells (PSCs) have become a much charming photovoltaic technology and have triggered enormous studies worldwide, owing to their high efficiency, low cost and ease of preparation. The power conversion efficiency has rapidly increased by more than 6 times to the current 25.5% in the past decade. Hole transport materials (HTMs) are an indispensable part of PSCs, which great affect the efficiency, the cost and the stability of PSCs. Inorganic Cu-based p-type semiconductors are a kind of representative inorganic HTMs in PSCs due to their unique advantages of rich variety, low cost, excellent hole mobility, adjustable energy levels, good stability, low temperature and scalable processing ability. In this review, the research progress in new materials and the control of photoelectric properties of Cu-based inorganic HTMs were first summarized systematically. And then, concerning different processing methods, advances of the interface engineering of Cu-based hole transport layers (HTLs) in PSCs were detailly discussed. Finally, the challenges and future trends of Cu-based inorganic HTMs and their interface engineering in PSCs were analyzed.

An electroreflective modulator based on multiple-pass electroabsorption (EA) of coupled multiple quantum wells (CMQWs) is demonstrated for integration with low-loss polymer optical waveguides towards inter-chip and on-board optical interconnects at 850 nm. Taking advantage of coupling between quantum states in MQWs, the top polymer cladding and the bottom Au mirror form a Fabry–Perot cavity to further enhance the EA of CMQWs, thereby greatly improving the extinction ratio (ER) at a low voltage. The device achieves an ER of ∼6 dB and an insertion loss (IL)

Spontaneous growth in ambient environment has become an exciting topic issue for nanostructured materials. Here, hydrothermally synthesized zinc oxide (ZnO) nanorods loaded with detonation nanodiamonds (DNDs) enable a spontaneous structure evolution related to a catalytic reduction of solid phase carbon of DNDs, being different from the traditional carbonaceous carbon dioxide gas (CO2). Exposed to ambient environment from days to weeks, the original ZnO nanorods placed on silicon substrate transfer to a concentric core–shell structure of ZnCO3/ZnO including abundant Zn/DND nanoparticles. A coaxial configuration with periodical multi-layered walls is formed, when the surrounding CO2 concentration is increased arising from supporting amorphous carbon film beneath. Importantly, the ZnO/DND nanorods are directly dissociated into DND@Zn core–shell nanoparticles in CO2-rich environment. The structural evolution from ZnO nanorods is attributed to DND having catalytic, reducibility, and hydrophilic hierarchical porosity structure with the participations of CO2 and H2O in air. This work demonstrates that based on the combination of ZnO and DNDs, a spontaneous growth process occurs, which provides a strategy for fabrication of novel nanostructures (not limited to ZnO nanorods). Furthermore, it offers a possibility for degradation of greenhouse gases by enhancing capture and decomposition of CO2 in ambient environment for carbon neutral.

We propose and experimentally demonstrate a new photonics interconnect approach based on on-chip quadratic optical reflectors for interfacing a wide range of photonic devices. Here, we present its embodiments on compact waveguide bends and high performance fiber-to-chip optical couplers.

Coupling of light between different photonic devices, for example on-chip waveguides, fibers, and free-space optical elements, is an essential function enabling integrated optical systems. Efficient optical coupling demands matching the optical mode profiles and effective indices between two devices, and often changing propagation direction of the light. To date, such coupling is pre-dominantly accomplished via direct butt coupling of two devices, or meticulously optimized diffraction gratings. In this article, we present a new coupling scheme based on microfabricated free-form optical reflectors. The free-form reflector simultaneously achieves the functions of light beam re-directing and shaping (for mode matching), and can be versatilely adapted for coupling between photonic chips, fibers, and free-space surface-incident devices. We show that this technology uniquely fulfills all key performance requirements for optical interfaces with exceptionally low coupling loss (0.2–0.3 dB per coupler), large bandwidth (over half an octave), high density (large 2-D coupler arrays), polarization diversity, and superior alignment tolerance commensurate with passive alignment techniques. Preliminary experimental validation demonstrates waveguide-to-fiber coupling with a low insertion loss (IL) of 0.9 dB. We foresee that the technology will become a promising solution to the chip-level photonic interconnection and packaging challenges plaguing integrated photonics.

We have successfully synthesized 3D carbon nanotube foams through a simple self-assembly method. Taking these carbon nanotube foams as substrates, we have fabricated a novel core-shell structure of CNTF@CoO through a simple heat treatment process. The electrochemical measurements suggest that the composite has excellent electrochemical performances. It shows excellent rate properties and long-term cycling stability with a reversible capacity of about 820 mAh g−1 at the charge-discharge current density of 100 mA g−1. The capacity is as large as 448 mAh g−1 after 1000 cycles at 5000 mA g−1. The excellent performance can be attributed to the high capacity of CoO, the porous structure, and high conductivity of the carbon materials that provides fast ion transport pathways and relieves the strain during charge-discharge process.

We present a two-dimensional (2D) Si photonics optical phased array (OPA) using a serpentine design which eliminates the long directional couplers used in many 2D OPA designs. It significantly reduces the distance between the antenna benefitting far-field sidelobe reduction while maintaining high optical power use efficiency.

We have successfully prepared three dimensional carbon nanotube foams (CNTF) by a simple environmental-friendly method. However, the as-grown CNTF shows a high electrical conductivity but a reduced specific surface area which limits its application as electrode materials in energy storage devices. In this work, the as-grown CNTF has been activated by using certain concentration of KOH aqueous solution. The results indicate that activation can enlarge the specific surface area by producing new pores with sizes from micropore to macropore, but give no important change in shape and size of the CNTF. We take the activated CNTFs as electrodes for supercapacitors and lithium-ion batteries respectively, and find that activation can clearly enhance the specific capacities and rate properties due to the enhanced specific surface area and hierarchical porous structures. The activated three dimensional CNTF materials can also be used as supporters for other active materials indicating a potential application prospects.

Here we present next generation polymer-based singlemode waveguide devices and architectures for chip-scale photonic interconnections. A suite of optical devices are developed showing record low propagation loss, high-performance signal/power routing, and high-density inter-layer coupling. Flexible waveguide ribbons are further demonstrated that are widely applicable across chip- and board-domains.

Strategic manipulation of wave and particle transport in various media is the key driving force for modern information processing and communication. In a strongly scattering medium, waves and particles exhibit versatile transport characteristics such as localization, tunnelling with exponential decay, ballistic, and diffusion behaviours due to dynamical multiple scattering from strong scatters or impurities. Recent investigations of graphene have offered a unique approach, from a quantum point of view, to design the dispersion of electrons on demand, enabling relativistic massless Dirac quasiparticles, and thus inducing low-loss transport either ballistically or diffusively. Here, we report an experimental demonstration of an artificial phononic graphene tailored for surface phonons on a LiNbO3 integrated platform. The system exhibits Dirac quasiparticle-like transport, that is, pseudo-diffusion at the Dirac point, which gives rise to a thickness-independent temporal beating for transmitted pulses, an analogue of Zitterbewegung effects. The demonstrated fully integrated artificial phononic graphene platform here constitutes a step towards on-chip quantum simulators of graphene and unique monolithic electro-acoustic integrated circuits.

In this work, we report an anode material consisting of three-dimensional porous-carbon, nanometer-sized ZnO and Si nanoparticles to realize the high-performance lithium ion batteries. The composite powders are prepared following the processes of fabricating ZnO precursor by co-precipitation, hydrothermal reaction of mixed ZnO/SiO/porous-carbon powders, and subsequent neutralization and roast treatments. Using the hybrid anode material, the enhanced capacity performance (more than 900 mA h g−1 at 0.2 C after 300 cycles) and remarkable long-term cycle stability (more than 500 mA h g−1 at 2 C after 300 cycles) are achieved, which are significantly higher than that of using ZnO or graphite alone as anode. The improvement is ascribed to the synergistic effect of the highly conductive and large surface area porous-carbon, three-dimensional ZnO nanorods, and high adsorption of Li+ of Si particles.

We report a novel anode consisting of detonation nanodiamond, SiOx nanoparticals and carbon nanosheets, to achieve high performance lithium-ion batteries. In the process of charge and discharge, the lithium ion batteries using the prepared nanocomposite anode show remarkable capacity performance with a specific capacity of 1182 mA h g−1 at a constant current of 100 mA g−1 after 100 cycles. With further increasing the current to 1000 mA g−1, a high specific capacity of 622 mA h g−1 can be realized after 750 cycles, indicating a superior long-term cycle stability. The improvement of cycle stability and specific capacity can be attributed to the introduction of nanodiamond to form an effective buffer structure and efficient Li+ transport pathway.

The intralaminar and interlaminar damages of U3160/3266 laminated composites toughened by polyamide nonwoven fabric (PNF) under low velocity impact are investigated through a numerical model which considers both the three-dimensional continuum damage mechanics (CDM) and the bilinear cohesive zone model (CZM). The analysis of the intralaminar damage is implemented by the ABAQUS/Explicit finite element code coupled with a user-defined subroutine VUMAT where the longitudinal failure, transverse matrix cracking, and nonlinear shear of the material are taken into account. Then the effects of the thickness and strength of PNF/3266 interlayer on the damage of composites are numerically analyzed. The results reveal that damage morphology can be simulated qualitatively compared to the experimental counterparts. With the decreasing interlayer thickness or the increasing interlayer strength, the damage area is effectively reduced. This work provides an effective model to predict the low velocity impact damage of composites, and is helpful for the optimization of interlayer toughened composites. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

The objective of this research is to put forward a toughening method by using the polyamide non-woven fabric (PNF) and investigate the Mode-I fracture toughness and delamination characteristic of the toughened CFRP laminates by performing the double cantilever beam test. The effect of PNF interlayer, which is formulated by a bilinear cohesive zone model, on the Mode-I fracture of U3160-PNF/3266 laminated composites is numerically analyzed. And the intralaminar damages are considered by using strength criteria and stiffness degradation law. The influences of PNF/3266 interlayer strength, U3160/3266 laminate thickness and initial crack length on the mechanical response of laminates are studied systematically. The work by combining the experiment and simulation is helpful for the optimal design of laminated composites used in aerospace and civil engineering.

Based on the continuum damage mechanics (CDM) and the cohesive zone model (CZM), a numerical analysis method for the evaluation of damage in composite laminates under low-velocity impact is proposed. The intraply damage including matrix crack and fiber fracture is represented by the CDM which takes into account the progressive failure behavior in the ply, using the damage variable to describe the intraply damage state. The delamination is characterized by a special contact law including the CZM which takes into account the normal crack and the tangential slip. The effect of the interlaminar toughness on the impact damage is investigated, which is as yet seldom discussed in detail. The results reveal that as the interlaminar fracture toughness enhances, the delamination area and the dissipated energy caused by delamination decrease. The contribution of normal crack and tangential slip to delamination is evaluated numerically, and the later one is the dominant delamination type during the impact process. Meanwhile, the numerical prediction has a good agreement with the experimental results. The study is helpful for the optimal design and application of composite laminates, especially for the design of interlaminar toughness according to certain requirements. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers

A resin transfer molding technique was used to fabricate thick-walled composite connecting rods, and then the mechanical performance of the connecting rod was studied experimentally, at the same time the stress and failure index distributions were simulated numerically. The experimental results show that under a tensile load, the connecting rod first cracks near the vertex of the triangle areas at the two ends, and then the damage propagates along the interface between the main bearing beam and the triangle area as well as along the round angle of the triangle area. Whereas under a compressive load, the delamination primarily occurs at the corner of the U-shaped flange, and the final destruction is caused by the fracture of fibers in the main bearing beam. The simulated results reveal that the tensile failure is originated from the delamination at the round angle transition areas of the T-joints, and the failure strength is determined by the interlaminar strength. Whereas the compressive failure is caused by the fracture of fibers in the main bearing beam, and the failure strength of the structure is determined by the longitudinal compressive strength of the composite material. The simulated results are basically consistent with the experimental results. Hence the mechanical performance and failure mechanism of the complicated composite structure are revealed in great detail through the coupling of the two kinds of research methods, which is helpful for the optimal design of composite structures.

A constitutive model is constructed to consider the resin matrix post-yield softening and progressive hardening behaviors. A user-defined material mechanical behavior (UMAT) subroutine is created, then the non-linear three-dimensional finite element analysis on the tensile processes of multi-fiber composites is conducted. The approximate 45° shear bands emanating from the matrix crack tip are found, being coincided with the experimental observations. The shear stress on the adjacent intact fiber/matrix interface is strongly influenced by the shear band and thus the stress concentration factor (SCF) changes obviously in the adjacent fibers. The distinct stress redistribution in the adjacent intact fibers implies the significant effect of the shear bands on the progressive fiber fracture initiation. As the inter-fiber spacing increases, the peak value of the SCF in the adjacent intact fiber decreases, whereas the overload zone becomes wider. The research has provided a helpful tool to evaluate the failure of fiber composites and optimize the composite performance through the proper selection of resin matrix properties and fiber volume fraction.

We analyze a chip-to-chip optical interconnect platform based on our recently developed flexible substrate integration technology. We show that the architecture achieves high bandwidth density (100 Tbs/cm2), and does not require optical alignment during packaging. These advantages make the flexible photonics platform a promising solution for chip-to-chip optical interconnects. We further report initial experimental characterizations of the flexible photonics platform fabricated using thermal nanoimprint patterning of glass waveguides and III-V die bonding.

A compact integrated optical submodule for the application of 40 G parallel short reach optical interconnects systems is demonstrated. The submodule utilizes a silicon optical bench to integrate all optical components and to realize passive fiber array alignment enabled by high-precision silicon processing technologies. The submodule is capable of transmitting and receiving data at 40 Gb/s rate up to a few hundred meters using multimode fibers. This production-ready platform can be scaled to 100 Gb/s and beyond.

A new numerical simulation method was proposed to predict the mechanical behavior of carbon fiber reinforced resin composites under low-velocity impact load. The impact damage evolution can be characterized in the form of energy dissipation which can be calculated through the new numerical model. The evolution mechanism of delamination was analyzed through distinguishing between the normal induced delamination and tangential slip induced delamination. The drop weight tests were conducted on composite laminates with five kinds of stacking sequence. Experimental analysis was also presented in this article. The damage area and distribution was investigated through ultrasonic C-scan. The prediction had a good agreement with the experimental results through the comparison of impact response. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44374.

A SiGe-on-SOI carrier-depletion Mach-Zehnder modulator is presented. Compared with Si modulators, it eliminates advanced lithography by enabling a dual-waveguide design using small SiGe waveguides for modulators and large Si waveguides for edge coupling. DC and high speed test results are included.

A III-V on Si hybrid integration is demonstrated by using Si slab waveguides with two parabolic reflective facets to increase the alignment tolerance between flip-chip bonded lasers and modulators. DC and high speed test results of the integrated transmitter are included.

A SiGe-on-SOI carrier-depletion Mach-Zehnder modulator is presented. Compared with Si modulators, it enables a dual-waveguide design using small SiGe waveguides for modulators and large Si waveguides for edge coupling thus eliminates advanced lithography for inverse tapers. DC and high speed test results are included.

Electronic–photonic synergy has become an increasingly clear solution to enhance the bandwidth and improve the energy efficiency of information systems. Monolithic integration of optoelectronic devices is the ideal solution for large-scale electronic–photonic synergy. Due to its pseudo-direct gap behavior in optoelectronic properties and compatibility with Si electronics, epitaxial Ge-on-Si has become an attractive solution for monolithic optoelectronics. In this paper we will review recent progress in Ge-on-Si optoelectronics, including photodetectors, electroabsorption modulators, and lasers. The performance of these devices has been enhanced by band-engineering such as tensile strain and n-type doping, which transforms Ge towards a direct gap material. Selective growth reduces defect density and facilitates monolithic integration at the same time. Ge-on-Si photodetectors have approached or exceeded the performance of their III–V counterparts, with bandwidth-efficiency product > 30 GHz for p-i-n photodiodes and bandwidth-gain product > 340 GHz for avalanche photodiodes. Enhanced Franz–Keldysh effect in tensile-strained Ge offers ultralow energy photonic modulation with 100 GHz intrinsic bandwidth. Room temperature optically-pumped lasing as well as electroluminescence has also been achieved from the direct gap transition of band-engineered Ge-on-Si waveguides. These results indicate that band-engineered Ge-on-Si is promising to achieve monolithic active optoelectronic devices on a Si platform.

Electronic-photonic synergy has become an increasingly clear solution to enhance the bandwidth and improve the energy efficiency of information systems. Monolithic lasers on silicon are ideal for large scale electronic-photonic integration. Germanium is a particularly interesting candidate for this application due to its pseudo-direct gap behavior in the near infrared regime for optical communications and compatibility with advanced silicon complementary metal oxide semiconductor (CMOS) technology. In this paper, we review theoretical modeling and experimental studies on optical gain and lasing from monolithic epitaxial Ge-on-Si devices band-engineered by tensile strain and n-type doping to compensate the energy difference between the direct and indirect conduction valleys. Demonstrations of optical gain and lasing at room temperature indicate that the Ge-on-Si laser is a promising candidate for monolithic electronic-photonic integrated circuits.

It has been demonstrated theoretically and experimentally that germanium, with proper strain engineering and n-type doping, can be an efficient light emitter and a gain medium at its direct bandgap within the third optical communication window ( ~1520-1620 nm). In this paper, we systematically discuss the effect of strain, doping, and temperature on the direct-gap optical gain in germanium. For electrically pumped devices, properties and design guidelines of Ge/Si heterojunction are also analyzed and compared with the results from fabricated Ge/Si heterojunction LEDs.

Thin film Ge on Si is a potential active material candidate for electrically pumped monolithically integrated Si-based light emitters. Theoretical analysis has shown that a combination of strain and n-type doping can modify the band structure of Ge so that it exhibits direct bandgap properties. Direct band-to- band optical transition is observed from the room temperature photoluminescence at around 1550nm. An optical bleaching ef- fect occurring in lock-in pump-probe measurements indicates a precursor to optical net gain.

A compact parallel optical engine platform using Si optical bench technology to realize highly manufacturable vertical coaxial alignment approach is demonstrated and an in-production 40G optical engine using this platform is presented.

Selenium dioxide nanowires were fabricated as the co-products of ZnSe nanostructures. The SeO2 nanowires have diameters between 20∼70 nm and lengths up to several hundred micrometers. The morphology and microstructure of the nanowires were analyzed using TEM, and the growth mechanism of the SeO2 nanowires was explained under the framework of a vapor-solid model, in which structure defects may play a very important role in the nanowire growth. The nanostructured SeO2 materials may find application in both catalytic and biological fields.

ZnO nanorod arrays have been grown on glass substrates. X-ray diffraction demonstrated that most of the nanorods in the arrays are of wurtzite crystal structure with preferable [0 0 1] growth direction. The morphology and the microstructure of the arrays and the nanorods were investigated by using scanning electron microscopy and transmission electron microscopy. A wetting layer of ZnO was observed between the nanorods and the substrate. On the (0 0 1) surfaces of some nanorods, the initial stage of nucleation and the subsequent development of the nuclei were observed, revealing the process of the nanorod growth. Electron energy-dispersive X-ray spectroscopy revealed that the wetting layer and the nanorods exhibit different stoichiometric ratio. The kinetics of the formation of the structures was discussed within the framework of the Stranski–Krastanov mechanism. In addition, photoluminescence spectra of the as-grown ZnO nanorod arrays indicate their possible applications in ultraviolet (UV) emission devices.

ZnO nanorod arrays with peculiar morphologies were synthesized on (111)-oriented Si substrate and glass via a vapor phase growth. The morphology of the individual nanorod can be flat-headed bottle-like, and needle-like, which depends on the deposition positions relative to the source materials in the presence of a controlling element Se. In addition, the arrays of all the three morphologies exhibit good alignment and high coverage. This fabrication technique can be also used to direct the controllable growth of other nanomaterials with similar morphologies.

We report an above-band-gap radiative transition in the photoluminescence spectra of single crystalline Ge in the temperature range of 20~296 K. The temperature-independence of the peak position at ~0.74 eV is remarkably different from the behavior of direct and indirect gap transitions in Ge. This transition is observed in n-type, p-type, and intrinsic single crystal Ge alike, and its intensity decreases with the increase of temperature with a small activation energy of 56 meV. Some aspects of the transition are analogous to III-V semiconductors with dilute nitrogen doping, which suggests that the origin could be related to an isoelectronic defect.

Well-aligned arrays of ZnO nanoneedles were fabricated using a simple vapor phase growth. The diameters of the nanoneedle tips are as small as several nanometers, which is highly in favor of the field emission. Field-emission measurements using the nanoneedle arrays as cathode showed emission current density as high as 2.4 mA/cm2 under the field of 7 V/μm, and a very low turn-on field of 2.4 V/μm. Such a high emission current density is attributed to the high aspect ratio of the nanoneedles. The high emission current density, high stability, and low turn-on field make the ZnO nanoneedle arrays one of the promising candidates for field-emission displays.

Stoichiometric ZnSe nanowires have been synthesized through a vapor phase reaction of zinc and selenium powder on the (100) silicon substrate coated with a gold film of 2 nm in thickness. The microstructures and the chemical compositions of the as-grown nanowires have been investigated by means of electron microscopy, the energy dispersive spectroscopy, and Raman spectroscopy. The results reveal that the as-grown materials consist of ZnSe nanowires with diameters ranging from 5 to 50 nm. Photoluminescence of the sample demonstrates a strong green emission from room temperature down to 10 K. This is attributed to the recombination of electrons from conduction band to the medium deep Au acceptors.

To meet the unprecedented demands for data transmission speed and bandwidth silicon integrated photonics that can generate, modulate, process and detect light signals is being developed. Integrated silicon photonics that can be built using existing CMOS fabrication facilities offers the tantalizing prospect of a scalable and cost-efficient solution to replace electrical interconnects. Silicon, together with commonly used dielectric materials in CMOS processes such as silicon dioxide, is a great material system for optical confinement and wave transmission in near infrared range. However, silicon is not a good choice for active photonic devices due to its transparency in such wavelength range. Germanium and GeSi alloy, the materials that have long been adopted to improve the performance of silicon transistors in many ways, have been showing their potential as the building blocks of such active integrated optical devices. This chapter discusses the research of using germanium and GeSi for silicon-integrated photodetection and light source in the contexts of material physics and growth, device design and fabrication. This introduction section briefly introduces the background of integrated silicon photonics and some germanium properties which are important for photonic applications. Next section focuses on waveguide-integrated germanium photodetectors which can readily be integrated with silicon waveguide on mature silicon or silicon-on-insulator (SOI) platform. The physics and design considerations of these devices are presented with details. The fabrication processes of these devices are also discussed with some extent. Next section includes a newly developed field that using germanium for light sources in silicon photonics applications such as light-emitting-diodes (LEDs) and lasers. There has been a few breakthroughs in this topic including the author’s work of epitaxial germanium LEDs and optically pumped lasers operating at room temperature. The physics of this unusual concept of using indirect band gap material for light emission is discussed in details and some important results are presented.

We report optically-pumped Ge-on-Si lasers with direct gap emission near 1600 nm at room temperature. The Ge-on-Si material was band-engineered by tensile strain and n-type doping to compensate the energy difference between direct and indirect band gaps for efficient light emission. Modeling of Ge/Si double heterojunction LEDs shows that it is possible to achieve >10% quantum efficiency even assuming an Auger coefficient 10 times larger than reports in literature. Edge-emitting Ge-on-Si waveguide LEDs have also been demonstrated at room temperature. These simulation and experimental results strongly indicate the feasibility of electrically-pumped Ge-on-Si lasers.

We report room temperature Ge-on-Si lasers with direct gap emission at 1590–1610 nm. Modeling of Ge/Si double heterojunction structures, which is supported by experimental results of Ge/Si LEDs, indicates the feasibility of electrically pumped lasers.

Monolithic lasers on Si are ideal for high-volume and large-scale electronic-photonic integration. Ge is an interesting candidate owing to its pseudodirect gap properties and compatibility with Si complementary metal oxide semiconductor technology. Recently we have demonstrated room-temperature photoluminescence, electroluminescence, and optical gain from the direct gap transition of band-engineered Ge-on-Si using tensile strain and n-type doping. Here we report what we believe to be the first experimental observation of lasing from the direct gap transition of Ge-on-Si at room temperature using an edge-emitting waveguide device. The emission exhibited a gain spectrum of 1590-1610 nm, line narrowing and polarization evolution from a mixed TE/TM to predominantly TE with increasing gain, and a clear threshold behavior.

We report the design and fabrication of a novel multispectral photodetector capable of detecting multiple wavebands in a single pixel. Our prototypical device demonstrates spectral selectivity with a peak responsivity of 65.4V/W at 3.9μm wavelength.

A multi-wavelength receiver was fabricated on SOI using a monolithically integrated arrayed waveguide grating (AWG) and 32 germanium waveguide photodetectors. The CMOS compatible high-speed detectors are capable for OC-192 or 10Gb/s data rate.

We demonstrate monolithic Ge-on-Si lasers, band-engineered by tensile strain and n-type doing, that exhibit direct gap emission around 1600 nm at room temperature. Direct gap electroluminescence from heterojunction devices verifies the feasibility of electrical pumping.

We report direct band gap optical gain of tensile strained n+ epitaxial Ge-on-Si at room temperature, which confirms that band-engineered Ge-on-Si is a promising gain medium for monolithic optical amplifiers and lasers on Si.

We report the design, fabrication, and characterization of spectral selective mid-infrared PbTe photodetector pixels monolithically integrated on a silicon platform. We demonstrate spectral selectivity with a peak responsivity of 65.4V/W.

Some of the crucial building blocks for Si photonics are high performance photodetectors, modulators, and efficient light sources. High quality Ge epitaxial films on Si have opened new possibilities for high performance CMOS compatible devices.

We demonstrate room temperature photoluminescence and optical gain from the direct band gap transition of tensile strained n-type Ge-on-Si around 1600 nm, which can be applied to a Si-based laser for optical interconnects and communications.

We report experimental observation of direct band gap photoluminescence (PL) and optical bleaching of band-engineered epitaxial Ge-on-Si at room temperature, confirming that this material is a promising candidate for efficient light emitting devices on Si.

Optical gain and net material gain via direct bandgap transition at around 1550nm of the tensile-strain band-engineered n-type Ge has been analyzed. Photoluminescence spectra measured at room temperature confirm the theoretical predictions.

We demonstrate and characterize both one-dimensional photonic crystal monolithically integrated on a Si platform, and thermally evaporated PbTe film with room temperature photoconductivity, which are key components for low cost resonant-cavity-enhanced mid-infrared photodetectors.