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An integrated tunable double sideband suppressor based on a two-rings-assisted Mach Zehnder interferometer is presented for remote optical carrier reuse. We demonstrate a suppression ratio more than 15 dB for both 28GHz and 39GHz mmWave transmission.

We propose and demonstrate a novel Si/Si 3 N 4 composite waveguide structure potentially for implementing low-loss and high-speed photonic integrated circuits. The measured waveguide propagation loss is 0.46 dB/cm.

We present an asymmetric dual-level grating coupler fabricated on an ultra-thin Si/Si 3 N 4 composite photonics platform to achieve a high coupling efficiency for light coupled from a single-mode fiber to the waveguide and vice versa.

A miniaturized mmWave-over-fiber remote radio head implemented by heterogeneous integration of Si photonics and CMOS integrated circuits is presented. A 28-GHz, 16-QAM OFDM signal is transmitted through this module with EVM 9.52%.

Here, an efficient intracellular delivery of molecules with high cell viability is reported using nanosecond-pulsed laser-activated plasmonic photoporation, mediated by high-aspect-ratio nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles (nm-AuPNPs) at near-infrared wavelength. Upon pulsed laser illumination, nm-AuPNPs exhibit greater plasmonic extinction than spherical AuPNPs, which increase their energy efficiency and reduce the necessary illumination of light, effectively controlling cell damage and improving the delivery efficiency. Nm-AuPNPs exhibit surface plasmon absorption at near infrared region with a peak at 945 nm. Pulsed laser illumination at this plasmon peak triggers explosive nanobubbles, which create transient membrane pores, allowing the delivery of dyes, quantum dots and plasmids into the different cell types. The results can be tuned by laser fluence, exposure time, molecular size and concentration of nm-AuPNPs. The best results are found for CL1-0 cells, which yielded a 94% intracellular PI dye uptake and ∼100% cell viability at 35 mJ cm−2 laser fluence for 945 nm wavelength. Thus, the presented approach has proven to have an inevitable potential for biological cell research and therapeutic applications.

Optomechanics of colloidal microparticles has wide applications in biological analysis and sensing. For colloidal microspheres or microdroplets, the optomechanical force can be magnified through the cavity enhancement effect. However, it is difficult to analyze the force since the colloidal microspheres are suspended in liquid, and addressing a movable microsphere at a specific position in three-dimensional space is also challenging. An on-chip integrated operating platform comprising waveguides and microelectromechanical systems is employed to study the cavity-enhanced optical gradient force on colloidal microspheres, owing to the ability to precisely control the distance between a suspended microsphere and a waveguide through dielectrophoretic force. We introduce two kinds of optomechanical coupling mechanisms at resonance, depending on the initial coupling gap without inclusion of the optical gradient force. One is self-adjusted coupling, where the coupling gap of a suspended microsphere continuously varies with the optical input power, and the other is bistable coupling, where the coupling gap hops from one state to the other as the input power exceeds over a threshold value, which is caused by the nature of nonlinear gap-dependent optical gradient force.

In this paper, we present an ultra-sensitive photonic refractive index (RI) sensor based on nanoporous silicon (NPS) one-dimensional (1D) microcavity structures for detecting heavy metal ions in water. Consisting of two distributed Bragg reflectors (DBR) symmetrically placed about a defect layer fabricated by successive electrochemical etchings (ECE), the 1D microcavity is employed to enhance the sensitivity of the sensors. Although these RI sensors possess the property of high sensitivity to RI change and high resolution due to high porosity and narrow resonance peak, respectively, however their selectivities to analytes are poor, and limit of detections (LOD) are also restricted owning to passive interaction between analytes and sensors. To solve these problems, we propose a new procedure for heavy metal ion detection that offers good selectivity and ultra-low LOD while keeping the advantages in sensitivity and resolution of the NPS sensor. In the procedure, an electrochemical reduction process is applied to actively/selectively pre-concentrate and reduce metal ions on the pore surfaces of the NPS that results in the improvement in selectivity and LOD. This ECA-NPS based photonic sensor was applied to detect cadmium ions in deionized water revealing a sensitivity of 342 nm/RIU and 0.152 ppb of LOD in DI water. LOD as low as 1.16 ppb with a selectivity over sodium, potassium, magnesium, calcium and nickel etc, has also been demonstrated with a longer reduction time of 20 min for 10 ppb cadmium ions spiked in lake water.

Metal-semiconductor-metal (MSM) photodetectors made of gallium antimonide (GaSb) on silicon waveguides by the rapid melt growth method are investigated. By controlling the thermodynamics of crystal regrowth and optimizing the process condition, single-crystal GaSb stripes are monolithically integrated on the silicon substrate. The MSM GaSb waveguide photodetector shows a responsivity of 0.57 A/W at 1550 nm.

We studied using rapid melt growth (RMG) method to make GaSb microdisks on Si substrate. By optimizing the process condition, we observe a strong photoluminescence.

The efficient monolithic III-V integration on silicon (Si) substrates can leverage the excellent optoelectronic properties of III-V semiconductors and the Si microfabrication technology for electronic, optoelectronics, integrated photonics devices. However, the origin of the interfacial and material defects during III-V monolithic integration on Si poses the challenge to achieve efficient optical emitters, detectors. In this study, we investigated different surface treatment schemes before rapid melt growth (RMG) of GaSb on Si substrate to attain defect control. The deposition of an Sb layer (10 nm) on GaSb precursors surfaces resulted in achieving better structural and optical properties of GaSb post RMG. We achieved a reduction of 2.48 atomic % of unintentional incorporation of Si into the GaSb via Sb treatment compared to that of untreated GaSb analysed using transmission electron microscopy and energy-dispersive X-ray spectroscopy. Improved surface morphology with reduced root mean square roughness of 3.7 nm is obtained with Sb layer treatment compared to 5.6 nm for untreated GaSb precursor measured by atomic force microscopy. We obtained improved optical properties and low defect density with an in-situ Sb treatment scheme on GaSb precursor surface by µ-Photoluminescence and µ-Raman spectroscopy analysis.

We propose an interdigitated Si lateral bipolar phototransistor integrated with an Al-SiO 2 -Al (metal-dielectric-metal structure) visible-blind ultraviolet Fabry-Perot bandpass filter. The maximum optical transmittance is 0.56 at the wavelength 332 nm, and the FWHM of transmission is 78.6 nm. And we successfully demonstrated suppression of visible light with the highest responsivity $\mathbf{9.78} \times \mathbf{10}^{-\mathbf{2}}$ (A/W) at wavelength of 350 nm.

A new Au-SiO2-Si stack grating structure to efficiently couple normally incident light to Au-Ge surface plasmon modes for enhancing Ge surface absorption is presented. Through an optimized design on the grating dimension, the surface plasmon modes are hybridized with a cavity mode for both suppressing light reflection and transmission to the Ge substrate. About 70% Ge absorption occurs in a 0.15-μm shallow layer near the Ge surface at the wavelength of 1.38 μm. Such a short absorption length is desirable for implementing a low-noised Ge avalanche photodiode.

We report a wafer-scale fabrication process to make large-area slot antenna arrays for studying spontaneous emission enhancement of 2D transition metal dichalcogenide. The experimental results show a 10-fold enhancement of photoluminescence was observed.

We present a butt-coupled Germanium (Ge) metal-semiconductor-metal photodetectors on silicon (Si) waveguides. This device is implemented by a novel process using self-aligned microbonding technique and rapid-melt-growth method for monolithically integrating single-crystal Ge and Si devices on the same plane. Through inserting a thin amorphous Si (a-Si) layer between the Ge and metal contact, the Schottky barrier height is modulated, which effectively reduces the dark current and increases the operation speed. The fabricated device shows a low dark current of 0.24 μA, a 3 dB bandwidth of 15 GHz and a responsivity of 0.25 A/W, at a bias voltage of -2.6 V for wavelength 1310 nm.

A silicon avalanche photodetector with a low breakdown voltage of -6.78 V is demonstrated by narrowing down the intrinsic layer width of interdigitated p-i-n junctions to ~ 150 nm. It reaches the physical limit of avalanche breakdown in which the performance degradation caused by the Zener tunneling process is negligible. Dark current at -4 V is measured, and a responsivity (gain) exceeding 1.424 A/W (110) at -6.75 V is obtained with an 850-nm laser illumination. The intrinsic bandwidth is determined to be 10 GHz, suggesting our device is applicable for a 10-Gb/s high-speed optical receiver application and beyond.

For present-day optical communication systems, the commonly used normal-incidence photodetectors suffer from the tradeoff between bandwidth and quantum efficiency. Such a tradeoff is especially adverse for long wavelength communication systems operating at higher data rates. For example, the maximum responsivity for a commercially available 25 Gbps photodetector operating at 1310 nm wavelength is limited to less than 0.8 A/W. In this work, we design and demonstrate a high-speed, backside-incidence, critically-coupled Ge on SOI photodetector operating at 1310 nm while maintaining a high quantum efficiency. Our device is fabricated with RPCVD epitaxy, i-line lithography, silicide contact, and Al metal wire, which are fully compatible with the state-of-art CMOS process technology. With our epitaxial scheme and surface passivation method, a low bulk (surface) dark current density of 13 mA/cm2 (0.79 μA/cm) is measured from a ~ 700 nm thick Ge p-i-n device at -1 V bias. The responsivity at 1310 nm wavelength is measured to be 0.87 A/W, and the 3dB optical bandwidth of a 20 μm diameter device is measured to be 26 GHz. Our high-speed, backside-incidence, critically-coupled Ge on SOI photodetector may serve as a high-performance and low-cost solution for next generation high-speed optical receivers, and its benefit of decoupling bandwidth and quantum efficiency is especially prominent at higher data rates such as 40 Gbps and beyond.

We propose wavelength-selective infrared sensors made by multiple metallic resonant waveguide gratings integrated on a germanium photodetector array. The detective spectrum can cover from 1.25μm to 1.55μm with the FWHM less than 25nm.

A low-voltage dual-drive push-pull Si Mach-Zehnder modulator is demonstrated to implement an optical 25 Gbaud (50 Gb/s) PAM-4 transmission.

A new technology using hydrogen annealing and thermal oxidation is proposed to fabricate a very compact 2-D multimode interference coupler monolithically integrated with two-layer silicon photonic wires. Two devices, a 1 × 1 cross-power coupler and a 1 × 22 power splitter, are presented and characterized. The experimental result shows that a 3-dB transmission bandwidth of 1.1 nm, and the on-chip coupler losses of 8.6 dB and 2.84 dB were accomplished for the 1 × 1 cross-power coupler and the 1 × 22 power splitter. This paper demonstrates the possibility of realizing 3-D photonic integration for silicon-on-insulator lightwave circuits.

Poor electron injection is a great concern for organic light emitting diodes (OLEDs). In order to improve the electron mobility, inserting organic superlattice structures in the electron transport layer was investigated in conventional OLEDs configuration. The superlattices are composed of alternating tris(8-hydroxyquinoline aluminium (Alq3) and copper phthalocyanine (CuPc) thin films, which are used as electron and hole injection layers. Experimental results show superlattices with a 6-nm period have the largest injected current. Reduction of turn-on voltage and resistance of superlattice OLEDs were also observed. After thermal annealing, the current-voltage characteristic changes and shows the possibility of layer intermixing in organic superlattices.

A single crystalline silicon microtoroidal resonator with integrated MEMS-actuated tunable optical coupler is demonstrated for the first time. It is fabricated by combining hydrogen annealing and wafer bonding processes. The device operates in all three coupling regimes: under-, critical, and over-coupling. We have also developed a comprehensive model based on time-domain coupling theory. The experimental and theoretical results agree very well. The quality factor (Q) is extracted by fitting the experimental curve with the model. The unloaded Q is as high as 110 000, and the loaded Q is continuously tunable from 110 000 to 5400. The extinction ratio of the transmittance is 22.4 dB. This device can be used as a building block of resonator-based reconfigurable photonic integrated circuits

A new plasmonic grating structure is proposed to implement Si near-infrared photodiodes through plasmon-induced hot carrier injection. The power conversion efficiencies (photon-to-plasmon) are near 70% and 90% at the wavelength of 851nm and 1305nm, respectively.

Near-infrared absorption at 2000-nm wavelength is observed in a Ge 1−x Sn x metal-semiconductor-metal (MSM) photodetector on a Si substrate. The device is fabricated by rapid melt growth method with graded Sn concentration up to 5–10%.

A GeSn metal-semiconductor-metal (MSM) photodetector is fabricated on a silicon-on-insulator (SOI) waveguide by rapid melt growth method. The Sn concentration of the GeSn photodetector is 2 % and shows a larger photo-responsivity by comparing with a pure Ge photodetector at long wavelength. The dark current is 3.7e-7 A at 5.4 V and the operation speed can be as high as 6.2 GHz.

A fast, effective process using hydrogen annealing is introduced to perform profile transformation on silicon-on-insulator (SOI) and to reduce sidewall roughness on silicon surfaces. By controlling the dimensions of as-etched structures, microspheres with 1 /spl mu/m radii, submicron wires with 0.5 /spl mu/m radii, and a microdisk toroid with 0.2 /spl mu/m toroidal radius have been successfully demonstrated on SOI substrates. Utilizing this technique, we also observe the root-mean-square (rms) sidewall roughness dramatically reduced from 20 to 0.26 nm. A theoretical model is presented to analyze the profile transformation, and experimental results show this process can be engineered by several parameters including temperature, pressure, and time.

A polarization-selective fiber-to-silicon waveguide coupler made by an SU-8 prism as well as a micrograting is demonstrated. The size of the SU-8 prism well matches the core dimension of a single-mode fiber to increase the coupling efficiency, and the micrograting provides the selectivity of polarization mode coupling. Only the TE wave is able to be coupled to the silicon waveguide. The measured coupling loss of the SU-8 prism and the micrograting is 4.5 dB. The polarization extinction ratio is 20 dB. The fiber misalignment tolerances are 2 and 3 μ m for the x- (lateral) and y- (vertical) directions, respectively, according to a transmission window of 3-dB drop.

An image-controlled dielectrophoretic (ODEP) optofluidic system is demonstrated to manipulate microsphere resonators in an aqueous medium. Through this platform we can freely position the microshere resonator near a waveguide to manage the coupling condition. The spectral analysis shows the microsphere resonator can be operated in the under-coupling, critical coupling and over-coupling regimes.

GeSi based photodetectors and avalanche photodetectors on silicon photonics platform have been widely studied in the past decade due to its low cost nature and compatibility with CMOS fabrication process. Conventionally, high-quality Ge on Si is obtained by a direct epitaxy growth or by a wafer/die bonding technique, which complicates the possible on-chip integration with CMOS electronics such as transimpedance amplifier, equalizer and limiting amplifier etc. Recently, rapid-melt growth of Ge on insulator emerged as a new method to produce high-quality Ge stripes. In this paper, we present our effort in making waveguide based photodetectors and avalanche photodetectors using Ge rapid-melt growth. First, we demonstrate a high-performance, high-speed GeSi heterojunction photodiode by a self-aligned microbonding technique utilizing surface tension. Such a method is subsequently extended to fabricate a novel butt-coupled, high-speed metal-semiconductor-metal Ge photodetector. At the same time, we study the possibility of operating GeSi avalanche photodetectors at a low bias voltage to be compatible with standard CMOS IC power supply. Based on the theoretical and numerical results, a new type of GeSi avalanche photodetector in three-terminal configuration is proposed and demonstrated, reaching the lowest possible operation bias voltage constrained by Zener tunneling breakdown.

A compact guided-wave optical switch is realized by integrating one-dimensional photonic crystals with microelectromechanical systems (MEMS) actuators. The ON-OFF switching is achieved by physically moving a photonic crystal defect. Experimental results show an extinction ratio of 11 dB at 1.56-/spl mu/m wavelength and a 0.5-ms time constant of the step response.

A high speed Si modulator with fringe field junctions is presented. Low carrier absorption (1.3 dB/mm) and Vπ L (1.8 V-cm) are demonstrated. The measured modulation speed and depth are 11.8-GHz and 8-dB.

A novel tunable microdisk resonator with microelectromechanical-system (MEMS)-actuated deformable waveguides is demonstrated for the first time. The deformable waveguide enables us to continuously vary the power coupling ratio of the microdisks. A laterally coupled device with a quality factor of 7700 is fabricated on silicon-on-insulator substrate. An optical notch filter with variable attenuation at the resonant wavelength is successfully demonstrated, with an extinction ratio of 9 dB. The MEMS-actuated tunable microdisk is a basic building block for many dynamic wavelength-division-multiplexing circuits.

A novel technique using surface tension to locally bond germanium (Ge) on silicon (Si) is presented for fabricating high performance Ge/Si photodiodes. Surface tension is a cohesive force among liquid molecules that tends to bring contiguous objects in contact to maintain a minimum surface energy. We take advantage of this phenomenon to fabricate a heterojunction optoelectronic device where the lattice constants of joined semiconductors are different. A high-speed Ge/Si heterojunction waveguide photodiode is presented by microbonding a beam-shaped Ge, first grown by rapid-melt-growth (RMG) method, on top of a Si waveguide via surface tension. Excellent device performances such as an operating bandwidth of 17 GHz and a responsivity of 0.66 and 0.70 A/W at the reverse bias of −4 and −6 V, respectively, are demonstrated. This technique can be simply implemented via modern complementary metal-oxide-semiconductor (CMOS) fabrication technologies for integrating Ge on Si devices.

A novel process using self-aligned microbonding technique for Ge butt-coupled to silicon waveguides is presented. The photodetector features a low dark current of 0.29 μA and a high responsivity of 1.01 A/W at 1310 nm at -1 V bias.

This investigation reports observations of optical bistability in a silicon nitride (SiN) micro-ring resonator with azo dye-doped liquid crystal cladding. The refractive index of the cladding can be changed by switching the liquid crystal between nematic (NLC) and photo-induced isotropic (PHI) states by. Both the NLC and the PHI states can be maintained for many hours, and can be rapidly switched from one state to the other by photo-induced isomerization using 532 nm and 408 nm addressing light, respectively. The proposed device exhibits optical bistable switching of the resonance wavelength without sustained use of a power source. It has a 1.9 nm maximum spectral shift with a Q-factor of over 10000. The hybrid SiN- LC micro-ring resonator possesses easy switching, long memory, and low power consumption. It therefore has the potential to be used in signal processing elements and switching elements in optically integrated circuits.

Strong transverse magneto-optical Kerr effect (TMOKE) on Au/Fe/Au surface plasmon (SP) gratings is demonstrated. Via the optimal design of this structure, the measured Kerr parameter is 0.03, which is 3 times larger than the maximal value ever reported on a plane magneto-optical SP substrate. Moreover, the Kerr parameter is very dispersive near the SP wavelength, which can be used for a high sensitive biosensor.

We have carried out a detailed study of gap induced radiation loss effect in a micro-ring resonator. Our data show that small-gap induced loss dominates the total ring loss as the gap is less than 225 nm for TM mode.

A cost-effective process using self-aligned microbonded Ge-beams on silicon waveguides is presented. Heterojunction photodetectors featuring low dark-current of 0.7uA (−2V) and high turn-on current of 10.8 mA (+3V) are demonstrated. The operation bandwidth is 11–16GHz.

We report a silicon avalanche photodetector with low breakdown voltage of −6.44V. Through a design of narrow interdigitated junction spacing and Ni-silicide process, a high avalanche gain of 30 and low dark current are achieved.

In this paper, we demonstrate that micro-particle is able to be transported by two types of integrated photonic devices; one is directional couplers and the other is multimode interferometers. Micro-particles are propelled by the evanescent wave and guided by the interference pattern of optical field inside the devices. By properly designing the device length and operation wavelength, micro-particles can be switched to either one of the output ports connecting the devices.

A silicon-nanocrsytal resonant-cavity light-emitting device is presented. Through microcavity effect, the external-quantum-efficiency increases by 3.5 times and the emission spectra narrows by 1/8. Green, yellow, orange and red colors are emitted by tuning cavity length.

A silicon-based resonant cavity light emitting diode is presented in this paper. Via the microcavity effect, the electroluminescence spectrum is significantly reduced and the emission intensity is enhanced, showing the potential of silicon lighting devices.

We presented polarization-extinguished waveguide couplers for silicon photonic wires. The structure is made by an asymmetric Si waveguide clad by SiC and SiO 2 . A preliminary result shows the polarization-extinction-ratio can be more than 17 dB.

An optical phase modulator for integrated optics was proposed by monolithic integration of deformable silicon photonic wires and MEMS actuators. Via applying voltage, the silicon wire is deformed and the wire length is extended, resulting in change of optical phase. A phase shift of 0.18 π is achieved at a bias of 35 V for a 150 μm wire according to numerical simulation. By cascading many of the MEMS-actuated wires, a π-phase shift can be realized at very low operation voltage. Based on this idea, a MEMS-actuated Mach-Zehnder interferometer was demonstrated.

A highly sensitive biosensor based on a silicon photonic crystal waveguide incorporating microcavities is investigated using two-dimensional Finite Difference Time Domain method. With a microcavity placed near the waveguide, a dip is observed on the waveguide transmission spectrum, corresponding to the resonance wavelength of the cavity. Any change of the medium surrounding to the waveguide and cavity results in the shift of the dip in the transmission spectrum. Our simulation shows an optimal geometry of the cavity nearby the waveguide to have high sensitivity. Several materials with refractive indices ranging from 1 (the air) to 1.57 (Bovine serum albumin - BSA) were studied and showed that the best sensitivity of 194 nm/RIU and limit of detection of 5×10−5 RIU can be achieved. The varied resonance wavelength as a second-order polynomial function of refractive index was observed. The sensor is appropriate for detecting homogeneous medium.

Micro-electro-mechanical systems (MEMS) is a key enabling technology to realize scalable and reconfigurable optical components. Since Peterson (1982) demonstrated the first MEMS scanning mirror, many free-space optical MEMS including digital micromirror devices (DMD), micromirror switches, and optical scanners have been accomplished. In guided-wave optics, MEMS have demonstrated the ability for controlling evanescent and butt coupling between waveguides. This chapter investigates the integration of MEMS actuators with optical microresonators and introduces a new family of tunable photonic devices.

We propose an all-optical 3R regeneration scheme utilizing silicon-wire nonlinear photonics including cross-phase modulation and free-carrier dispersion. From the simulation results, the Q-factor of 10-Gb/s RZ signals can be improved with a suitable free-carrier lifetime.

We review the current state-of-the-art of tunable microdisk/microtoroidal resonators with MEMS-actuated couplers. They are key enabling elements of many wavelength-division-multiplexing switches and tunable filters. The performance of dynamic add-drop and bandwidth-tunable filters will be discussed.

A novel vertically coupled tunable microdisk resonator with integrated MEMS tunable optical couplers is demonstrated. A reconfigurable add-drop filter based on this device shows an extinction ratio of 20 dB