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We present direct bandgap photoluminescence from carrier confinement in Ge/SiGe quantum wells in a microdisk resonator. Based on simulation and experimental results, the Ge/SiGe quantum well structure has great potential to serve as a low pump power Ge laser.
16+ low-noise optical comb lines with 80 GHz spacing and 0 dBm/line output power are generated by a single InAs/GaAs quantum dot (QD) Fabry-Perot laser. Electrical power consumption is reduced dramatically down to 6 mW/line.
We introduce piezo-electric mechanical control and stabilization of frequency combs produced in novel, laser-machined microresonators. The residual and absolute 1-second-stabilities of the 33 GHz comb spacing are 5×10−14 and ≤1.4×10−12, respectively.
We analyze hyper-parametric oscillations in optical microresonators characterized with small group velocity dispersion (GVD) and show that the nonlinear process critically depends on linear interaction among the microresonator modes. The mode interaction changes the local GVD, resulting in either a significant reduction or increase of the oscillation threshold.
We use pulse shaper to investigate frequency combs generation in microresonators in the temporal domain. We observe that different groups of comb lines have different mutual coherence and suggest a model for comb formation.
We evaluate the optical communication performance of individual comb lines generated in silicon nitride microresonators. A high coherence mode yields error-free communications at 10 Gb/s, while a partially coherent mode results in closed eye diagrams.
We report the observation of second harmonic generations from an x-cut beta barium borate (BBO) disk pumped at 1557 nm. This x-cut geometry will provide a new phase matching condition for nonlinear processes in resonators.
The incidence of cancer is predicted to increase dramatically in the next decades. This increase is associated with an aging population - cancer is primarily an age related disease - and with improvements in detection and treatment strategies that cause cancer to be detected earlier and patients to be treated longer.
We show that sharp imaging is possible in microfluidics in flowing turbid media by digital holography. Imaging results are demonstrated for phase objects, i.e. biological cells in microfluidic channels, in flowing liquids with suspended colloidal particles.
Flexible 2D grating with nano-pyramids array used for in-situ and highly sensitive measurement of refractive index and pressure of fluid is demonstrated for potential application in blood monitoring in dialysis.
The laser light reflection intensity on human skin varies depending the ethnicity of each person, in this paper we present an analysis of reflection intensity and how affects the measurement of some optoelectronic devices.
For the last 25 years, microwave photonic (MWP) systems and links have relied almost exclusively on discrete optoelectronic devices, standard optical fibers and fiber-based components. With this concept, various functionalities like RF signal generation, distribution, processing and analysis have been demonstrated. However, configurations with discrete devices are bulky, expensive, high in power consumption...
The development of a novel metamaterial enhanced photonic RF receiver is presented. The receiver consists of a D-ring structure designed on an electro-optic LiNbO3 substrate to achieve direct modulation of RF signal into optical sideband. The optimized D-ring design provides strong electric field confinement, thereby resulting in significant improvement in detection sensitivity. Theoretical modeling,...
Ultra-Fast Uni-Traveling Carrier Photodiodes (UTC-PDs) suitable for active-passive monolithic integration with various Multiple Quantum Well (MQW)-based devices have been designed, fabricated and characterized. The devices achieved a 3-dB bandwidth of up to 170 GHz.
We present the design and characterization of tapped delay line filters fabricated in two-level photonic integrated circuits. Phase error correction techniques are evaluated to enable spectrum analysis of a 4GHz band with 300MHz resolution.
We have designed and fabricated various NFAD devices, and they show reasonable dark count rate and afterpulse probability at 10% PDE. These NFAD devices have great promise to reduce charge flow compared to passively quenched SPADs with hybridly integrated resistance and purely active quenched SPADs, and therefore significantly reduce afterpulse effects. Operating the NFAD is very simple compared to...
We present the performances of new InGaAs/InP Single-Photon Avalanche Diodes (SPADs) for photon counting and timing operation up to about 1700 nm. They have been designed to achieve good detection efficiency, low afterpulsing and very good timing performances. When they are operated at 200 K, with 5 V of excess bias, they show a detection efficiency of more than 25% and a dark count rate of about...
We present our design and characterization on SPADs and NFADs with InGaAs/GaAsSb Type II SL absorber regions on InP substrates with extended wavelength detection up to 2.4µm wavelengths for single photon counting applications. Packaged devices showed very low variation at −40oC, with ∼100nA dark current at 2 volts below breakdown voltage. The measured DCR was 106 Hz at 2 volts excess bias at 223K.
We propose and demonstrate a technique cancel common mode signals of sinusoidally gated single photon avalanche diodes (SPADs). This approach enables the elimination of narrow-band filters that fix the frequency of conventional single photon detection with sine wave gating.
Avalanche photodiodes (APDs) are widely deployed in direct-detection, high-data rate optical-fiber communication systems as well as modern LIDAR systems. Various approaches have been explored to reduce the excess noise of APDs, which is a measure of the uncertainty in the stochastic avalanche gain that the APD offers. They include the use of thin multiplication regions and impact-ionization engineered...
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