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We demonstrate a high-speed integrated optical link on a silicon chip using low-power silicon microresonator electro-optic modulators and low-capacitance germanium photodetectors. Integrating compact devices to provide multiple functions is essential for building scalable optical interconnects.
The following topics are dealt with: photonic integration technology; photodetectors; optical resonators and photonic crystals; rare earth doped materials; plasmonics and optomechanics; optical sensors and filters; nonlinear silicon photonics; photonic membranes; III-V on silicon devices; optical switching and modulation; and germanium gain and emission.
Ge p-i-n photodiodes integrated with Si variable optical attenuators exhibit low dark current of 60 nA and high responsivity of 0.85 A/W at -1 V. These Ge photodiodes have potential for monolithic integration with other Si photonic components.
We fabricate a silicon microring-based photonic circuit comprising a passive NRZ-to-PRZ signal-format converter and a serial-cascaded modulator for clock-recovery applications. We demonstrate on the same chip 5-Gbit/s format conversion and 5-GHz sampling with 64-ps-width pulses.
We report recent experimental results of two kinds of photodetectors developed in the framework of the European project HELIOS: InAlAs-InGaAs metal-semiconductor-metal photodetectors and germanium photodetectors.
An equivalent circuit model for a separate-absorption-charge-multiplication Ge/Si avalanche photodiode is presented. The current dependence of the resonance frequency scales with square root of current, as expected.
We report high-speed waveguide photodetectors with RPCVD-grown Ge on SOI. The device exhibits a 3 dB bandwidth of ~50 GHz, a responsivity of 0.8 A/W, and a low dark current of 35 nA at lambda ~ 1.55 mum.
We demonstrate high current operation of an evanescently coupled Ge waveguide photodetector grown on top of a Si rib waveguide. A 7.4 mum times 500 mum photodetector was found to dissipate 1.003 W of power (125.49 mA at -8V).
Low dark current of ~10 mA/cm2 by inserting i-Si in as-grown Ge pin photodiodes is dominated by the carrier generation in wider-gap i-Si. This property is useful for photodiode applications of defective Ge prepared at low temperatures.
We demonstrate mesa-type and waveguide-type Ge/Si avalanche photodiodes both with high performances. The gain-bandwidth product was measured as high as 340 GHz and the receiver sensitivity was -28 dBm and -30.4 dBm for mesa-and waveguide-type devices, respectively.
Pedestal-type microdisk resonators with SiN disks and SiO2 slots are fabricated. By selective etching, air-slots for maximum light confinement could be obtained. Resonant modes for both oxide- and air slots were measured using tapered fiber coupling.
Q-factor tuning in stress-engineered microresonators is presented. Bent-edge microdisks (mu-kylix), where highest Q's are 60 nm blue-shifted with respect to flat disks, are used to probe Purcell enhancement of Si-nc emission rate in a wide spectral range.
We report a SOI ring resonator biosensor array with 1 reference ring and 4 sensing rings, using WDM as the addressing scheme. On-chip referencing and temperature shift cancellation are demonstrated, and the differential signal shows a low temperature sensitivity of ~plusmn0.8 pm/degC.
We demonstrate a distortion free tunable delays as long as 72 ps with a 10 GHz bandwidth using thermally tuned silicon microring resonators. The device is compact measuring only 30 mum wide by 250 mum long.
We demonstrate slow light photonic crystal waveguides with low dispersion and propagation loss. We then use this to create a distortion-less 1 byte delay for 25 ps pulses.
We present a simulation approach to estimate the effect of disorder induced backscattering in slow light photonic crystal line-defect waveguides. The backscattering leads to localization and thus limits the maximal length of such waveguides. Loss in passive waveguides in the localization regime reduces ripples in spectral transmission and group delay whereas gain increases these resonant multiple...
We demonstrate a silicon optical switch that can reroute optical signals within a switching time of just 3 ps. The switch is based on photonic crystal waveguides in a directional coupler geometry. The dispersion of the device has been engineered to provide slow-light enhancement, which allows the switching length of the device to be just 5 mum. The 3 ps switching time is demonstrated using free-carriers...
We present a new vertical directional coupler based on the coupling between a polymer waveguide and a photonic crystal waveguide with a very wide stopband.
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