Po Dong

Horizontal single and multiple slot waveguides: optical transmission at λ=1550 nm

We experimentally demonstrate the optical transmission at 1550 nm of the fundamental slot modes (quasi-TM modes) in horizontal single and multiple slot waveguides and ring resonators consisting of deposited amorphous silicon and silicon dioxide. We demonstrate that the horizontal multiple slot configuration provides enhanced optical confinement in low index slot regions compared to a horizontal single slot structure with the same total SiO2 layer thickness by comparing their thermo-optic coefficients for the horizontal slot ring resonators. We show in these early structures that horizontal slot waveguides have low propagation loss of 6~7 dB/cm. The waveguide loss is mainly due to a-Si material absorption. The addition of a-Si/SiO2 interfaces does not introduce significant scattering loss in a horizontal multiple slot waveguide compared to a horizontal single slot waveguide.

All-Optical Comb Switch for Multiwavelength Message Routing in Silicon Photonic Networks

Simultaneous all-optical switching of 20 continuous-wave wavelength channels is achieved in a microring resonator-based silicon broadband 12 comb switch. Moreover, single-channel power penalty measurements are performed during active operation of the switch at both the through and the drop output ports. A statistical characterization of the drop-port insertion losses and extinction ratios of both ports shows broad spectral uniformity, and bit-error-rate measurements during passive operation indicate a negligible increase in signal degradation as the number of wavelength channels exiting the drop port are scaled from one to 16, with peak powers of 6 dBm per channel. A high-speed broadband switching device, such as the one described here, is a crucial element for the deployment of interconnection networks based on silicon photonic integrated circuits.

High performance germanium photodetectors integrated on submicron silicon waveguides by low temperature wafer bonding

We demonstrate germanium photodetectors integrated on submicron silicon waveguides fabricated with a low temperature ( <or=400 degrees C) wafer bonding and ion-cut process. The devices shows a low dark current of approximately 100 nA, a fiber accessed responsivity of > 0.4 A/W and an estimated quantum efficiency of above 90%.

All-optical compact silicon comb switch

We demonstrate a 1x2 all-optical comb switch using a 200 mum diameter silicon ring resonator with a switching time of less than 1 ns. The switch overcomes the small bandwidth of the traditional ring resonator, and works for wavelength division multiplexing applications. The device has a footprint of ~0.04 mm(2) and enables switching of a large number (~40) of wavelength channels spaced by ~0.85 nm.

High-speed all-optical modulation using polycrystalline silicon microring resonators

We experimentally demonstrate on-chip active photonic devices fabricated from deposited polycrystalline silicon, which can be used for monolithic three-dimensional integration of optical networks. The demonstrated modulator is based on all-optical carrier injection in a micrometer-size resonator and has a modulation depth of 10dB and a temporal response of 135ps. Grain boundaries in the polycrystalline silicon (polysilicon) material result in faster electron-hole recombination, enabling a shortened carrier lifetime and a faster optical switching time compared to similar devices based on crystalline silicon.We experimentally demonstrate on-chip active photonic devices fabricated from deposited polycrystalline silicon, which can be used for monolithic three-dimensional integration of optical networks. The demonstrated modulator is based on all-optical carrier injection in a micrometer-size resonator and has a modulation depth of 10dB and a temporal response of 135ps. Grain boundaries in the polycrystalline silicon (polysilicon) material result in faster electron-hole recombination, enabling a shortened carrier lifetime and a faster optical switching time compared to similar devices based on crystalline silicon.

Tunable superluminal propagation on a silicon microchip.

We demonstrate tunable superluminal propagation in a silicon microphotonic device in a solid-state room-temperature device of tens of micrometers in dimension allowing easy integration with high-bandwidth room-temperature systems. We achieve tunable negative delays up to 85 ps and effective group indices tunable between -1158 and -312.

On-chip generation of high-intensity short optical pulses using dynamic microcavities

We experimentally demonstrate generation of high-intensity short optical pulses obtained by the controlled ultrafast release of the stored energy confined in silicon microcavities. This is achieved using ultrafast tuning of the coupling from a coupled-ring cavity to an external waveguide on time scales shorter than cavity photon lifetime.

Silicon Microring Resonator-Based Broadband Comb Switch for Wavelength-Parallel Message Routing

We demonstrate error-free propagation of wavelength-parallel 160-Gb/s optical data in a broadband silicon microring resonator-based comb switch, and observe no power penalty increase associated with inter-channel crosstalk when scaling from one to 16 wavelength channels.

250 Gb/s multi-wavelength operation of microring resonator-based broadband comb switch for silicon photonic networks-on-chip

A 250-Gb/s multi-wavelength signal dynamically routed through a high-speed 1times2 silicon switch advocates low-power networks-on-chip, with power penalties and extinction ratios investigated.

Inducing Photonic Transitions between Discrete Modes in a Microcavity

We demonstrate that transitions between discrete cavity modes in optical microcavities can be induced when the resonance of cavity is tuned on a time scale shorter than the inverse of the frequency difference between modes.