Roberto R. Panepucci

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Photonic circuits, in which beams of light redirect the flow of other beams of light, are a long-standing goal for developing highly integrated optical communication components. Furthermore, it is highly desirable to use silicon--the dominant material in the microelectronic industry--as the platform for such circuits. Photonic structures that bend, split,(More)
We propose and demonstrate an efficient coupler for compact mode conversion between a fiber and a submicrometer waveguide. The coupler is composed of high-index-contrast materials and is based on a short taper with a nanometer-sized tip. We show that the micrometer-long silicon-on-insulator-based nanotaper coupler is able to efficiently convert both the(More)
We experimentally demonstrate a novel silicon waveguide structure for guiding and confining light in nanometer-wide low-refractive-index material. The optical field in the low-index material is enhanced because of the discontinuity of the electric field at high-index-contrast interfaces. We measure a 30% reduction of the effective index of light propagating(More)
We present an experimental demonstration of fast all-optical switching on a silicon photonic integrated device by employing a strong light-confinement structure to enhance sensitivity to small changes in the refractive index. By use of a control light pulse with energy as low as 40 pJ, the optical transmission of the structure is modulated by more than 97%(More)
The hybrid input-output iterative algorithm, which solves the phase problem for scattering from non-periodic objects, is reviewed for application to X-ray and electron diffraction data. Desirable convex constraints, including the sign of the scattering potential for electrons, and compact support, are discussed. The cases of complex and real exit-face(More)
A proof-of-concept for a new and entirely CMOS compatible thermo-optic reconfigurable switch based on a coupled ring resonator structure is experimentally demonstrated in this paper. Preliminary results show that a single optical device is capable of combining several functionalities, such as tunable filtering, non-blocking switching and reconfigurability,(More)
We propose a novel high-index-contrast waveguide structure capable of light strong confinement and guiding in low-refractive-index materials. The principle of operation of this structure relies on the electric field (E-field) discontinuity at the interface between high-indexcontrast materials. We show that by using such a structure the E-field can be(More)
Tunable silicon microring filters are used to demonstrate CMOS-compatible on-chip wavelength control of Er(+) doped fiber-lasers. An onchip Ni-Cr micro-heater consuming up to 20 mW is capable of tuning the Si microring filter by 1.3 nm with a lasing linewidths narrower than 0.02 nm. This approach enables arbitrary multiple wavelength generation on a silicon(More)
A set of low noise transimpedance amplifiers fabricated and characterized in CMOS and BiCMOS technologies are proposed in this work. Layout optimization, efficient modeling and bias point optimization are the techniques employed to reduce the input noise current density. The CMOS amplifiers were designed to work at 10 Gbps. The BiCMOS amplifiers, based on(More)
Design guide lines are given for developing SiGe HBT mm-wave d.c. coupled ultra-wide-band low noise monolithic amplifiers. An ultra wide band LNA and two mm-wave TIAs for 40 Gbps and 100 Gbps applications are proposed. The LNA has S21=11 dB and a 3-dB bandwidth of 88 GHz. The 40 Gbps TIA has a new topology, allowing a DC coupled performance, 54 dBΩ(More)