Slot waveguides allow joint confinement of the driving electrical radio frequency field and of the optical waveguide mode in a narrow slot, allowing for highly efficient polymer based interferometers. We show that the optical confinement can be simply explained by a perturbation theoretical approach taking into account the continuity of the electric displacement field. We design phase matched transmission lines and show that their impedance and RF losses can be modeled by an equivalent circuit and linked to slot waveguide properties by a simple set of equations, thus allowing optimization of the device without iterative simulations. We optimize the interferometers for analog optical links and predict record performance metrics (V(pi) = 200 mV @ 10 GHz in push-pull configuration) assuming a modest second order nonlinear coefficient (r(33) = 50 pm/V) and slot width (100 nm). Using high performance optical polymers (r(33) = 150 pm/V), noise figures of state of the art analog optical links can be matched while reducing optical power levels by approximately 30 times. With required optical laser power levels predicted at 50 mW, this could be a game changing improvement by bringing high performance optical analog link power requirements in the reach of laser diodes. A modified transmitter architecture allows shot noise limited performance, while reducing power levels in the slot waveguides and enhancing reliability.

An electrically tuned nematic liquid-crystal (LC) infiltrated photonic crystal (PC) laser is demonstrated. This PC laser represents an emerging class of nanoscale optical adaptive devices enabled by the convergence of nonlinear optical materials, electronics, and fluidics that promise increased functionality and utility over existing technologies. A LC cell is constructed by encasing the PC laser between two indium tin oxide glass plates, which serve as the modulating electrodes. Applying a voltage across the cell realigns the LC, modifies the laser cavity's optical path length, and blueshifts the lasing wavelength.

Abstract:We describe a class of modulator design involving slot waveguides and electro-optic polymer claddings. Such geometries enable massive enhancement of index tuning when compared to more conventional geometries. We present a semi-analytic method of predicting the index tuning achievable for a given geometry and electro-optic material. Based on these studies, as well as previous experimental results, we show designs for slot waveguide modulators that, when realized in a Mach-Zehnder configuration, will allow for modulation voltages that are orders of magnitude lower than the state of the art. We also discuss experimental results for nano-slot waveguides. high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor," Nature 427, 615-618 (2004). 13. J. J. Whelehan, "Low-noise amplifiers-then and now," IEEE Trans. on Microwave Theory Techniques 50, 806-813 (2002).

We demonstrate a III-V/silicon hybrid external cavity laser with a tuning range larger than 60 nm at the C-band on a silicon-on-insulator platform. A III-V semiconductor gain chip is hybridized into the silicon chip by edge-coupling the silicon chip through a SiN spot size converter. The demonstrated packaging method requires only passive alignment and is thus suitable for high-volume production. The laser has a largest output power of 11 mW with a maximum wall-plug efficiency of 4.2%, tunability of 60 nm (more than covering the C-band), and a side-mode suppression ratio of 55 dB (>46 dB across the C-band). The lowest measured linewidth is 37 kHz (<80 kHz across the C-band), which is the narrowest linewidth using a silicon-based external cavity. In addition, we successfully demonstrate all silicon-photonics-based transmission of 34 Gbaud (272 Gb/s) dual-polarization 16-QAM using our integrated laser and silicon photonic coherent transceiver. The results show no additional penalty compared to commercially available narrow linewidth tunable lasers. To the best of our knowledge, this is the first experimental demonstration of a complete silicon photonic based coherent link. This is also the first experimental demonstration of >250 Gb/s coherent optical transmission using a silicon micro-ring-based tunable laser.

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We present a compact and low loss 90° optical hybrid on a silicon-on-insulator (SOI) platform for coherent receiving systems. Our 90° optical hybrid uses a novel topology, comprising one Y-junction and three 2x2 multimode interference (MMI) couplers. The geometry of the 90° optical hybrid is fully optimized using particle swarm optimization (PSO). The fabricated 90° optical hybrid has a compact footprint of 21.6 µm x 27.9 µm, with an insertion loss less than 0.5 dB, a common mode rejection ratio (CMRR) larger than 30 dB, and phase error smaller than 3° in the C-band across 22 reticles on one wafer. The measured phase error (< 3°) in a packaged coherent receiver further confirms the excellent performance of the 90° optical hybrid.

An optically triggered liquid crystal infiltrated Q-switched photonic crystal laser is demonstrated. A photonic crystal laser cavity was designed and fabricated to support two orthogonally polarized high-Q cavity modes after liquid crystal infiltration. By controlling the liquid crystal orientation via a layer of photoaddressable polymer and a writing laser, the photonic crystal lasing mode can be reversibly switched between the two modes which also switches the laser's emission polarization and wavelength. The creation of the Q-switched laser demonstrates the benefits of customizing photonic crystal cavities to maximally synergize with an infiltrated material and illustrates the potential of integrating semiconductor nanophotonics with optical materials. ©2005 Optical Society of America References and Links1. E. Yablonovitch, "Inhibited spontaneous emission in solid-state physics and electronics," Phys. Rev. Lett. 58, 2059Lett. 58, -2062Lett. 58, , (1987. 2. S. John, "Strong localization of photons in certain disordered dielectric superlattices," Phys. Rev. Lett. 58, 2486Lett. 58, -2489Lett. 58, , (1987. 3. Y. Akahane, T. Asano, B. Song, and S. Noda, "High-Q photonic nanocavity in a two-dimensional photonic crystal," Nature 425, 944-947, (2003). Phys. Rev. Lett. 83, 967-970, (1999). 12. E. Yablonovitch, "Liquid versus photonic crystals," Nature 401, 539-541, (1999

In order to integrate superdispersive elements based on photonic crystals, such as the superprism, with conventional integrated optics, insertion losses at the interface to the photonic crystal need to be reduced to an acceptable level. We describe a mode matching interface composed of cascaded diffraction gratings that generates the field profile of the photonic crystal Bloch mode from a slab mode. We calculate with threedimensional finite-difference time-domain computation that by interposing such a multilayered grating between an unpatterned slab and a planar photonic crystal, the insertion efficiency is enhanced from 9% to 84%. Each diffraction grating consists of a row of holes and does not require any additional process steps from those used to fabricate the planar photonic crystal. In order to optimize the efficiency of the mode matching interface, constructive interference conditions are imposed between successive gratings and reflections from individual gratings are suppressed. We fabricate devices in silicon on insulator material and show experimental evidence of the Bloch mode structure and of the mode matching mechanism.