A new low-loss high-index-contrast photonics platform has been developed for integrated optics and microwave photonics. The platform consists of a material system that has an index contrast that is adjustable from 0 to 25% and which is processed using conventional CMOS tools. The platform allows one to four orders of magnitude reduction in the size of optical components compared with conventional planar technologies. As an example, meter long path lengths occupy coils that are millimeters in diameter. Microwave photonic building blocks that are enabled include large bit count programmable delay lines for beam steering and shaping that fit in less than a square centimeter and which have delays controllable from 5 fsec to 10 nsec. Also enabled are arrays of high order tunable filters, a hundred micrometers in size, having linewidths ranging from tens of MHz to tens of GHz. These filters can be tuned over several hundred GHz, and when placed in Vernier architectures can be tuned across the C band (5 THz). An optical chip typically consists of dozens of optical elements. Each element is placed in its own micro-control loop that consists of a thin film heater for thermo-optic control and a thermistor for electronic feedback. The micro-control loops impart intelligence to the optical chip.
We theoretically investigate three approaches to trapping atoms above linear integrated optical waveguides. A two- color scheme balances the decaying evanescent elds of red- and blue-detuned light to produce a potential minimum above the guide. A one-color surface trap proposal uses blue-detuned light and the attractive surface interaction to provide a potential minimum. A third proposal uses blue-detuned light in two guides positioned above and below one another. The atoms are con ned to the \dark" spot in the vacuum gap between the guides. We nd that all three approaches can be used in principle to trap atoms in two- or three-dimensions with a few 10's of mW of laser power. Of these three methods, we show that the dark spot guide is the most robust to power fluctuations and provides the most viable design approach to constructing integrated optical circuits that could transport and manipulate atoms in a controlled manner.
Microring resonators are attractive for Very Large Scale Integrated Photonic Circuits. They have been shown to be capable of many optical signal processing functions, and their small dimensions could lead to integration densities of 10,000 devices per square-cm. Here, the analytic theory of higher order mutually coupled resonators is derived. Experiments involving fabricated ring resonators and resonator arrays is described.
Directional couplers based on antiresonant reflecting optical waveguides (ARROW) have been fabricated and tested. The exchange of power from one waveguide to the other could be well controlled by adjustment of geometrical parameters such as the coupling length and/or the etch depth of the rib ARROW waveguide. Simulations based on the beam propagation method yield good agreement with measurement data and has been found to be indispensable for accurate design and analysis of ARROW directional couplers. Owing to the ARROW structure, the directional couplers presented have the feature that they also perform the polarizing function.
A vector beam propagation method based on finite-difference (FD-VBPM) is developed and described. The polarization property and the hybrid nature of the propagating waves are considered. The assessment and the applications of the FD-VBPM are presented.