CMOS compatible athermal silicon microring resonators

Silicon photonics promises to alleviate the bandwidth bottleneck of modern day computing systems. But silicon photonic devices have the fundamental problem of being highly sensitive to ambient temperature fluctuations due to the high thermo-optic (TO) coefficient of silicon. Most of the approaches proposed to date to overcome this problem either require significant power consumption or incorporate materials which are not CMOS-compatible. Here we demonstrate a new class of optical devices which are passively temperature compensated, based on tailoring the optical mode confinement in silicon waveguides. We demonstrate the operation of a silicon photonic resonator over very wide temperature range of greater than 80 degrees. The fundamental principle behind this work can be extended to other photonic structures such as modulators, routers, switches and filters.Comment: 9 pages, 4 figure

Thermal Control Of Nanophotonic Structures: Towards Low Power Optical Interconnects And Energy Applications

This thesis explores the interplay between temperature and nanophotonics. In the beginning of the thesis, we address the problem of thermal stabilization of silicon photonic devices, which is a major obstacle in low power integration of on-chip optical interconnects. We demonstrate different schemes, at architecture and device levels, to mitigate thermal sensitivity in optical devices. Using one of the schemes, we demonstrate a ring resonator based electro-optic modulator working over 40 degrees. All the athermal schemes are passive and CMOS- compatible, making them more attractive over active feedback based power- hungry techniques. The latter part of the thesis explores photon-based radiative heat transfer processes. Conventional blackbody radiation is much weaker than solid-state phonon based heat transfer, but its spectrum can be tailored easily as opposed to broadband nature of phonons. Near-field thermal radiation provides a way to overcome the traditional blackbody limit by increasing radiative density of states. We use this phenomenon to demonstrate strong near-field cooling of a thermally isolated membrane through evanescent coupling with a tip. Finally we demonstrate thermal rectification by using temperature dependent spectral properties in a radiative channel

Athermal silicon microring electro-optic modulator

We demonstrate a new class of passively temperature stabilized resonant silicon electro-optic modulators. The modulators consist of a ring resonator coupled to a Mach–Zehnder interferometer with tailored thermal properties. We demonstrate 2 GHz continuous modulation over a temperature range of 35 °C and describe the scalability and design rules for such a device. © 2012 Optical Society of America OCIS codes: 130.4110, 120.6780. Silicon microring modulators have been proposed as ubi-quitous workhorse of future on-chip optical networks [1,2]. The resonant nature of these modulators leads to enhancement of small index changes enabling low power and ultracompact devices. However, precisely the same resonant enhancement also leads to high sensitivity to ambient temperature fluctuations. This fundamental lim-itation is due to the large thermo-optic (TO) coefficient of silicon (1.86 × 10−4 K−1) [3]. For example, the resonant wavelength of a ring resonator, made out of a 200 nm