Open AccessArchimedean spiral cavity ring resonators in silicon as ultra-compact optical comb filters
Author(s) -
DanXia Xu,
A. Delâge,
Ross McKin,
Martin Vachon,
R. Ma,
J. Lapointe,
A. Densmore,
Pavel Cheben,
Siegfried Janz,
Jens H. Schmid
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.001937
Subject(s) - resonator , optics , extinction ratio , materials science , free spectral range , helical resonator , comb filter , radius , spiral (railway) , insertion loss , coupling coefficient of resonators , filter (signal processing) , optical filter , wavelength , optical cavity , q factor , physics , electrical engineering , mathematical analysis , laser , computer security , mathematics , computer science , engineering
We present an ultra-compact comb filter using an add-drop ring resonator with an Archimedean spiral cavity. The cavity consists of two interleaved spiral branches which are connected in the center using arcs of circle of a radius that causes minimum bend loss. We describe the design procedure and examine the physical parameters governing the resonator performance. As an example, we demonstrate experimentally a comb filter with a 25 GHz channel spacing made of silicon photonic wires and only occupies an area of 80 x 90 microm(2), approximately a 70 fold size reduction compared to a racetrack resonator. The filter transmission is free of spurious reflections, attesting to the smooth transition between different sections of the resonator cavity. Over a 40 channel wavelength span, the filter exhibits a quality factor Q > 35,000, extinction ratios > 10 dB, and an excellent power uniformity with variations < 0.5 dB for both the through and drop ports.