Archimedean spiral cavity ring resonators in silicon as ultra-compact optical comb filters.
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.
Xu
Dan-Xia
DX
Institute for Microstructual Sciences, National Research Council Canada, 1200 Montreal Road, Ottawa, Canada.
Delâge
André
A
McKinnon
Ross
R
Vachon
Martin
M
Ma
Rubin
R
Lapointe
Jean
J
Densmore
Adam
A
Cheben
Pavel
P
Janz
Siegfried
S
Schmid
Jens H
JH