Comment on "Nonreciprocal light propagation in a silicon photonic circuit".
We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function.
Ginzton Laboratory, Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA. shanhui@stanford.edu
Shanhui
S
Fan
Roel
R
Baets
Alexander
A
Petrov
Zongfu
Z
Yu
John D
JD
Joannopoulos
Wolfgang
W
Freude
Andrea
A
Melloni
Miloš
M
Popović
Mathias
M
Vanwolleghem
Dirk
D
Jalas
Manfred
M
Eich
Michael
M
Krause
Hagen
H
Renner
Ernst
E
Brinkmeyer
Christopher R
CR
Doerr